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rocksdb/util/file_reader_writer.cc

1086 lines
36 KiB

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "util/file_reader_writer.h"
#include <algorithm>
#include <mutex>
#include "monitoring/histogram.h"
#include "monitoring/iostats_context_imp.h"
#include "port/port.h"
#include "test_util/sync_point.h"
#include "util/random.h"
#include "util/rate_limiter.h"
namespace rocksdb {
#ifndef NDEBUG
namespace {
bool IsFileSectorAligned(const size_t off, size_t sector_size) {
return off % sector_size == 0;
}
}
#endif
Status SequentialFileReader::Read(size_t n, Slice* result, char* scratch) {
Status s;
if (use_direct_io()) {
#ifndef ROCKSDB_LITE
size_t offset = offset_.fetch_add(n);
size_t alignment = file_->GetRequiredBufferAlignment();
size_t aligned_offset = TruncateToPageBoundary(alignment, offset);
size_t offset_advance = offset - aligned_offset;
size_t size = Roundup(offset + n, alignment) - aligned_offset;
size_t r = 0;
AlignedBuffer buf;
buf.Alignment(alignment);
buf.AllocateNewBuffer(size);
Slice tmp;
s = file_->PositionedRead(aligned_offset, size, &tmp, buf.BufferStart());
if (s.ok() && offset_advance < tmp.size()) {
buf.Size(tmp.size());
r = buf.Read(scratch, offset_advance,
std::min(tmp.size() - offset_advance, n));
}
*result = Slice(scratch, r);
#endif // !ROCKSDB_LITE
} else {
s = file_->Read(n, result, scratch);
}
IOSTATS_ADD(bytes_read, result->size());
return s;
}
Status SequentialFileReader::Skip(uint64_t n) {
#ifndef ROCKSDB_LITE
if (use_direct_io()) {
offset_ += static_cast<size_t>(n);
return Status::OK();
}
#endif // !ROCKSDB_LITE
return file_->Skip(n);
}
Status RandomAccessFileReader::Read(uint64_t offset, size_t n, Slice* result,
char* scratch, bool for_compaction) const {
Status s;
uint64_t elapsed = 0;
{
StopWatch sw(env_, stats_, hist_type_,
(stats_ != nullptr) ? &elapsed : nullptr, true /*overwrite*/,
true /*delay_enabled*/);
auto prev_perf_level = GetPerfLevel();
IOSTATS_TIMER_GUARD(read_nanos);
if (use_direct_io()) {
#ifndef ROCKSDB_LITE
size_t alignment = file_->GetRequiredBufferAlignment();
size_t aligned_offset = TruncateToPageBoundary(alignment, static_cast<size_t>(offset));
size_t offset_advance = static_cast<size_t>(offset) - aligned_offset;
size_t read_size = Roundup(static_cast<size_t>(offset + n), alignment) - aligned_offset;
AlignedBuffer buf;
buf.Alignment(alignment);
buf.AllocateNewBuffer(read_size);
while (buf.CurrentSize() < read_size) {
size_t allowed;
if (for_compaction && rate_limiter_ != nullptr) {
allowed = rate_limiter_->RequestToken(
buf.Capacity() - buf.CurrentSize(), buf.Alignment(),
Env::IOPriority::IO_LOW, stats_, RateLimiter::OpType::kRead);
} else {
assert(buf.CurrentSize() == 0);
allowed = read_size;
}
Slice tmp;
FileOperationInfo::TimePoint start_ts;
uint64_t orig_offset = 0;
if (ShouldNotifyListeners()) {
start_ts = std::chrono::system_clock::now();
orig_offset = aligned_offset + buf.CurrentSize();
}
{
IOSTATS_CPU_TIMER_GUARD(cpu_read_nanos, env_);
s = file_->Read(aligned_offset + buf.CurrentSize(), allowed, &tmp,
buf.Destination());
}
if (ShouldNotifyListeners()) {
auto finish_ts = std::chrono::system_clock::now();
NotifyOnFileReadFinish(orig_offset, tmp.size(), start_ts, finish_ts,
s);
}
buf.Size(buf.CurrentSize() + tmp.size());
if (!s.ok() || tmp.size() < allowed) {
break;
}
}
size_t res_len = 0;
if (s.ok() && offset_advance < buf.CurrentSize()) {
res_len = buf.Read(scratch, offset_advance,
std::min(buf.CurrentSize() - offset_advance, n));
}
*result = Slice(scratch, res_len);
#endif // !ROCKSDB_LITE
} else {
size_t pos = 0;
const char* res_scratch = nullptr;
while (pos < n) {
size_t allowed;
if (for_compaction && rate_limiter_ != nullptr) {
if (rate_limiter_->IsRateLimited(RateLimiter::OpType::kRead)) {
sw.DelayStart();
}
allowed = rate_limiter_->RequestToken(n - pos, 0 /* alignment */,
Env::IOPriority::IO_LOW, stats_,
RateLimiter::OpType::kRead);
if (rate_limiter_->IsRateLimited(RateLimiter::OpType::kRead)) {
sw.DelayStop();
}
} else {
allowed = n;
}
Slice tmp_result;
#ifndef ROCKSDB_LITE
FileOperationInfo::TimePoint start_ts;
if (ShouldNotifyListeners()) {
start_ts = std::chrono::system_clock::now();
}
#endif
{
IOSTATS_CPU_TIMER_GUARD(cpu_read_nanos, env_);
s = file_->Read(offset + pos, allowed, &tmp_result, scratch + pos);
}
#ifndef ROCKSDB_LITE
if (ShouldNotifyListeners()) {
auto finish_ts = std::chrono::system_clock::now();
NotifyOnFileReadFinish(offset + pos, tmp_result.size(), start_ts,
finish_ts, s);
}
#endif
if (res_scratch == nullptr) {
// we can't simply use `scratch` because reads of mmap'd files return
// data in a different buffer.
res_scratch = tmp_result.data();
} else {
// make sure chunks are inserted contiguously into `res_scratch`.
assert(tmp_result.data() == res_scratch + pos);
}
pos += tmp_result.size();
if (!s.ok() || tmp_result.size() < allowed) {
break;
}
}
*result = Slice(res_scratch, s.ok() ? pos : 0);
}
IOSTATS_ADD_IF_POSITIVE(bytes_read, result->size());
SetPerfLevel(prev_perf_level);
}
if (stats_ != nullptr && file_read_hist_ != nullptr) {
file_read_hist_->Add(elapsed);
}
return s;
}
Status RandomAccessFileReader::MultiRead(ReadRequest* read_reqs,
size_t num_reqs) const {
Status s;
uint64_t elapsed = 0;
assert(!use_direct_io());
{
StopWatch sw(env_, stats_, hist_type_,
(stats_ != nullptr) ? &elapsed : nullptr, true /*overwrite*/,
true /*delay_enabled*/);
auto prev_perf_level = GetPerfLevel();
IOSTATS_TIMER_GUARD(read_nanos);
#ifndef ROCKSDB_LITE
FileOperationInfo::TimePoint start_ts;
if (ShouldNotifyListeners()) {
start_ts = std::chrono::system_clock::now();
}
#endif // ROCKSDB_LITE
{
IOSTATS_CPU_TIMER_GUARD(cpu_read_nanos, env_);
s = file_->MultiRead(read_reqs, num_reqs);
}
for (size_t i = 0; i < num_reqs; ++i) {
#ifndef ROCKSDB_LITE
if (ShouldNotifyListeners()) {
auto finish_ts = std::chrono::system_clock::now();
NotifyOnFileReadFinish(read_reqs[i].offset,
read_reqs[i].result.size(), start_ts, finish_ts,
read_reqs[i].status);
}
#endif // ROCKSDB_LITE
IOSTATS_ADD_IF_POSITIVE(bytes_read, read_reqs[i].result.size());
}
SetPerfLevel(prev_perf_level);
}
if (stats_ != nullptr && file_read_hist_ != nullptr) {
file_read_hist_->Add(elapsed);
}
return s;
}
Status WritableFileWriter::Append(const Slice& data) {
const char* src = data.data();
size_t left = data.size();
Status s;
pending_sync_ = true;
TEST_KILL_RANDOM("WritableFileWriter::Append:0",
rocksdb_kill_odds * REDUCE_ODDS2);
{
IOSTATS_TIMER_GUARD(prepare_write_nanos);
TEST_SYNC_POINT("WritableFileWriter::Append:BeforePrepareWrite");
writable_file_->PrepareWrite(static_cast<size_t>(GetFileSize()), left);
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
// See whether we need to enlarge the buffer to avoid the flush
if (buf_.Capacity() - buf_.CurrentSize() < left) {
for (size_t cap = buf_.Capacity();
cap < max_buffer_size_; // There is still room to increase
cap *= 2) {
// See whether the next available size is large enough.
// Buffer will never be increased to more than max_buffer_size_.
size_t desired_capacity = std::min(cap * 2, max_buffer_size_);
if (desired_capacity - buf_.CurrentSize() >= left ||
(use_direct_io() && desired_capacity == max_buffer_size_)) {
buf_.AllocateNewBuffer(desired_capacity, true);
break;
}
}
}
// Flush only when buffered I/O
if (!use_direct_io() && (buf_.Capacity() - buf_.CurrentSize()) < left) {
if (buf_.CurrentSize() > 0) {
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
s = Flush();
if (!s.ok()) {
return s;
}
}
assert(buf_.CurrentSize() == 0);
}
// We never write directly to disk with direct I/O on.
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
// or we simply use it for its original purpose to accumulate many small
// chunks
if (use_direct_io() || (buf_.Capacity() >= left)) {
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
while (left > 0) {
size_t appended = buf_.Append(src, left);
left -= appended;
src += appended;
if (left > 0) {
s = Flush();
if (!s.ok()) {
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
break;
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
}
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
} else {
// Writing directly to file bypassing the buffer
assert(buf_.CurrentSize() == 0);
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
s = WriteBuffered(src, left);
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
TEST_KILL_RANDOM("WritableFileWriter::Append:1", rocksdb_kill_odds);
if (s.ok()) {
filesize_ += data.size();
}
return s;
}
Status WritableFileWriter::Pad(const size_t pad_bytes) {
assert(pad_bytes < kDefaultPageSize);
size_t left = pad_bytes;
size_t cap = buf_.Capacity() - buf_.CurrentSize();
// Assume pad_bytes is small compared to buf_ capacity. So we always
// use buf_ rather than write directly to file in certain cases like
// Append() does.
while (left) {
size_t append_bytes = std::min(cap, left);
buf_.PadWith(append_bytes, 0);
left -= append_bytes;
if (left > 0) {
Status s = Flush();
if (!s.ok()) {
return s;
}
}
cap = buf_.Capacity() - buf_.CurrentSize();
}
pending_sync_ = true;
filesize_ += pad_bytes;
return Status::OK();
}
Status WritableFileWriter::Close() {
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
// Do not quit immediately on failure the file MUST be closed
Status s;
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
// Possible to close it twice now as we MUST close
// in __dtor, simply flushing is not enough
// Windows when pre-allocating does not fill with zeros
// also with unbuffered access we also set the end of data.
if (!writable_file_) {
return s;
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
s = Flush(); // flush cache to OS
Status interim;
// In direct I/O mode we write whole pages so
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
// we need to let the file know where data ends.
if (use_direct_io()) {
interim = writable_file_->Truncate(filesize_);
if (interim.ok()) {
interim = writable_file_->Fsync();
}
if (!interim.ok() && s.ok()) {
s = interim;
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
}
TEST_KILL_RANDOM("WritableFileWriter::Close:0", rocksdb_kill_odds);
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
interim = writable_file_->Close();
if (!interim.ok() && s.ok()) {
s = interim;
}
writable_file_.reset();
TEST_KILL_RANDOM("WritableFileWriter::Close:1", rocksdb_kill_odds);
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
return s;
}
// write out the cached data to the OS cache or storage if direct I/O
// enabled
Status WritableFileWriter::Flush() {
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
Status s;
TEST_KILL_RANDOM("WritableFileWriter::Flush:0",
rocksdb_kill_odds * REDUCE_ODDS2);
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
if (buf_.CurrentSize() > 0) {
if (use_direct_io()) {
#ifndef ROCKSDB_LITE
if (pending_sync_) {
s = WriteDirect();
}
#endif // !ROCKSDB_LITE
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
} else {
s = WriteBuffered(buf_.BufferStart(), buf_.CurrentSize());
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
}
if (!s.ok()) {
return s;
}
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
s = writable_file_->Flush();
if (!s.ok()) {
return s;
}
// sync OS cache to disk for every bytes_per_sync_
// TODO: give log file and sst file different options (log
// files could be potentially cached in OS for their whole
// life time, thus we might not want to flush at all).
