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607 lines
23 KiB
607 lines
23 KiB
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include "file/random_access_file_reader.h"
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#include <algorithm>
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#include <mutex>
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#include "file/file_util.h"
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#include "monitoring/histogram.h"
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#include "monitoring/iostats_context_imp.h"
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#include "port/port.h"
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#include "table/format.h"
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#include "test_util/sync_point.h"
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#include "util/random.h"
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#include "util/rate_limiter_impl.h"
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namespace ROCKSDB_NAMESPACE {
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const std::array<Histograms, std::size_t(Env::IOActivity::kUnknown)>
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kReadHistograms{{
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FILE_READ_FLUSH_MICROS,
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FILE_READ_COMPACTION_MICROS,
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FILE_READ_DB_OPEN_MICROS,
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}};
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inline void RecordIOStats(Statistics* stats, Temperature file_temperature,
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bool is_last_level, size_t size) {
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IOSTATS_ADD(bytes_read, size);
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// record for last/non-last level
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if (is_last_level) {
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RecordTick(stats, LAST_LEVEL_READ_BYTES, size);
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RecordTick(stats, LAST_LEVEL_READ_COUNT, 1);
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} else {
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RecordTick(stats, NON_LAST_LEVEL_READ_BYTES, size);
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RecordTick(stats, NON_LAST_LEVEL_READ_COUNT, 1);
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}
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// record for temperature file
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if (file_temperature != Temperature::kUnknown) {
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switch (file_temperature) {
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case Temperature::kHot:
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IOSTATS_ADD(file_io_stats_by_temperature.hot_file_bytes_read, size);
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IOSTATS_ADD(file_io_stats_by_temperature.hot_file_read_count, 1);
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RecordTick(stats, HOT_FILE_READ_BYTES, size);
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RecordTick(stats, HOT_FILE_READ_COUNT, 1);
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break;
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case Temperature::kWarm:
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IOSTATS_ADD(file_io_stats_by_temperature.warm_file_bytes_read, size);
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IOSTATS_ADD(file_io_stats_by_temperature.warm_file_read_count, 1);
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RecordTick(stats, WARM_FILE_READ_BYTES, size);
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RecordTick(stats, WARM_FILE_READ_COUNT, 1);
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break;
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case Temperature::kCold:
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IOSTATS_ADD(file_io_stats_by_temperature.cold_file_bytes_read, size);
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IOSTATS_ADD(file_io_stats_by_temperature.cold_file_read_count, 1);
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RecordTick(stats, COLD_FILE_READ_BYTES, size);
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RecordTick(stats, COLD_FILE_READ_COUNT, 1);
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break;
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default:
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break;
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}
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}
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}
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IOStatus RandomAccessFileReader::Create(
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const std::shared_ptr<FileSystem>& fs, const std::string& fname,
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const FileOptions& file_opts,
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std::unique_ptr<RandomAccessFileReader>* reader, IODebugContext* dbg) {
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std::unique_ptr<FSRandomAccessFile> file;
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IOStatus io_s = fs->NewRandomAccessFile(fname, file_opts, &file, dbg);
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if (io_s.ok()) {
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reader->reset(new RandomAccessFileReader(std::move(file), fname));
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}
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return io_s;
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}
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IOStatus RandomAccessFileReader::Read(
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const IOOptions& opts, uint64_t offset, size_t n, Slice* result,
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char* scratch, AlignedBuf* aligned_buf,
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Env::IOPriority rate_limiter_priority) const {
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(void)aligned_buf;
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TEST_SYNC_POINT_CALLBACK("RandomAccessFileReader::Read", nullptr);
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// To be paranoid: modify scratch a little bit, so in case underlying
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// FileSystem doesn't fill the buffer but return success and `scratch` returns
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// contains a previous block, returned value will not pass checksum.
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if (n > 0 && scratch != nullptr) {
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// This byte might not change anything for direct I/O case, but it's OK.
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scratch[0]++;
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}
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IOStatus io_s;
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uint64_t elapsed = 0;
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size_t alignment = file_->GetRequiredBufferAlignment();
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bool is_aligned = false;
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if (scratch != nullptr) {
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// Check if offset, length and buffer are aligned.