// We try to avoid sync to the last 1MB of data. For two reasons:
// (1) avoid rewrite the same page that is modified later.
// (2) for older version of OS, write can block while writing out
// the page.
// Xfs does neighbor page flushing outside of the specified ranges. We
// need to make sure sync range is far from the write offset.
if (!use_direct_io() && bytes_per_sync_) {
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
const uint64_t kBytesNotSyncRange = 1024 * 1024; // recent 1MB is not synced.
const uint64_t kBytesAlignWhenSync = 4 * 1024; // Align 4KB.
if (filesize_ > kBytesNotSyncRange) {
uint64_t offset_sync_to = filesize_ - kBytesNotSyncRange;
offset_sync_to -= offset_sync_to % kBytesAlignWhenSync;
assert(offset_sync_to >= last_sync_size_);
if (offset_sync_to > 0 &&
offset_sync_to - last_sync_size_ >= bytes_per_sync_) {
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
s = RangeSync(last_sync_size_, offset_sync_to - last_sync_size_);
last_sync_size_ = offset_sync_to;
}
}
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
return s;
}
Status WritableFileWriter::Sync(bool use_fsync) {
Status s = Flush();
if (!s.ok()) {
return s;
}
TEST_KILL_RANDOM("WritableFileWriter::Sync:0", rocksdb_kill_odds);
if (!use_direct_io() && pending_sync_) {
s = SyncInternal(use_fsync);
if (!s.ok()) {
return s;
}
}
TEST_KILL_RANDOM("WritableFileWriter::Sync:1", rocksdb_kill_odds);
pending_sync_ = false;
return Status::OK();
}
Status WritableFileWriter::SyncWithoutFlush(bool use_fsync) {
if (!writable_file_->IsSyncThreadSafe()) {
return Status::NotSupported(
"Can't WritableFileWriter::SyncWithoutFlush() because "
"WritableFile::IsSyncThreadSafe() is false");
}
TEST_SYNC_POINT("WritableFileWriter::SyncWithoutFlush:1");
Status s = SyncInternal(use_fsync);
TEST_SYNC_POINT("WritableFileWriter::SyncWithoutFlush:2");
return s;
}
Status WritableFileWriter::SyncInternal(bool use_fsync) {
Status s;
IOSTATS_TIMER_GUARD(fsync_nanos);
TEST_SYNC_POINT("WritableFileWriter::SyncInternal:0");
auto prev_perf_level = GetPerfLevel();
IOSTATS_CPU_TIMER_GUARD(cpu_write_nanos, env_);
if (use_fsync) {
s = writable_file_->Fsync();
} else {
s = writable_file_->Sync();
}
SetPerfLevel(prev_perf_level);
return s;
}
Status WritableFileWriter::RangeSync(uint64_t offset, uint64_t nbytes) {
IOSTATS_TIMER_GUARD(range_sync_nanos);
TEST_SYNC_POINT("WritableFileWriter::RangeSync:0");
return writable_file_->RangeSync(offset, nbytes);
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
// This method writes to disk the specified data and makes use of the rate
// limiter if available
Status WritableFileWriter::WriteBuffered(const char* data, size_t size) {
Status s;
assert(!use_direct_io());
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
const char* src = data;
size_t left = size;
while (left > 0) {
size_t allowed;
if (rate_limiter_ != nullptr) {
allowed = rate_limiter_->RequestToken(
left, 0 /* alignment */, writable_file_->GetIOPriority(), stats_,
RateLimiter::OpType::kWrite);
} else {
allowed = left;
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
{
IOSTATS_TIMER_GUARD(write_nanos);
TEST_SYNC_POINT("WritableFileWriter::Flush:BeforeAppend");
#ifndef ROCKSDB_LITE
FileOperationInfo::TimePoint start_ts;
uint64_t old_size = writable_file_->GetFileSize();
if (ShouldNotifyListeners()) {
start_ts = std::chrono::system_clock::now();
old_size = next_write_offset_;
}
#endif
{
auto prev_perf_level = GetPerfLevel();
IOSTATS_CPU_TIMER_GUARD(cpu_write_nanos, env_);
s = writable_file_->Append(Slice(src, allowed));
SetPerfLevel(prev_perf_level);
}
#ifndef ROCKSDB_LITE
if (ShouldNotifyListeners()) {
auto finish_ts = std::chrono::system_clock::now();
NotifyOnFileWriteFinish(old_size, allowed, start_ts, finish_ts, s);
}
#endif
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
if (!s.ok()) {
return s;
}
}
IOSTATS_ADD(bytes_written, allowed);
TEST_KILL_RANDOM("WritableFileWriter::WriteBuffered:0", rocksdb_kill_odds);
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
left -= allowed;
src += allowed;
}
buf_.Size(0);
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
return s;
}
// This flushes the accumulated data in the buffer. We pad data with zeros if
// necessary to the whole page.
// However, during automatic flushes padding would not be necessary.
// We always use RateLimiter if available. We move (Refit) any buffer bytes
// that are left over the
// whole number of pages to be written again on the next flush because we can
// only write on aligned
// offsets.
#ifndef ROCKSDB_LITE
Status WritableFileWriter::WriteDirect() {
assert(use_direct_io());
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
Status s;
const size_t alignment = buf_.Alignment();
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
assert((next_write_offset_ % alignment) == 0);
// Calculate whole page final file advance if all writes succeed
size_t file_advance =
TruncateToPageBoundary(alignment, buf_.CurrentSize());
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
// Calculate the leftover tail, we write it here padded with zeros BUT we
// will write
// it again in the future either on Close() OR when the current whole page
// fills out
size_t leftover_tail = buf_.CurrentSize() - file_advance;
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
// Round up and pad
buf_.PadToAlignmentWith(0);
const char* src = buf_.BufferStart();
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
uint64_t write_offset = next_write_offset_;
size_t left = buf_.CurrentSize();
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
while (left > 0) {
// Check how much is allowed
size_t size;
if (rate_limiter_ != nullptr) {
size = rate_limiter_->RequestToken(left, buf_.Alignment(),
writable_file_->GetIOPriority(),
stats_, RateLimiter::OpType::kWrite);
} else {
size = left;
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
{
IOSTATS_TIMER_GUARD(write_nanos);
TEST_SYNC_POINT("WritableFileWriter::Flush:BeforeAppend");
FileOperationInfo::TimePoint start_ts;
if (ShouldNotifyListeners()) {
start_ts = std::chrono::system_clock::now();
}
// direct writes must be positional
s = writable_file_->PositionedAppend(Slice(src, size), write_offset);
if (ShouldNotifyListeners()) {
auto finish_ts = std::chrono::system_clock::now();
NotifyOnFileWriteFinish(write_offset, size, start_ts, finish_ts, s);
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
if (!s.ok()) {
buf_.Size(file_advance + leftover_tail);
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
return s;
}
}
IOSTATS_ADD(bytes_written, size);
left -= size;
src += size;
write_offset += size;
assert((next_write_offset_ % alignment) == 0);
}
if (s.ok()) {
// Move the tail to the beginning of the buffer
// This never happens during normal Append but rather during
// explicit call to Flush()/Sync() or Close()
buf_.RefitTail(file_advance, leftover_tail);
// This is where we start writing next time which may or not be
// the actual file size on disk. They match if the buffer size
// is a multiple of whole pages otherwise filesize_ is leftover_tail
// behind
next_write_offset_ += file_advance;
}
return s;
}
#endif // !ROCKSDB_LITE
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
namespace {
class ReadaheadRandomAccessFile : public RandomAccessFile {
public:
ReadaheadRandomAccessFile(std::unique_ptr<RandomAccessFile>&& file,
size_t readahead_size)
: file_(std::move(file)),
alignment_(file_->GetRequiredBufferAlignment()),
readahead_size_(Roundup(readahead_size, alignment_)),
buffer_(),
buffer_offset_(0) {
buffer_.Alignment(alignment_);
buffer_.AllocateNewBuffer(readahead_size_);
}
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
ReadaheadRandomAccessFile(const ReadaheadRandomAccessFile&) = delete;
ReadaheadRandomAccessFile& operator=(const ReadaheadRandomAccessFile&) = delete;
Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const override {
// Read-ahead only make sense if we have some slack left after reading
if (n + alignment_ >= readahead_size_) {
return file_->Read(offset, n, result, scratch);
}
std::unique_lock<std::mutex> lk(lock_);
size_t cached_len = 0;
// Check if there is a cache hit, meaning that [offset, offset + n) is either
// completely or partially in the buffer.
// If it's completely cached, including end of file case when offset + n is
// greater than EOF, then return.
if (TryReadFromCache(offset, n, &cached_len, scratch) &&
(cached_len == n || buffer_.CurrentSize() < readahead_size_)) {
// We read exactly what we needed, or we hit end of file - return.
*result = Slice(scratch, cached_len);
return Status::OK();
}
size_t advanced_offset = static_cast<size_t>(offset + cached_len);
// In the case of cache hit advanced_offset is already aligned, means that
// chunk_offset equals to advanced_offset
size_t chunk_offset = TruncateToPageBoundary(alignment_, advanced_offset);
Status s = ReadIntoBuffer(chunk_offset, readahead_size_);
if (s.ok()) {
// The data we need is now in cache, so we can safely read it
size_t remaining_len;
TryReadFromCache(advanced_offset, n - cached_len, &remaining_len,
scratch + cached_len);
*result = Slice(scratch, cached_len + remaining_len);
}
return s;
}
Status Prefetch(uint64_t offset, size_t n) override {
if (n < readahead_size_) {
// Don't allow smaller prefetches than the configured `readahead_size_`.
// `Read()` assumes a smaller prefetch buffer indicates EOF was reached.
return Status::OK();
}
std::unique_lock<std::mutex> lk(lock_);
size_t offset_ = static_cast<size_t>(offset);
size_t prefetch_offset = TruncateToPageBoundary(alignment_, offset_);
if (prefetch_offset == buffer_offset_) {
return Status::OK();
}
return ReadIntoBuffer(prefetch_offset,
Roundup(offset_ + n, alignment_) - prefetch_offset);
}
size_t GetUniqueId(char* id, size_t max_size) const override {
return file_->GetUniqueId(id, max_size);
}
void Hint(AccessPattern pattern) override { file_->Hint(pattern); }
Status InvalidateCache(size_t offset, size_t length) override {
std::unique_lock<std::mutex> lk(lock_);
buffer_.Clear();
return file_->InvalidateCache(offset, length);
}
bool use_direct_io() const override { return file_->use_direct_io(); }
private:
// Tries to read from buffer_ n bytes starting at offset. If anything was read
// from the cache, it sets cached_len to the number of bytes actually read,
// copies these number of bytes to scratch and returns true.
// If nothing was read sets cached_len to 0 and returns false.
bool TryReadFromCache(uint64_t offset, size_t n, size_t* cached_len,
char* scratch) const {
if (offset < buffer_offset_ ||
offset >= buffer_offset_ + buffer_.CurrentSize()) {
*cached_len = 0;
return false;
}
uint64_t offset_in_buffer = offset - buffer_offset_;
*cached_len = std::min(
buffer_.CurrentSize() - static_cast<size_t>(offset_in_buffer), n);
memcpy(scratch, buffer_.BufferStart() + offset_in_buffer, *cached_len);
return true;
}
// Reads into buffer_ the next n bytes from file_ starting at offset.
// Can actually read less if EOF was reached.
// Returns the status of the read operastion on the file.
Status ReadIntoBuffer(uint64_t offset, size_t n) const {
if (n > buffer_.Capacity()) {
n = buffer_.Capacity();
}
assert(IsFileSectorAligned(offset, alignment_));
assert(IsFileSectorAligned(n, alignment_));
Slice result;
Status s = file_->Read(offset, n, &result, buffer_.BufferStart());
if (s.ok()) {
buffer_offset_ = offset;
buffer_.Size(result.size());
assert(result.size() == 0 || buffer_.BufferStart() == result.data());
}
return s;
}
const std::unique_ptr<RandomAccessFile> file_;
const size_t alignment_;
const size_t readahead_size_;
mutable std::mutex lock_;
// The buffer storing the prefetched data
mutable AlignedBuffer buffer_;
// The offset in file_, corresponding to data stored in buffer_
mutable uint64_t buffer_offset_;
};
// This class wraps a SequentialFile, exposing same API, with the differenece
// of being able to prefetch up to readahead_size bytes and then serve them
// from memory, avoiding the entire round-trip if, for example, the data for the
// file is actually remote.
class ReadaheadSequentialFile : public SequentialFile {
public:
ReadaheadSequentialFile(std::unique_ptr<SequentialFile>&& file,
size_t readahead_size)
: file_(std::move(file)),
alignment_(file_->GetRequiredBufferAlignment()),
readahead_size_(Roundup(readahead_size, alignment_)),
buffer_(),
buffer_offset_(0),
read_offset_(0) {
buffer_.Alignment(alignment_);
buffer_.AllocateNewBuffer(readahead_size_);
}
ReadaheadSequentialFile(const ReadaheadSequentialFile&) = delete;
ReadaheadSequentialFile& operator=(const ReadaheadSequentialFile&) = delete;
Status Read(size_t n, Slice* result, char* scratch) override {
std::unique_lock<std::mutex> lk(lock_);
size_t cached_len = 0;
// Check if there is a cache hit, meaning that [offset, offset + n) is
// either completely or partially in the buffer. If it's completely cached,
// including end of file case when offset + n is greater than EOF, then
// return.
if (TryReadFromCache(n, &cached_len, scratch) &&
(cached_len == n || buffer_.CurrentSize() < readahead_size_)) {
// We read exactly what we needed, or we hit end of file - return.
*result = Slice(scratch, cached_len);
return Status::OK();
}
n -= cached_len;
Status s;
// Read-ahead only make sense if we have some slack left after reading
if (n + alignment_ >= readahead_size_) {
s = file_->Read(n, result, scratch + cached_len);
if (s.ok()) {
read_offset_ += result->size();
*result = Slice(scratch, cached_len + result->size());
}
buffer_.Clear();
return s;
}
s = ReadIntoBuffer(readahead_size_);
if (s.ok()) {
// The data we need is now in cache, so we can safely read it
size_t remaining_len;
TryReadFromCache(n, &remaining_len, scratch + cached_len);
*result = Slice(scratch, cached_len + remaining_len);
}
return s;
}
Status Skip(uint64_t n) override {
std::unique_lock<std::mutex> lk(lock_);
Status s = Status::OK();
// First check if we need to skip already cached data
if (buffer_.CurrentSize() > 0) {
// Do we need to skip beyond cached data?
if (read_offset_ + n >= buffer_offset_ + buffer_.CurrentSize()) {
// Yes. Skip whaterver is in memory and adjust offset accordingly
n -= buffer_offset_ + buffer_.CurrentSize() - read_offset_;
read_offset_ = buffer_offset_ + buffer_.CurrentSize();
} else {
// No. The entire section to be skipped is entirely i cache.
read_offset_ += n;
n = 0;
}
}
if (n > 0) {
// We still need to skip more, so call the file API for skipping
s = file_->Skip(n);
if (s.ok()) {
read_offset_ += n;
}
buffer_.Clear();
}
return s;
}
Status PositionedRead(uint64_t offset, size_t n, Slice* result,
char* scratch) override {
return file_->PositionedRead(offset, n, result, scratch);
}
Status InvalidateCache(size_t offset, size_t length) override {
std::unique_lock<std::mutex> lk(lock_);
buffer_.Clear();
return file_->InvalidateCache(offset, length);
}
bool use_direct_io() const override { return file_->use_direct_io(); }
private:
// Tries to read from buffer_ n bytes. If anything was read from the cache, it
// sets cached_len to the number of bytes actually read, copies these number
// of bytes to scratch and returns true.
// If nothing was read sets cached_len to 0 and returns false.
bool TryReadFromCache(size_t n, size_t* cached_len, char* scratch) {
if (read_offset_ < buffer_offset_ ||
read_offset_ >= buffer_offset_ + buffer_.CurrentSize()) {
*cached_len = 0;
return false;
}
uint64_t offset_in_buffer = read_offset_ - buffer_offset_;
*cached_len = std::min(
buffer_.CurrentSize() - static_cast<size_t>(offset_in_buffer), n);
memcpy(scratch, buffer_.BufferStart() + offset_in_buffer, *cached_len);
read_offset_ += *cached_len;
return true;
}
// Reads into buffer_ the next n bytes from file_.
// Can actually read less if EOF was reached.
// Returns the status of the read operastion on the file.
Status ReadIntoBuffer(size_t n) {
if (n > buffer_.Capacity()) {
n = buffer_.Capacity();
}
assert(IsFileSectorAligned(n, alignment_));
Slice result;
Status s = file_->Read(n, &result, buffer_.BufferStart());
if (s.ok()) {
buffer_offset_ = read_offset_;
buffer_.Size(result.size());
assert(result.size() == 0 || buffer_.BufferStart() == result.data());
}
return s;
}
const std::unique_ptr<SequentialFile> file_;
const size_t alignment_;
const size_t readahead_size_;
std::mutex lock_;
// The buffer storing the prefetched data
AlignedBuffer buffer_;
// The offset in file_, corresponding to data stored in buffer_
uint64_t buffer_offset_;
// The offset up to which data was read from file_. In fact, it can be larger
// than the actual file size, since the file_->Skip(n) call doesn't return the
// actual number of bytes that were skipped, which can be less than n.
// This is not a problemm since read_offset_ is monotonically increasing and
// its only use is to figure out if next piece of data should be read from
// buffer_ or file_ directly.
uint64_t read_offset_;
};
} // namespace
Status FilePrefetchBuffer::Prefetch(RandomAccessFileReader* reader,
uint64_t offset, size_t n,
bool for_compaction) {
size_t alignment = reader->file()->GetRequiredBufferAlignment();
size_t offset_ = static_cast<size_t>(offset);
uint64_t rounddown_offset = Rounddown(offset_, alignment);
uint64_t roundup_end = Roundup(offset_ + n, alignment);
uint64_t roundup_len = roundup_end - rounddown_offset;
assert(roundup_len >= alignment);
assert(roundup_len % alignment == 0);
Improve direct IO range scan performance with readahead (#3884) Summary: This PR extends the improvements in #3282 to also work when using Direct IO. We see **4.5X performance improvement** in seekrandom benchmark doing long range scans, when using direct reads, on flash. **Description:** This change improves the performance of iterators doing long range scans (e.g. big/full index or table scans in MyRocks) by using readahead and prefetching additional data on each disk IO, and storing in a local buffer. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan. **Implementation Details:** - Used `FilePrefetchBuffer` as the underlying buffer to store the readahead data. `FilePrefetchBuffer` can now take file_reader, readahead_size and max_readahead_size as input to the constructor, and automatically do readahead. - `FilePrefetchBuffer::TryReadFromCache` can now call `FilePrefetchBuffer::Prefetch` if readahead is enabled. - `AlignedBuffer` (which is the underlying store for `FilePrefetchBuffer`) now takes a few additional args in `AlignedBuffer::AllocateNewBuffer` to allow copying data from the old buffer. - Made sure not to re-read partial chunks of data that were already available in the buffer, from device again. - Fixed a couple of cases where `AlignedBuffer::cursize_` was not being properly kept up-to-date. **Constraints:** - Similar to #3282, this gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value). - Since the prefetched data is stored in a temporary buffer allocated on heap, this could increase the memory usage if you have many iterators doing long range scans simultaneously. - Enabled only for user reads, and disabled for compactions. Compaction reads are controlled by the options `use_direct_io_for_flush_and_compaction` and `compaction_readahead_size`, and the current feature takes precautions not to mess with them. **Benchmarks:** I used the same benchmark as used in #3282. Data fill: ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes ``` Do a long range scan: Seekrandom with large number of nexts ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -use_direct_reads -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram ``` ``` Before: seekrandom : 37939.906 micros/op 26 ops/sec; 29.2 MB/s (1636 of 1999 found) With this change: seekrandom : 8527.720 micros/op 117 ops/sec; 129.7 MB/s (6530 of 7999 found) ``` ~4.5X perf improvement. Taken on an average of 3 runs. Closes https://github.com/facebook/rocksdb/pull/3884 Differential Revision: D8082143 Pulled By: sagar0 fbshipit-source-id: 4d7a8561cbac03478663713df4d31ad2620253bb
6 years ago
// Check if requested bytes are in the existing buffer_.
// If all bytes exist -- return.
// If only a few bytes exist -- reuse them & read only what is really needed.
// This is typically the case of incremental reading of data.
// If no bytes exist in buffer -- full pread.