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is_aligned = (offset & (alignment - 1)) == 0 &&
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(n & (alignment - 1)) == 0 &&
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(uintptr_t(scratch) & (alignment - 1)) == 0;
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}
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{
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StopWatch sw(clock_, stats_, hist_type_,
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(opts.io_activity != Env::IOActivity::kUnknown)
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? kReadHistograms[(std::size_t)(opts.io_activity)]
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: Histograms::HISTOGRAM_ENUM_MAX,
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(stats_ != nullptr) ? &elapsed : nullptr, true /*overwrite*/,
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true /*delay_enabled*/);
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auto prev_perf_level = GetPerfLevel();
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IOSTATS_TIMER_GUARD(read_nanos);
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if (use_direct_io() && is_aligned == false) {
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size_t aligned_offset =
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TruncateToPageBoundary(alignment, static_cast<size_t>(offset));
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size_t offset_advance = static_cast<size_t>(offset) - aligned_offset;
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size_t read_size =
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Roundup(static_cast<size_t>(offset + n), alignment) - aligned_offset;
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AlignedBuffer buf;
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buf.Alignment(alignment);
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buf.AllocateNewBuffer(read_size);
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while (buf.CurrentSize() < read_size) {
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size_t allowed;
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if (rate_limiter_priority != Env::IO_TOTAL &&
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rate_limiter_ != nullptr) {
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allowed = rate_limiter_->RequestToken(
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buf.Capacity() - buf.CurrentSize(), buf.Alignment(),
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rate_limiter_priority, stats_, RateLimiter::OpType::kRead);
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} else {
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assert(buf.CurrentSize() == 0);
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allowed = read_size;
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}
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Slice tmp;
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FileOperationInfo::StartTimePoint start_ts;
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uint64_t orig_offset = 0;
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if (ShouldNotifyListeners()) {
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start_ts = FileOperationInfo::StartNow();
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orig_offset = aligned_offset + buf.CurrentSize();
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}
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{
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IOSTATS_CPU_TIMER_GUARD(cpu_read_nanos, clock_);
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// Only user reads are expected to specify a timeout. And user reads
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// are not subjected to rate_limiter and should go through only
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// one iteration of this loop, so we don't need to check and adjust
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// the opts.timeout before calling file_->Read
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assert(!opts.timeout.count() || allowed == read_size);
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io_s = file_->Read(aligned_offset + buf.CurrentSize(), allowed, opts,
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&tmp, buf.Destination(), nullptr);
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}
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if (ShouldNotifyListeners()) {
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auto finish_ts = FileOperationInfo::FinishNow();
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NotifyOnFileReadFinish(orig_offset, tmp.size(), start_ts, finish_ts,
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io_s);
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if (!io_s.ok()) {
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NotifyOnIOError(io_s, FileOperationType::kRead, file_name(),
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tmp.size(), orig_offset);
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}
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}
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buf.Size(buf.CurrentSize() + tmp.size());
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if (!io_s.ok() || tmp.size() < allowed) {
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break;
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}
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}
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size_t res_len = 0;
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if (io_s.ok() && offset_advance < buf.CurrentSize()) {
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res_len = std::min(buf.CurrentSize() - offset_advance, n);
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if (aligned_buf == nullptr) {
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buf.Read(scratch, offset_advance, res_len);
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} else {
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scratch = buf.BufferStart() + offset_advance;
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aligned_buf->reset(buf.Release());
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}
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}
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*result = Slice(scratch, res_len);
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} else {
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size_t pos = 0;
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const char* res_scratch = nullptr;
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while (pos < n) {
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size_t allowed;
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if (rate_limiter_priority != Env::IO_TOTAL &&
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rate_limiter_ != nullptr) {
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if (rate_limiter_->IsRateLimited(RateLimiter::OpType::kRead)) {
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sw.DelayStart();
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}
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allowed = rate_limiter_->RequestToken(
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n - pos, (use_direct_io() ? alignment : 0), rate_limiter_priority,
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stats_, RateLimiter::OpType::kRead);
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if (rate_limiter_->IsRateLimited(RateLimiter::OpType::kRead)) {
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sw.DelayStop();
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}
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} else {
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allowed = n;
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}
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Slice tmp_result;
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FileOperationInfo::StartTimePoint start_ts;
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if (ShouldNotifyListeners()) {
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start_ts = FileOperationInfo::StartNow();
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}
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{
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IOSTATS_CPU_TIMER_GUARD(cpu_read_nanos, clock_);
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// Only user reads are expected to specify a timeout. And user reads
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// are not subjected to rate_limiter and should go through only
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// one iteration of this loop, so we don't need to check and adjust
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// the opts.timeout before calling file_->Read
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assert(!opts.timeout.count() || allowed == n);
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io_s = file_->Read(offset + pos, allowed, opts, &tmp_result,
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scratch + pos, nullptr);
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}
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if (ShouldNotifyListeners()) {
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auto finish_ts = FileOperationInfo::FinishNow();
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NotifyOnFileReadFinish(offset + pos, tmp_result.size(), start_ts,
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finish_ts, io_s);
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if (!io_s.ok()) {
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NotifyOnIOError(io_s, FileOperationType::kRead, file_name(),
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tmp_result.size(), offset + pos);
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}
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}
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if (res_scratch == nullptr) {
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// we can't simply use `scratch` because reads of mmap'd files return
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// data in a different buffer.