Status s;
uint64_t chunk_offset_in_buffer = 0;
uint64_t chunk_len = 0;
bool copy_data_to_new_buffer = false;
if (buffer_.CurrentSize() > 0 && offset >= buffer_offset_ &&
offset <= buffer_offset_ + buffer_.CurrentSize()) {
if (offset + n <= buffer_offset_ + buffer_.CurrentSize()) {
Improve direct IO range scan performance with readahead (#3884) Summary: This PR extends the improvements in #3282 to also work when using Direct IO. We see **4.5X performance improvement** in seekrandom benchmark doing long range scans, when using direct reads, on flash. **Description:** This change improves the performance of iterators doing long range scans (e.g. big/full index or table scans in MyRocks) by using readahead and prefetching additional data on each disk IO, and storing in a local buffer. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan. **Implementation Details:** - Used `FilePrefetchBuffer` as the underlying buffer to store the readahead data. `FilePrefetchBuffer` can now take file_reader, readahead_size and max_readahead_size as input to the constructor, and automatically do readahead. - `FilePrefetchBuffer::TryReadFromCache` can now call `FilePrefetchBuffer::Prefetch` if readahead is enabled. - `AlignedBuffer` (which is the underlying store for `FilePrefetchBuffer`) now takes a few additional args in `AlignedBuffer::AllocateNewBuffer` to allow copying data from the old buffer. - Made sure not to re-read partial chunks of data that were already available in the buffer, from device again. - Fixed a couple of cases where `AlignedBuffer::cursize_` was not being properly kept up-to-date. **Constraints:** - Similar to #3282, this gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value). - Since the prefetched data is stored in a temporary buffer allocated on heap, this could increase the memory usage if you have many iterators doing long range scans simultaneously. - Enabled only for user reads, and disabled for compactions. Compaction reads are controlled by the options `use_direct_io_for_flush_and_compaction` and `compaction_readahead_size`, and the current feature takes precautions not to mess with them. **Benchmarks:** I used the same benchmark as used in #3282. Data fill: ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes ``` Do a long range scan: Seekrandom with large number of nexts ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -use_direct_reads -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram ``` ``` Before: seekrandom : 37939.906 micros/op 26 ops/sec; 29.2 MB/s (1636 of 1999 found) With this change: seekrandom : 8527.720 micros/op 117 ops/sec; 129.7 MB/s (6530 of 7999 found) ``` ~4.5X perf improvement. Taken on an average of 3 runs. Closes https://github.com/facebook/rocksdb/pull/3884 Differential Revision: D8082143 Pulled By: sagar0 fbshipit-source-id: 4d7a8561cbac03478663713df4d31ad2620253bb
6 years ago
// All requested bytes are already in the buffer. So no need to Read
// again.
return s;
} else {
// Only a few requested bytes are in the buffer. memmove those chunk of
// bytes to the beginning, and memcpy them back into the new buffer if a
// new buffer is created.
chunk_offset_in_buffer = Rounddown(static_cast<size_t>(offset - buffer_offset_), alignment);
chunk_len = buffer_.CurrentSize() - chunk_offset_in_buffer;
Improve direct IO range scan performance with readahead (#3884) Summary: This PR extends the improvements in #3282 to also work when using Direct IO. We see **4.5X performance improvement** in seekrandom benchmark doing long range scans, when using direct reads, on flash. **Description:** This change improves the performance of iterators doing long range scans (e.g. big/full index or table scans in MyRocks) by using readahead and prefetching additional data on each disk IO, and storing in a local buffer. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan. **Implementation Details:** - Used `FilePrefetchBuffer` as the underlying buffer to store the readahead data. `FilePrefetchBuffer` can now take file_reader, readahead_size and max_readahead_size as input to the constructor, and automatically do readahead. - `FilePrefetchBuffer::TryReadFromCache` can now call `FilePrefetchBuffer::Prefetch` if readahead is enabled. - `AlignedBuffer` (which is the underlying store for `FilePrefetchBuffer`) now takes a few additional args in `AlignedBuffer::AllocateNewBuffer` to allow copying data from the old buffer. - Made sure not to re-read partial chunks of data that were already available in the buffer, from device again. - Fixed a couple of cases where `AlignedBuffer::cursize_` was not being properly kept up-to-date. **Constraints:** - Similar to #3282, this gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value). - Since the prefetched data is stored in a temporary buffer allocated on heap, this could increase the memory usage if you have many iterators doing long range scans simultaneously. - Enabled only for user reads, and disabled for compactions. Compaction reads are controlled by the options `use_direct_io_for_flush_and_compaction` and `compaction_readahead_size`, and the current feature takes precautions not to mess with them. **Benchmarks:** I used the same benchmark as used in #3282. Data fill: ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes ``` Do a long range scan: Seekrandom with large number of nexts ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -use_direct_reads -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram ``` ``` Before: seekrandom : 37939.906 micros/op 26 ops/sec; 29.2 MB/s (1636 of 1999 found) With this change: seekrandom : 8527.720 micros/op 117 ops/sec; 129.7 MB/s (6530 of 7999 found) ``` ~4.5X perf improvement. Taken on an average of 3 runs. Closes https://github.com/facebook/rocksdb/pull/3884 Differential Revision: D8082143 Pulled By: sagar0 fbshipit-source-id: 4d7a8561cbac03478663713df4d31ad2620253bb
6 years ago
assert(chunk_offset_in_buffer % alignment == 0);
assert(chunk_len % alignment == 0);
assert(chunk_offset_in_buffer + chunk_len <=
buffer_offset_ + buffer_.CurrentSize());
if (chunk_len > 0) {
copy_data_to_new_buffer = true;
} else {
// this reset is not necessary, but just to be safe.
chunk_offset_in_buffer = 0;
}
Improve direct IO range scan performance with readahead (#3884) Summary: This PR extends the improvements in #3282 to also work when using Direct IO. We see **4.5X performance improvement** in seekrandom benchmark doing long range scans, when using direct reads, on flash. **Description:** This change improves the performance of iterators doing long range scans (e.g. big/full index or table scans in MyRocks) by using readahead and prefetching additional data on each disk IO, and storing in a local buffer. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan. **Implementation Details:** - Used `FilePrefetchBuffer` as the underlying buffer to store the readahead data. `FilePrefetchBuffer` can now take file_reader, readahead_size and max_readahead_size as input to the constructor, and automatically do readahead. - `FilePrefetchBuffer::TryReadFromCache` can now call `FilePrefetchBuffer::Prefetch` if readahead is enabled. - `AlignedBuffer` (which is the underlying store for `FilePrefetchBuffer`) now takes a few additional args in `AlignedBuffer::AllocateNewBuffer` to allow copying data from the old buffer. - Made sure not to re-read partial chunks of data that were already available in the buffer, from device again. - Fixed a couple of cases where `AlignedBuffer::cursize_` was not being properly kept up-to-date. **Constraints:** - Similar to #3282, this gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value). - Since the prefetched data is stored in a temporary buffer allocated on heap, this could increase the memory usage if you have many iterators doing long range scans simultaneously. - Enabled only for user reads, and disabled for compactions. Compaction reads are controlled by the options `use_direct_io_for_flush_and_compaction` and `compaction_readahead_size`, and the current feature takes precautions not to mess with them. **Benchmarks:** I used the same benchmark as used in #3282. Data fill: ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes ``` Do a long range scan: Seekrandom with large number of nexts ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -use_direct_reads -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram ``` ``` Before: seekrandom : 37939.906 micros/op 26 ops/sec; 29.2 MB/s (1636 of 1999 found) With this change: seekrandom : 8527.720 micros/op 117 ops/sec; 129.7 MB/s (6530 of 7999 found) ``` ~4.5X perf improvement. Taken on an average of 3 runs. Closes https://github.com/facebook/rocksdb/pull/3884 Differential Revision: D8082143 Pulled By: sagar0 fbshipit-source-id: 4d7a8561cbac03478663713df4d31ad2620253bb
6 years ago
}
}
// Create a new buffer only if current capacity is not sufficient, and memcopy
// bytes from old buffer if needed (i.e., if chunk_len is greater than 0).
if (buffer_.Capacity() < roundup_len) {
buffer_.Alignment(alignment);
buffer_.AllocateNewBuffer(static_cast<size_t>(roundup_len),
copy_data_to_new_buffer, chunk_offset_in_buffer,
static_cast<size_t>(chunk_len));
Improve direct IO range scan performance with readahead (#3884) Summary: This PR extends the improvements in #3282 to also work when using Direct IO. We see **4.5X performance improvement** in seekrandom benchmark doing long range scans, when using direct reads, on flash. **Description:** This change improves the performance of iterators doing long range scans (e.g. big/full index or table scans in MyRocks) by using readahead and prefetching additional data on each disk IO, and storing in a local buffer. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan. **Implementation Details:** - Used `FilePrefetchBuffer` as the underlying buffer to store the readahead data. `FilePrefetchBuffer` can now take file_reader, readahead_size and max_readahead_size as input to the constructor, and automatically do readahead. - `FilePrefetchBuffer::TryReadFromCache` can now call `FilePrefetchBuffer::Prefetch` if readahead is enabled. - `AlignedBuffer` (which is the underlying store for `FilePrefetchBuffer`) now takes a few additional args in `AlignedBuffer::AllocateNewBuffer` to allow copying data from the old buffer. - Made sure not to re-read partial chunks of data that were already available in the buffer, from device again. - Fixed a couple of cases where `AlignedBuffer::cursize_` was not being properly kept up-to-date. **Constraints:** - Similar to #3282, this gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value). - Since the prefetched data is stored in a temporary buffer allocated on heap, this could increase the memory usage if you have many iterators doing long range scans simultaneously. - Enabled only for user reads, and disabled for compactions. Compaction reads are controlled by the options `use_direct_io_for_flush_and_compaction` and `compaction_readahead_size`, and the current feature takes precautions not to mess with them. **Benchmarks:** I used the same benchmark as used in #3282. Data fill: ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes ``` Do a long range scan: Seekrandom with large number of nexts ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -use_direct_reads -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram ``` ``` Before: seekrandom : 37939.906 micros/op 26 ops/sec; 29.2 MB/s (1636 of 1999 found) With this change: seekrandom : 8527.720 micros/op 117 ops/sec; 129.7 MB/s (6530 of 7999 found) ``` ~4.5X perf improvement. Taken on an average of 3 runs. Closes https://github.com/facebook/rocksdb/pull/3884 Differential Revision: D8082143 Pulled By: sagar0 fbshipit-source-id: 4d7a8561cbac03478663713df4d31ad2620253bb
6 years ago
} else if (chunk_len > 0) {
// New buffer not needed. But memmove bytes from tail to the beginning since
// chunk_len is greater than 0.
buffer_.RefitTail(static_cast<size_t>(chunk_offset_in_buffer), static_cast<size_t>(chunk_len));
Improve direct IO range scan performance with readahead (#3884) Summary: This PR extends the improvements in #3282 to also work when using Direct IO. We see **4.5X performance improvement** in seekrandom benchmark doing long range scans, when using direct reads, on flash. **Description:** This change improves the performance of iterators doing long range scans (e.g. big/full index or table scans in MyRocks) by using readahead and prefetching additional data on each disk IO, and storing in a local buffer. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan. **Implementation Details:** - Used `FilePrefetchBuffer` as the underlying buffer to store the readahead data. `FilePrefetchBuffer` can now take file_reader, readahead_size and max_readahead_size as input to the constructor, and automatically do readahead. - `FilePrefetchBuffer::TryReadFromCache` can now call `FilePrefetchBuffer::Prefetch` if readahead is enabled. - `AlignedBuffer` (which is the underlying store for `FilePrefetchBuffer`) now takes a few additional args in `AlignedBuffer::AllocateNewBuffer` to allow copying data from the old buffer. - Made sure not to re-read partial chunks of data that were already available in the buffer, from device again. - Fixed a couple of cases where `AlignedBuffer::cursize_` was not being properly kept up-to-date. **Constraints:** - Similar to #3282, this gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value). - Since the prefetched data is stored in a temporary buffer allocated on heap, this could increase the memory usage if you have many iterators doing long range scans simultaneously. - Enabled only for user reads, and disabled for compactions. Compaction reads are controlled by the options `use_direct_io_for_flush_and_compaction` and `compaction_readahead_size`, and the current feature takes precautions not to mess with them. **Benchmarks:** I used the same benchmark as used in #3282. Data fill: ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes ``` Do a long range scan: Seekrandom with large number of nexts ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -use_direct_reads -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram ``` ``` Before: seekrandom : 37939.906 micros/op 26 ops/sec; 29.2 MB/s (1636 of 1999 found) With this change: seekrandom : 8527.720 micros/op 117 ops/sec; 129.7 MB/s (6530 of 7999 found) ``` ~4.5X perf improvement. Taken on an average of 3 runs. Closes https://github.com/facebook/rocksdb/pull/3884 Differential Revision: D8082143 Pulled By: sagar0 fbshipit-source-id: 4d7a8561cbac03478663713df4d31ad2620253bb
6 years ago
}
Slice result;
Improve direct IO range scan performance with readahead (#3884) Summary: This PR extends the improvements in #3282 to also work when using Direct IO. We see **4.5X performance improvement** in seekrandom benchmark doing long range scans, when using direct reads, on flash. **Description:** This change improves the performance of iterators doing long range scans (e.g. big/full index or table scans in MyRocks) by using readahead and prefetching additional data on each disk IO, and storing in a local buffer. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan. **Implementation Details:** - Used `FilePrefetchBuffer` as the underlying buffer to store the readahead data. `FilePrefetchBuffer` can now take file_reader, readahead_size and max_readahead_size as input to the constructor, and automatically do readahead. - `FilePrefetchBuffer::TryReadFromCache` can now call `FilePrefetchBuffer::Prefetch` if readahead is enabled. - `AlignedBuffer` (which is the underlying store for `FilePrefetchBuffer`) now takes a few additional args in `AlignedBuffer::AllocateNewBuffer` to allow copying data from the old buffer. - Made sure not to re-read partial chunks of data that were already available in the buffer, from device again. - Fixed a couple of cases where `AlignedBuffer::cursize_` was not being properly kept up-to-date. **Constraints:** - Similar to #3282, this gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value). - Since the prefetched data is stored in a temporary buffer allocated on heap, this could increase the memory usage if you have many iterators doing long range scans simultaneously. - Enabled only for user reads, and disabled for compactions. Compaction reads are controlled by the options `use_direct_io_for_flush_and_compaction` and `compaction_readahead_size`, and the current feature takes precautions not to mess with them. **Benchmarks:** I used the same benchmark as used in #3282. Data fill: ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes ``` Do a long range scan: Seekrandom with large number of nexts ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -use_direct_reads -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram ``` ``` Before: seekrandom : 37939.906 micros/op 26 ops/sec; 29.2 MB/s (1636 of 1999 found) With this change: seekrandom : 8527.720 micros/op 117 ops/sec; 129.7 MB/s (6530 of 7999 found) ``` ~4.5X perf improvement. Taken on an average of 3 runs. Closes https://github.com/facebook/rocksdb/pull/3884 Differential Revision: D8082143 Pulled By: sagar0 fbshipit-source-id: 4d7a8561cbac03478663713df4d31ad2620253bb
6 years ago
s = reader->Read(rounddown_offset + chunk_len,
static_cast<size_t>(roundup_len - chunk_len), &result,
buffer_.BufferStart() + chunk_len, for_compaction);
if (s.ok()) {
buffer_offset_ = rounddown_offset;
buffer_.Size(static_cast<size_t>(chunk_len) + result.size());
}
return s;
}
bool FilePrefetchBuffer::TryReadFromCache(uint64_t offset, size_t n,
Slice* result, bool for_compaction) {
if (track_min_offset_ && offset < min_offset_read_) {
min_offset_read_ = static_cast<size_t>(offset);
}
if (!enable_ || offset < buffer_offset_) {
return false;
}
Improve direct IO range scan performance with readahead (#3884) Summary: This PR extends the improvements in #3282 to also work when using Direct IO. We see **4.5X performance improvement** in seekrandom benchmark doing long range scans, when using direct reads, on flash. **Description:** This change improves the performance of iterators doing long range scans (e.g. big/full index or table scans in MyRocks) by using readahead and prefetching additional data on each disk IO, and storing in a local buffer. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan. **Implementation Details:** - Used `FilePrefetchBuffer` as the underlying buffer to store the readahead data. `FilePrefetchBuffer` can now take file_reader, readahead_size and max_readahead_size as input to the constructor, and automatically do readahead. - `FilePrefetchBuffer::TryReadFromCache` can now call `FilePrefetchBuffer::Prefetch` if readahead is enabled. - `AlignedBuffer` (which is the underlying store for `FilePrefetchBuffer`) now takes a few additional args in `AlignedBuffer::AllocateNewBuffer` to allow copying data from the old buffer. - Made sure not to re-read partial chunks of data that were already available in the buffer, from device again. - Fixed a couple of cases where `AlignedBuffer::cursize_` was not being properly kept up-to-date. **Constraints:** - Similar to #3282, this gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value). - Since the prefetched data is stored in a temporary buffer allocated on heap, this could increase the memory usage if you have many iterators doing long range scans simultaneously. - Enabled only for user reads, and disabled for compactions. Compaction reads are controlled by the options `use_direct_io_for_flush_and_compaction` and `compaction_readahead_size`, and the current feature takes precautions not to mess with them. **Benchmarks:** I used the same benchmark as used in #3282. Data fill: ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes ``` Do a long range scan: Seekrandom with large number of nexts ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -use_direct_reads -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram ``` ``` Before: seekrandom : 37939.906 micros/op 26 ops/sec; 29.2 MB/s (1636 of 1999 found) With this change: seekrandom : 8527.720 micros/op 117 ops/sec; 129.7 MB/s (6530 of 7999 found) ``` ~4.5X perf improvement. Taken on an average of 3 runs. Closes https://github.com/facebook/rocksdb/pull/3884 Differential Revision: D8082143 Pulled By: sagar0 fbshipit-source-id: 4d7a8561cbac03478663713df4d31ad2620253bb
6 years ago
// If the buffer contains only a few of the requested bytes:
// If readahead is enabled: prefetch the remaining bytes + readadhead bytes
// and satisfy the request.
// If readahead is not enabled: return false.
if (offset + n > buffer_offset_ + buffer_.CurrentSize()) {
Improve direct IO range scan performance with readahead (#3884) Summary: This PR extends the improvements in #3282 to also work when using Direct IO. We see **4.5X performance improvement** in seekrandom benchmark doing long range scans, when using direct reads, on flash. **Description:** This change improves the performance of iterators doing long range scans (e.g. big/full index or table scans in MyRocks) by using readahead and prefetching additional data on each disk IO, and storing in a local buffer. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan. **Implementation Details:** - Used `FilePrefetchBuffer` as the underlying buffer to store the readahead data. `FilePrefetchBuffer` can now take file_reader, readahead_size and max_readahead_size as input to the constructor, and automatically do readahead. - `FilePrefetchBuffer::TryReadFromCache` can now call `FilePrefetchBuffer::Prefetch` if readahead is enabled. - `AlignedBuffer` (which is the underlying store for `FilePrefetchBuffer`) now takes a few additional args in `AlignedBuffer::AllocateNewBuffer` to allow copying data from the old buffer. - Made sure not to re-read partial chunks of data that were already available in the buffer, from device again. - Fixed a couple of cases where `AlignedBuffer::cursize_` was not being properly kept up-to-date. **Constraints:** - Similar to #3282, this gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value). - Since the prefetched data is stored in a temporary buffer allocated on heap, this could increase the memory usage if you have many iterators doing long range scans simultaneously. - Enabled only for user reads, and disabled for compactions. Compaction reads are controlled by the options `use_direct_io_for_flush_and_compaction` and `compaction_readahead_size`, and the current feature takes precautions not to mess with them. **Benchmarks:** I used the same benchmark as used in #3282. Data fill: ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes ``` Do a long range scan: Seekrandom with large number of nexts ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -use_direct_reads -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram ``` ``` Before: seekrandom : 37939.906 micros/op 26 ops/sec; 29.2 MB/s (1636 of 1999 found) With this change: seekrandom : 8527.720 micros/op 117 ops/sec; 129.7 MB/s (6530 of 7999 found) ``` ~4.5X perf improvement. Taken on an average of 3 runs. Closes https://github.com/facebook/rocksdb/pull/3884 Differential Revision: D8082143 Pulled By: sagar0 fbshipit-source-id: 4d7a8561cbac03478663713df4d31ad2620253bb
6 years ago
if (readahead_size_ > 0) {
assert(file_reader_ != nullptr);
assert(max_readahead_size_ >= readahead_size_);
Compaction Reads should read no more than compaction_readahead_size bytes, when set! (#5498) Summary: As a result of https://github.com/facebook/rocksdb/issues/5431 the compaction_readahead_size given by a user was not used exactly, the reason being the code behind readahead for user-read and compaction-read was unified in the above PR and the behavior for user-read is to read readahead_size+n bytes (see FilePrefetchBuffer::TryReadFromCache method). Before the unification the ReadaheadRandomAccessFileReader used compaction_readahead_size as it is. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5498 Test Plan: Ran strace command : strace -e pread64 -f -T -t ./db_compaction_test --gtest_filter=DBCompactionTest.PartialManualCompaction In the test the compaction_readahead_size was configured to 2MB and verified the pread syscall did indeed request 2MB. Before the change it was requesting more than 2MB. Strace Output: strace: Process 3798982 attached Note: Google Test filter = DBCompactionTest.PartialManualCompaction [==========] Running 1 test from 1 test case. [----------] Global test environment set-up. [----------] 1 test from DBCompactionTest [ RUN ] DBCompactionTest.PartialManualCompaction strace: Process 3798983 attached strace: Process 3798984 attached strace: Process 3798985 attached strace: Process 3798986 attached strace: Process 3798987 attached strace: Process 3798992 attached [pid 3798987] 12:07:05 +++ exited with 0 +++ strace: Process 3798993 attached [pid 3798993] 12:07:05 +++ exited with 0 +++ strace: Process 3798994 attached strace: Process 3799008 attached strace: Process 3799009 attached [pid 3799008] 12:07:05 +++ exited with 0 +++ strace: Process 3799010 attached [pid 3799009] 12:07:05 +++ exited with 0 +++ strace: Process 3799011 attached [pid 3799010] 12:07:05 +++ exited with 0 +++ [pid 3799011] 12:07:05 +++ exited with 0 +++ strace: Process 3799012 attached [pid 3799012] 12:07:05 +++ exited with 0 +++ strace: Process 3799013 attached strace: Process 3799014 attached [pid 3799013] 12:07:05 +++ exited with 0 +++ strace: Process 3799015 attached [pid 3799014] 12:07:05 +++ exited with 0 +++ [pid 3799015] 12:07:05 +++ exited with 0 +++ strace: Process 3799016 attached [pid 3799016] 12:07:05 +++ exited with 0 +++ strace: Process 3799017 attached [pid 3799017] 12:07:05 +++ exited with 0 +++ strace: Process 3799019 attached [pid 3799019] 12:07:05 +++ exited with 0 +++ strace: Process 3799020 attached strace: Process 3799021 attached [pid 3799020] 12:07:05 +++ exited with 0 +++ [pid 3799021] 12:07:05 +++ exited with 0 +++ strace: Process 3799022 attached [pid 3799022] 12:07:05 +++ exited with 0 +++ strace: Process 3799023 attached [pid 3799023] 12:07:05 +++ exited with 0 +++ strace: Process 3799047 attached strace: Process 3799048 attached [pid 3799047] 12:07:06 +++ exited with 0 +++ [pid 3799048] 12:07:06 +++ exited with 0 +++ [pid 3798994] 12:07:06 +++ exited with 0 +++ strace: Process 3799052 attached [pid 3799052] 12:07:06 +++ exited with 0 +++ strace: Process 3799054 attached strace: Process 3799069 attached strace: Process 3799070 attached [pid 3799069] 12:07:06 +++ exited with 0 +++ strace: Process 3799071 attached [pid 3799070] 12:07:06 +++ exited with 0 +++ [pid 3799071] 12:07:06 +++ exited with 0 +++ strace: Process 3799072 attached strace: Process 3799073 attached [pid 3799072] 12:07:06 +++ exited with 0 +++ [pid 3799073] 12:07:06 +++ exited with 0 +++ strace: Process 3799074 attached [pid 3799074] 12:07:06 +++ exited with 0 +++ strace: Process 3799075 attached [pid 3799075] 12:07:06 +++ exited with 0 +++ strace: Process 3799076 attached [pid 3799076] 12:07:06 +++ exited with 0 +++ strace: Process 3799077 attached [pid 3799077] 12:07:06 +++ exited with 0 +++ strace: Process 3799078 attached [pid 3799078] 12:07:06 +++ exited with 0 +++ strace: Process 3799079 attached [pid 3799079] 12:07:06 +++ exited with 0 +++ strace: Process 3799080 attached [pid 3799080] 12:07:06 +++ exited with 0 +++ strace: Process 3799081 attached [pid 3799081] 12:07:06 +++ exited with 0 +++ strace: Process 3799082 attached [pid 3799082] 12:07:06 +++ exited with 0 +++ strace: Process 3799083 attached [pid 3799083] 12:07:06 +++ exited with 0 +++ strace: Process 3799086 attached strace: Process 3799087 attached [pid 3798984] 12:07:06 pread64(9, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000121> [pid 3798984] 12:07:06 pread64(9, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000106> [pid 3798984] 12:07:06 pread64(9, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000081> [pid 3798984] 12:07:06 pread64(9, "\0\v\3foo\2\7\0\0\0\0\0\0\0\270 \0\v\4foo\2\3\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000138> [pid 3798984] 12:07:06 pread64(11, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000097> [pid 3798984] 12:07:06 pread64(11, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000086> [pid 3798984] 12:07:06 pread64(11, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000064> [pid 3798984] 12:07:06 pread64(11, "\0\v\3foo\2\21\0\0\0\0\0\0\0\270 \0\v\4foo\2\r\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000064> [pid 3798984] 12:07:06 pread64(12, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000080> [pid 3798984] 12:07:06 pread64(12, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000090> [pid 3798984] 12:07:06 pread64(12, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000059> [pid 3798984] 12:07:06 pread64(12, "\0\v\3foo\2\33\0\0\0\0\0\0\0\270 \0\v\4foo\2\27\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000065> [pid 3798984] 12:07:06 pread64(13, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000070> [pid 3798984] 12:07:06 pread64(13, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000059> [pid 3798984] 12:07:06 pread64(13, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000061> [pid 3798984] 12:07:06 pread64(13, "\0\v\3foo\2%\0\0\0\0\0\0\0\270 \0\v\4foo\2!\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000065> [pid 3798984] 12:07:06 pread64(14, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000118> [pid 3798984] 12:07:06 pread64(14, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000093> [pid 3798984] 12:07:06 pread64(14, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000050> [pid 3798984] 12:07:06 pread64(14, "\0\v\3foo\2/\0\0\0\0\0\0\0\270 \0\v\4foo\2+\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000082> [pid 3798984] 12:07:06 pread64(15, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000080> [pid 3798984] 12:07:06 pread64(15, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000086> [pid 3798984] 12:07:06 pread64(15, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000091> [pid 3798984] 12:07:06 pread64(15, "\0\v\3foo\0029\0\0\0\0\0\0\0\270 \0\v\4foo\0025\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000174> [pid 3798984] 12:07:06 pread64(16, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000080> [pid 3798984] 12:07:06 pread64(16, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000093> [pid 3798984] 12:07:06 pread64(16, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000194> [pid 3798984] 12:07:06 pread64(16, "\0\v\3foo\2C\0\0\0\0\0\0\0\270 \0\v\4foo\2?\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000086> [pid 3798984] 12:07:06 pread64(17, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000079> [pid 3798984] 12:07:06 pread64(17, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000047> [pid 3798984] 12:07:06 pread64(17, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000045> [pid 3798984] 12:07:06 pread64(17, "\0\v\3foo\2M\0\0\0\0\0\0\0\270 \0\v\4foo\2I\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000107> [pid 3798983] 12:07:06 pread64(17, "\0\v\200\10foo\2P\0\0\0\0\0\0)U?MSg_)j(roFn($e"..., 2097152, 0) = 11230 <0.000091> [pid 3798983] 12:07:06 pread64(17, "", 2085922, 11230) = 0 <0.000073> [pid 3798983] 12:07:06 pread64(16, "\0\v\200\10foo\2F\0\0\0\0\0\0k[h3%.OPH_^:\\S7T&"..., 2097152, 0) = 11230 <0.000083> [pid 3798983] 12:07:06 pread64(16, "", 2085922, 11230) = 0 <0.000078> [pid 3798983] 12:07:06 pread64(15, "\0\v\200\10foo\2<\0\0\0\0\0\0+qToi_c{*S+4:N(:"..., 2097152, 0) = 11230 <0.000095> [pid 3798983] 12:07:06 pread64(15, "", 2085922, 11230) = 0 <0.000067> [pid 3798983] 12:07:06 pread64(14, "\0\v\200\10foo\0022\0\0\0\0\0\0%hw%OMa\"}9I609Q!B"..., 2097152, 0) = 11230 <0.000111> [pid 3798983] 12:07:06 pread64(14, "", 2085922, 11230) = 0 <0.000093> [pid 3798983] 12:07:06 pread64(13, "\0\v\200\10foo\2(\0\0\0\0\0\0p}Y&mu^DcaSGb2&nP"..., 2097152, 0) = 11230 <0.000128> [pid 3798983] 12:07:06 pread64(13, "", 2085922, 11230) = 0 <0.000076> [pid 3798983] 12:07:06 pread64(12, "\0\v\200\10foo\2\36\0\0\0\0\0\0YIyW#]oSs^6VHfB<`"..., 2097152, 0) = 11230 <0.000092> [pid 3798983] 12:07:06 pread64(12, "", 2085922, 11230) = 0 <0.000073> [pid 3798983] 12:07:06 pread64(11, "\0\v\200\10foo\2\24\0\0\0\0\0\0mfF8Jel/*Zf :-#s("..., 2097152, 0) = 11230 <0.000088> [pid 3798983] 12:07:06 pread64(11, "", 2085922, 11230) = 0 <0.000067> [pid 3798983] 12:07:06 pread64(9, "\0\v\200\10foo\2\n\0\0\0\0\0\0\\X'cjiHX)D,RSj1X!"..., 2097152, 0) = 11230 <0.000115> [pid 3798983] 12:07:06 pread64(9, "", 2085922, 11230) = 0 <0.000073> [pid 3798983] 12:07:06 pread64(8, "\1\315\5 \36\30\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 754) = 53 <0.000098> [pid 3798983] 12:07:06 pread64(8, "\0\22\3rocksdb.properties;\215\5\0\0\0\0\1\0\0\0"..., 37, 717) = 37 <0.000064> [pid 3798983] 12:07:06 pread64(8, "\0$\4rocksdb.block.based.table.ind"..., 658, 59) = 658 <0.000074> [pid 3798983] 12:07:06 pread64(8, "\0\v\2foo\1\0\0\0\0\0\0\0\0\31\0\0\0\0\1\0\0\0\0\212\216\222P", 29, 30) = 29 <0.000064> [pid 3799086] 12:07:06 +++ exited with 0 +++ [pid 3799087] 12:07:06 +++ exited with 0 +++ [pid 3799054] 12:07:06 +++ exited with 0 +++ strace: Process 3799104 attached [pid 3799104] 12:07:06 +++ exited with 0 +++ [ OK ] DBCompactionTest.PartialManualCompaction (757 ms) [----------] 1 test from DBCompactionTest (758 ms total) [----------] Global test environment tear-down [==========] 1 test from 1 test case ran. (759 ms total) [ PASSED ] 1 test. [pid 3798983] 12:07:06 +++ exited with 0 +++ [pid 3798984] 12:07:06 +++ exited with 0 +++ [pid 3798992] 12:07:06 +++ exited with 0 +++ [pid 3798986] 12:07:06 +++ exited with 0 +++ [pid 3798982] 12:07:06 +++ exited with 0 +++ [pid 3798985] 12:07:06 +++ exited with 0 +++ 12:07:06 +++ exited with 0 +++ Differential Revision: D15948422 Pulled By: vjnadimpalli fbshipit-source-id: 9b189d1e8675d290c7784e4b33e5d3b5761d2ac8
5 years ago
Status s;
if (for_compaction) {
Fix a bug in compaction reads causing checksum mismatches and asan errors (#5531) Summary: Fixed a bug in compaction reads due to which incorrect number of bytes were being read/utilized. The bug was introduced in https://github.com/facebook/rocksdb/issues/5498 , resulting in "Corruption: block checksum mismatch" and "heap-buffer-overflow" asan errors in our tests. https://github.com/facebook/rocksdb/issues/5498 was introduced recently and is not in any released versions. ASAN: ``` > ==2280939==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6250005e83da at pc 0x000000d57f62 bp 0x7f954f483770 sp 0x7f954f482f20 > === How to use this, how to get the raw stack trace, and more: fburl.com/ASAN === > READ of size 4 at 0x6250005e83da thread T4 > SCARINESS: 27 (4-byte-read-heap-buffer-overflow-far-from-bounds) > #0 tests+0xd57f61 __asan_memcpy > https://github.com/facebook/rocksdb/issues/1 rocksdb/src/util/coding.h:124 rocksdb::DecodeFixed32(char const*) > https://github.com/facebook/rocksdb/issues/2 rocksdb/src/table/block_fetcher.cc:39 rocksdb::BlockFetcher::CheckBlockChecksum() > https://github.com/facebook/rocksdb/issues/3 rocksdb/src/table/block_fetcher.cc:99 rocksdb::BlockFetcher::TryGetFromPrefetchBuffer() > https://github.com/facebook/rocksdb/issues/4 rocksdb/src/table/block_fetcher.cc:209 rocksdb::BlockFetcher::ReadBlockContents() > https://github.com/facebook/rocksdb/issues/5 rocksdb/src/table/block_based/block_based_table_reader.cc:93 rocksdb::(anonymous namespace)::ReadBlockFromFile(rocksdb::RandomAccessFileReader*, rocksdb::FilePrefetchBuffer*, rocksdb::Footer const&, rocksdb::ReadOptions const&, rocksdb::BlockHandle const&, std::unique_ptr<...>*, rocksdb::ImmutableCFOptions const&, bool, bool, rocksdb::UncompressionDict const&, rocksdb::PersistentCacheOptions const&, unsigned long, unsigned long, rocksdb::MemoryAllocator*, bool) > https://github.com/facebook/rocksdb/issues/6 rocksdb/src/table/block_based/block_based_table_reader.cc:2331 rocksdb::BlockBasedTable::RetrieveBlock(rocksdb::FilePrefetchBuffer*, rocksdb::ReadOptions const&, rocksdb::BlockHandle const&, rocksdb::UncompressionDict const&, rocksdb::CachableEntry<...>*, rocksdb::BlockType, rocksdb::GetContext*, rocksdb::BlockCacheLookupContext*, bool) const > https://github.com/facebook/rocksdb/issues/7 rocksdb/src/table/block_based/block_based_table_reader.cc:2090 rocksdb::DataBlockIter* rocksdb::BlockBasedTable::NewDataBlockIterator<...>(rocksdb::ReadOptions const&, rocksdb::BlockHandle const&, rocksdb::DataBlockIter*, rocksdb::BlockType, bool, bool, rocksdb::GetContext*, rocksdb::BlockCacheLookupContext*, rocksdb::Status, rocksdb::FilePrefetchBuffe r*, bool) const > https://github.com/facebook/rocksdb/issues/8 rocksdb/src/table/block_based/block_based_table_reader.cc:2720 rocksdb::BlockBasedTableIterator<...>::InitDataBlock() > https://github.com/facebook/rocksdb/issues/9 rocksdb/src/table/block_based/block_based_table_reader.cc:2607 rocksdb::BlockBasedTableIterator<...>::SeekToFirst() > https://github.com/facebook/rocksdb/issues/10 rocksdb/src/table/iterator_wrapper.h:83 rocksdb::IteratorWrapperBase<...>::SeekToFirst() > https://github.com/facebook/rocksdb/issues/11 rocksdb/src/table/merging_iterator.cc:100 rocksdb::MergingIterator::SeekToFirst() > https://github.com/facebook/rocksdb/issues/12 rocksdb/compaction/compaction_job.cc:877 rocksdb::CompactionJob::ProcessKeyValueCompaction(rocksdb::CompactionJob::SubcompactionState*) > https://github.com/facebook/rocksdb/issues/13 rocksdb/compaction/compaction_job.cc:590 rocksdb::CompactionJob::Run() > https://github.com/facebook/rocksdb/issues/14 rocksdb/db_impl/db_impl_compaction_flush.cc:2689 rocksdb::DBImpl::BackgroundCompaction(bool*, rocksdb::JobContext*, rocksdb::LogBuffer*, rocksdb::DBImpl::PrepickedCompaction*, rocksdb::Env::Priority) > https://github.com/facebook/rocksdb/issues/15 rocksdb/db_impl/db_impl_compaction_flush.cc:2248 rocksdb::DBImpl::BackgroundCallCompaction(rocksdb::DBImpl::PrepickedCompaction*, rocksdb::Env::Priority) > https://github.com/facebook/rocksdb/issues/16 rocksdb/db_impl/db_impl_compaction_flush.cc:2024 rocksdb::DBImpl::BGWorkCompaction(void*) > https://github.com/facebook/rocksdb/issues/23 rocksdb/src/util/threadpool_imp.cc:266 rocksdb::ThreadPoolImpl::Impl::BGThread(unsigned long) > https://github.com/facebook/rocksdb/issues/24 rocksdb/src/util/threadpool_imp.cc:307 rocksdb::ThreadPoolImpl::Impl::BGThreadWrapper(void*) ``` Pull Request resolved: https://github.com/facebook/rocksdb/pull/5531 Test Plan: Verified that this fixes the fb-internal Logdevice test which caught the issue. Differential Revision: D16109702 Pulled By: sagar0 fbshipit-source-id: 1fc08549cf7b553e338a133ae11eb9f4d5011914
5 years ago
s = Prefetch(file_reader_, offset, std::max(n, readahead_size_), for_compaction);
Compaction Reads should read no more than compaction_readahead_size bytes, when set! (#5498) Summary: As a result of https://github.com/facebook/rocksdb/issues/5431 the compaction_readahead_size given by a user was not used exactly, the reason being the code behind readahead for user-read and compaction-read was unified in the above PR and the behavior for user-read is to read readahead_size+n bytes (see FilePrefetchBuffer::TryReadFromCache method). Before the unification the ReadaheadRandomAccessFileReader used compaction_readahead_size as it is. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5498 Test Plan: Ran strace command : strace -e pread64 -f -T -t ./db_compaction_test --gtest_filter=DBCompactionTest.PartialManualCompaction In the test the compaction_readahead_size was configured to 2MB and verified the pread syscall did indeed request 2MB. Before the change it was requesting more than 2MB. Strace Output: strace: Process 3798982 attached Note: Google Test filter = DBCompactionTest.PartialManualCompaction [==========] Running 1 test from 1 test case. [----------] Global test environment set-up. [----------] 1 test from DBCompactionTest [ RUN ] DBCompactionTest.PartialManualCompaction strace: Process 3798983 attached strace: Process 3798984 attached strace: Process 3798985 attached strace: Process 3798986 attached strace: Process 3798987 attached strace: Process 3798992 attached [pid 3798987] 12:07:05 +++ exited with 0 +++ strace: Process 3798993 attached [pid 3798993] 12:07:05 +++ exited with 0 +++ strace: Process 3798994 attached strace: Process 3799008 attached strace: Process 3799009 attached [pid 3799008] 12:07:05 +++ exited with 0 +++ strace: Process 3799010 attached [pid 3799009] 12:07:05 +++ exited with 0 +++ strace: Process 3799011 attached [pid 3799010] 12:07:05 +++ exited with 0 +++ [pid 3799011] 12:07:05 +++ exited with 0 +++ strace: Process 3799012 attached [pid 3799012] 12:07:05 +++ exited with 0 +++ strace: Process 3799013 attached strace: Process 3799014 attached [pid 3799013] 12:07:05 +++ exited with 0 +++ strace: Process 3799015 attached [pid 3799014] 12:07:05 +++ exited with 0 +++ [pid 3799015] 12:07:05 +++ exited with 0 +++ strace: Process 3799016 attached [pid 3799016] 12:07:05 +++ exited with 0 +++ strace: Process 3799017 attached [pid 3799017] 12:07:05 +++ exited with 0 +++ strace: Process 3799019 attached [pid 3799019] 12:07:05 +++ exited with 0 +++ strace: Process 3799020 attached strace: Process 3799021 attached [pid 3799020] 12:07:05 +++ exited with 0 +++ [pid 3799021] 12:07:05 +++ exited with 0 +++ strace: Process 3799022 attached [pid 3799022] 12:07:05 +++ exited with 0 +++ strace: Process 3799023 attached [pid 3799023] 12:07:05 +++ exited with 0 +++ strace: Process 3799047 attached strace: Process 3799048 attached [pid 3799047] 12:07:06 +++ exited with 0 +++ [pid 3799048] 12:07:06 +++ exited with 0 +++ [pid 3798994] 12:07:06 +++ exited with 0 +++ strace: Process 3799052 attached [pid 3799052] 12:07:06 +++ exited with 0 +++ strace: Process 3799054 attached strace: Process 3799069 attached strace: Process 3799070 attached [pid 3799069] 12:07:06 +++ exited with 0 +++ strace: Process 3799071 attached [pid 3799070] 12:07:06 +++ exited with 0 +++ [pid 3799071] 12:07:06 +++ exited with 0 +++ strace: Process 3799072 attached strace: Process 3799073 attached [pid 3799072] 12:07:06 +++ exited with 0 +++ [pid 3799073] 12:07:06 +++ exited with 0 +++ strace: Process 3799074 attached [pid 3799074] 12:07:06 +++ exited with 0 +++ strace: Process 3799075 attached [pid 3799075] 12:07:06 +++ exited with 0 +++ strace: Process 3799076 attached [pid 3799076] 12:07:06 +++ exited with 0 +++ strace: Process 3799077 attached [pid 3799077] 12:07:06 +++ exited with 0 +++ strace: Process 3799078 attached [pid 3799078] 12:07:06 +++ exited with 0 +++ strace: Process 3799079 attached [pid 3799079] 12:07:06 +++ exited with 0 +++ strace: Process 3799080 attached [pid 3799080] 12:07:06 +++ exited with 0 +++ strace: Process 3799081 attached [pid 3799081] 12:07:06 +++ exited with 0 +++ strace: Process 3799082 attached [pid 3799082] 12:07:06 +++ exited with 0 +++ strace: Process 3799083 attached [pid 3799083] 12:07:06 +++ exited with 0 +++ strace: Process 3799086 attached strace: Process 3799087 attached [pid 3798984] 12:07:06 pread64(9, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000121> [pid 3798984] 12:07:06 pread64(9, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000106> [pid 3798984] 12:07:06 pread64(9, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000081> [pid 3798984] 12:07:06 pread64(9, "\0\v\3foo\2\7\0\0\0\0\0\0\0\270 \0\v\4foo\2\3\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000138> [pid 3798984] 12:07:06 pread64(11, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000097> [pid 3798984] 12:07:06 pread64(11, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000086> [pid 3798984] 12:07:06 pread64(11, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000064> [pid 3798984] 12:07:06 pread64(11, "\0\v\3foo\2\21\0\0\0\0\0\0\0\270 \0\v\4foo\2\r\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000064> [pid 3798984] 12:07:06 pread64(12, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000080> [pid 3798984] 12:07:06 pread64(12, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000090> [pid 3798984] 12:07:06 pread64(12, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000059> [pid 3798984] 12:07:06 pread64(12, "\0\v\3foo\2\33\0\0\0\0\0\0\0\270 \0\v\4foo\2\27\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000065> [pid 3798984] 12:07:06 pread64(13, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000070> [pid 3798984] 12:07:06 pread64(13, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000059> [pid 3798984] 12:07:06 pread64(13, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000061> [pid 3798984] 12:07:06 pread64(13, "\0\v\3foo\2%\0\0\0\0\0\0\0\270 \0\v\4foo\2!\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000065> [pid 3798984] 12:07:06 pread64(14, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000118> [pid 3798984] 12:07:06 pread64(14, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000093> [pid 3798984] 12:07:06 pread64(14, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000050> [pid 3798984] 12:07:06 pread64(14, "\0\v\3foo\2/\0\0\0\0\0\0\0\270 \0\v\4foo\2+\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000082> [pid 3798984] 12:07:06 pread64(15, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000080> [pid 3798984] 12:07:06 pread64(15, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000086> [pid 3798984] 12:07:06 pread64(15, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000091> [pid 3798984] 12:07:06 pread64(15, "\0\v\3foo\0029\0\0\0\0\0\0\0\270 \0\v\4foo\0025\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000174> [pid 3798984] 12:07:06 pread64(16, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000080> [pid 3798984] 12:07:06 pread64(16, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000093> [pid 3798984] 12:07:06 pread64(16, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000194> [pid 3798984] 12:07:06 pread64(16, "\0\v\3foo\2C\0\0\0\0\0\0\0\270 \0\v\4foo\2?\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000086> [pid 3798984] 12:07:06 pread64(17, "\1\203W!\241QE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 11177) = 53 <0.000079> [pid 3798984] 12:07:06 pread64(17, "\0\22\4rocksdb.properties\353Q\223\5\0\0\0\0\1\0\0"..., 38, 11139) = 38 <0.000047> [pid 3798984] 12:07:06 pread64(17, "\0$\4rocksdb.block.based.table.ind"..., 664, 10475) = 664 <0.000045> [pid 3798984] 12:07:06 pread64(17, "\0\v\3foo\2M\0\0\0\0\0\0\0\270 \0\v\4foo\2I\0\0\0\0\0\0\275"..., 74, 10401) = 74 <0.000107> [pid 3798983] 12:07:06 pread64(17, "\0\v\200\10foo\2P\0\0\0\0\0\0)U?MSg_)j(roFn($e"..., 2097152, 0) = 11230 <0.000091> [pid 3798983] 12:07:06 pread64(17, "", 2085922, 11230) = 0 <0.000073> [pid 3798983] 12:07:06 pread64(16, "\0\v\200\10foo\2F\0\0\0\0\0\0k[h3%.OPH_^:\\S7T&"..., 2097152, 0) = 11230 <0.000083> [pid 3798983] 12:07:06 pread64(16, "", 2085922, 11230) = 0 <0.000078> [pid 3798983] 12:07:06 pread64(15, "\0\v\200\10foo\2<\0\0\0\0\0\0+qToi_c{*S+4:N(:"..., 2097152, 0) = 11230 <0.000095> [pid 3798983] 12:07:06 pread64(15, "", 2085922, 11230) = 0 <0.000067> [pid 3798983] 12:07:06 pread64(14, "\0\v\200\10foo\0022\0\0\0\0\0\0%hw%OMa\"}9I609Q!B"..., 2097152, 0) = 11230 <0.000111> [pid 3798983] 12:07:06 pread64(14, "", 2085922, 11230) = 0 <0.000093> [pid 3798983] 12:07:06 pread64(13, "\0\v\200\10foo\2(\0\0\0\0\0\0p}Y&mu^DcaSGb2&nP"..., 2097152, 0) = 11230 <0.000128> [pid 3798983] 12:07:06 pread64(13, "", 2085922, 11230) = 0 <0.000076> [pid 3798983] 12:07:06 pread64(12, "\0\v\200\10foo\2\36\0\0\0\0\0\0YIyW#]oSs^6VHfB<`"..., 2097152, 0) = 11230 <0.000092> [pid 3798983] 12:07:06 pread64(12, "", 2085922, 11230) = 0 <0.000073> [pid 3798983] 12:07:06 pread64(11, "\0\v\200\10foo\2\24\0\0\0\0\0\0mfF8Jel/*Zf :-#s("..., 2097152, 0) = 11230 <0.000088> [pid 3798983] 12:07:06 pread64(11, "", 2085922, 11230) = 0 <0.000067> [pid 3798983] 12:07:06 pread64(9, "\0\v\200\10foo\2\n\0\0\0\0\0\0\\X'cjiHX)D,RSj1X!"..., 2097152, 0) = 11230 <0.000115> [pid 3798983] 12:07:06 pread64(9, "", 2085922, 11230) = 0 <0.000073> [pid 3798983] 12:07:06 pread64(8, "\1\315\5 \36\30\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 53, 754) = 53 <0.000098> [pid 3798983] 12:07:06 pread64(8, "\0\22\3rocksdb.properties;\215\5\0\0\0\0\1\0\0\0"..., 37, 717) = 37 <0.000064> [pid 3798983] 12:07:06 pread64(8, "\0$\4rocksdb.block.based.table.ind"..., 658, 59) = 658 <0.000074> [pid 3798983] 12:07:06 pread64(8, "\0\v\2foo\1\0\0\0\0\0\0\0\0\31\0\0\0\0\1\0\0\0\0\212\216\222P", 29, 30) = 29 <0.000064> [pid 3799086] 12:07:06 +++ exited with 0 +++ [pid 3799087] 12:07:06 +++ exited with 0 +++ [pid 3799054] 12:07:06 +++ exited with 0 +++ strace: Process 3799104 attached [pid 3799104] 12:07:06 +++ exited with 0 +++ [ OK ] DBCompactionTest.PartialManualCompaction (757 ms) [----------] 1 test from DBCompactionTest (758 ms total) [----------] Global test environment tear-down [==========] 1 test from 1 test case ran. (759 ms total) [ PASSED ] 1 test. [pid 3798983] 12:07:06 +++ exited with 0 +++ [pid 3798984] 12:07:06 +++ exited with 0 +++ [pid 3798992] 12:07:06 +++ exited with 0 +++ [pid 3798986] 12:07:06 +++ exited with 0 +++ [pid 3798982] 12:07:06 +++ exited with 0 +++ [pid 3798985] 12:07:06 +++ exited with 0 +++ 12:07:06 +++ exited with 0 +++ Differential Revision: D15948422 Pulled By: vjnadimpalli fbshipit-source-id: 9b189d1e8675d290c7784e4b33e5d3b5761d2ac8
5 years ago
} else {
s = Prefetch(file_reader_, offset, n + readahead_size_, for_compaction);
}
Improve direct IO range scan performance with readahead (#3884) Summary: This PR extends the improvements in #3282 to also work when using Direct IO. We see **4.5X performance improvement** in seekrandom benchmark doing long range scans, when using direct reads, on flash. **Description:** This change improves the performance of iterators doing long range scans (e.g. big/full index or table scans in MyRocks) by using readahead and prefetching additional data on each disk IO, and storing in a local buffer. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan. **Implementation Details:** - Used `FilePrefetchBuffer` as the underlying buffer to store the readahead data. `FilePrefetchBuffer` can now take file_reader, readahead_size and max_readahead_size as input to the constructor, and automatically do readahead. - `FilePrefetchBuffer::TryReadFromCache` can now call `FilePrefetchBuffer::Prefetch` if readahead is enabled. - `AlignedBuffer` (which is the underlying store for `FilePrefetchBuffer`) now takes a few additional args in `AlignedBuffer::AllocateNewBuffer` to allow copying data from the old buffer. - Made sure not to re-read partial chunks of data that were already available in the buffer, from device again. - Fixed a couple of cases where `AlignedBuffer::cursize_` was not being properly kept up-to-date. **Constraints:** - Similar to #3282, this gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value). - Since the prefetched data is stored in a temporary buffer allocated on heap, this could increase the memory usage if you have many iterators doing long range scans simultaneously. - Enabled only for user reads, and disabled for compactions. Compaction reads are controlled by the options `use_direct_io_for_flush_and_compaction` and `compaction_readahead_size`, and the current feature takes precautions not to mess with them. **Benchmarks:** I used the same benchmark as used in #3282. Data fill: ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes ``` Do a long range scan: Seekrandom with large number of nexts ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -use_direct_reads -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram ``` ``` Before: seekrandom : 37939.906 micros/op 26 ops/sec; 29.2 MB/s (1636 of 1999 found) With this change: seekrandom : 8527.720 micros/op 117 ops/sec; 129.7 MB/s (6530 of 7999 found) ``` ~4.5X perf improvement. Taken on an average of 3 runs. Closes https://github.com/facebook/rocksdb/pull/3884 Differential Revision: D8082143 Pulled By: sagar0 fbshipit-source-id: 4d7a8561cbac03478663713df4d31ad2620253bb
6 years ago
if (!s.ok()) {
return false;
}
readahead_size_ = std::min(max_readahead_size_, readahead_size_ * 2);
} else {
return false;
}
}
uint64_t offset_in_buffer = offset - buffer_offset_;
*result = Slice(buffer_.BufferStart() + offset_in_buffer, n);
return true;
}
std::unique_ptr<RandomAccessFile> NewReadaheadRandomAccessFile(
Refactor to support file_reader_writer on Windows. Summary. A change https://reviews.facebook.net/differential/diff/224721/ Has attempted to move common functionality out of platform dependent code to a new facility called file_reader_writer. This includes: - perf counters - Buffering - RateLimiting However, the change did not attempt to refactor Windows code. To mitigate, we introduce new quering interfaces such as UseOSBuffer(), GetRequiredBufferAlignment() and ReaderWriterForward() for pure forwarding where required. Introduce WritableFile got a new method Truncate(). This is to communicate to the file as to how much data it has on close. - When space is pre-allocated on Linux it is filled with zeros implicitly, no such thing exist on Windows so we must truncate file on close. - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate. Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has no idea about the file true size. This means that Close() on the wrapper level must always include Truncate() as well as wrapper __dtor should call Close() and against double Close(). Move buffered/unbuffered write logic to the wrapper. Utilize Aligned buffer class. Adjust tests and implement Truncate() where necessary. Come up with reasonable defaults for new virtual interfaces. Forward calls for RandomAccessReadAhead class to avoid double buffering and locking (double locking in unbuffered mode on WIndows).
9 years ago
std::unique_ptr<RandomAccessFile>&& file, size_t readahead_size) {
std::unique_ptr<RandomAccessFile> result(
new ReadaheadRandomAccessFile(std::move(file), readahead_size));
return result;
}
std::unique_ptr<SequentialFile>
SequentialFileReader::NewReadaheadSequentialFile(
std::unique_ptr<SequentialFile>&& file, size_t readahead_size) {
if (file->GetRequiredBufferAlignment() >= readahead_size) {
// Short-circuit and return the original file if readahead_size is
// too small and hence doesn't make sense to be used for prefetching.
return std::move(file);
}
std::unique_ptr<SequentialFile> result(
new ReadaheadSequentialFile(std::move(file), readahead_size));
return result;
}
Status NewWritableFile(Env* env, const std::string& fname,
std::unique_ptr<WritableFile>* result,
const EnvOptions& options) {
Status s = env->NewWritableFile(fname, result, options);
TEST_KILL_RANDOM("NewWritableFile:0", rocksdb_kill_odds * REDUCE_ODDS2);
return s;
}
RocksDB Trace Analyzer (#4091) Summary: A framework of trace analyzing for RocksDB After collecting the trace by using the tool of [PR #3837](https://github.com/facebook/rocksdb/pull/3837). User can use the Trace Analyzer to interpret, analyze, and characterize the collected workload. **Input:** 1. trace file 2. Whole keys space file **Statistics:** 1. Access count of each operation (Get, Put, Delete, SingleDelete, DeleteRange, Merge) in each column family. 2. Key hotness (access count) of each one 3. Key space separation based on given prefix 4. Key size distribution 5. Value size distribution if appliable 6. Top K accessed keys 7. QPS statistics including the average QPS and peak QPS 8. Top K accessed prefix 9. The query correlation analyzing, output the number of X after Y and the corresponding average time intervals **Output:** 1. key access heat map (either in the accessed key space or whole key space) 2. trace sequence file (interpret the raw trace file to line base text file for future use) 3. Time serial (The key space ID and its access time) 4. Key access count distritbution 5. Key size distribution 6. Value size distribution (in each intervals) 7. whole key space separation by the prefix 8. Accessed key space separation by the prefix 9. QPS of each operation and each column family 10. Top K QPS and their accessed prefix range **Test:** 1. Added the unit test of analyzing Get, Put, Delete, SingleDelete, DeleteRange, Merge 2. Generated the trace and analyze the trace **Implemented but not tested (due to the limitation of trace_replay):** 1. Analyzing Iterator, supporting Seek() and SeekForPrev() analyzing 2. Analyzing the number of Key found by Get **Future Work:** 1. Support execution time analyzing of each requests 2. Support cache hit situation and block read situation of Get Pull Request resolved: https://github.com/facebook/rocksdb/pull/4091 Differential Revision: D9256157 Pulled By: zhichao-cao fbshipit-source-id: f0ceacb7eedbc43a3eee6e85b76087d7832a8fe6
6 years ago
bool ReadOneLine(std::istringstream* iss, SequentialFile* seq_file,
std::string* output, bool* has_data, Status* result) {
const int kBufferSize = 8192;
char buffer[kBufferSize + 1];
Slice input_slice;
std::string line;
bool has_complete_line = false;
while (!has_complete_line) {
if (std::getline(*iss, line)) {
has_complete_line = !iss->eof();
} else {
has_complete_line = false;
}
if (!has_complete_line) {
// if we're not sure whether we have a complete line,
// further read from the file.
if (*has_data) {
*result = seq_file->Read(kBufferSize, &input_slice, buffer);
}
if (input_slice.size() == 0) {
// meaning we have read all the data
*has_data = false;
break;
} else {
iss->str(line + input_slice.ToString());
// reset the internal state of iss so that we can keep reading it.
iss->clear();
*has_data = (input_slice.size() == kBufferSize);
continue;
}
}
}
*output = line;
return *has_data || has_complete_line;
}
} // namespace rocksdb