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res_scratch = tmp_result.data();
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} else {
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// make sure chunks are inserted contiguously into `res_scratch`.
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assert(tmp_result.data() == res_scratch + pos);
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}
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pos += tmp_result.size();
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if (!io_s.ok() || tmp_result.size() < allowed) {
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break;
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}
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}
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*result = Slice(res_scratch, io_s.ok() ? pos : 0);
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}
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RecordIOStats(stats_, file_temperature_, is_last_level_, result->size());
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SetPerfLevel(prev_perf_level);
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}
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if (stats_ != nullptr && file_read_hist_ != nullptr) {
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file_read_hist_->Add(elapsed);
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}
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return io_s;
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}
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size_t End(const FSReadRequest& r) {
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return static_cast<size_t>(r.offset) + r.len;
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}
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FSReadRequest Align(const FSReadRequest& r, size_t alignment) {
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FSReadRequest req;
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req.offset = static_cast<uint64_t>(
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TruncateToPageBoundary(alignment, static_cast<size_t>(r.offset)));
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req.len = Roundup(End(r), alignment) - req.offset;
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req.scratch = nullptr;
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return req;
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}
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bool TryMerge(FSReadRequest* dest, const FSReadRequest& src) {
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size_t dest_offset = static_cast<size_t>(dest->offset);
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size_t src_offset = static_cast<size_t>(src.offset);
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size_t dest_end = End(*dest);
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size_t src_end = End(src);
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if (std::max(dest_offset, src_offset) > std::min(dest_end, src_end)) {
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return false;
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}
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dest->offset = static_cast<uint64_t>(std::min(dest_offset, src_offset));
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dest->len = std::max(dest_end, src_end) - dest->offset;
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return true;
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}
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IOStatus RandomAccessFileReader::MultiRead(
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const IOOptions& opts, FSReadRequest* read_reqs, size_t num_reqs,
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AlignedBuf* aligned_buf, Env::IOPriority rate_limiter_priority) const {
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(void)aligned_buf; // suppress warning of unused variable in LITE mode
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assert(num_reqs > 0);
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#ifndef NDEBUG
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for (size_t i = 0; i < num_reqs - 1; ++i) {
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assert(read_reqs[i].offset <= read_reqs[i + 1].offset);
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}
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#endif // !NDEBUG
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// To be paranoid modify scratch a little bit, so in case underlying
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// FileSystem doesn't fill the buffer but return success and `scratch` returns
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// contains a previous block, returned value will not pass checksum.
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// This byte might not change anything for direct I/O case, but it's OK.
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for (size_t i = 0; i < num_reqs; i++) {
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FSReadRequest& r = read_reqs[i];
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if (r.len > 0 && r.scratch != nullptr) {
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r.scratch[0]++;
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}
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}
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IOStatus io_s;
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uint64_t elapsed = 0;
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{
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StopWatch sw(clock_, stats_, hist_type_,
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(opts.io_activity != Env::IOActivity::kUnknown)
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? kReadHistograms[(std::size_t)(opts.io_activity)]
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: Histograms::HISTOGRAM_ENUM_MAX,
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(stats_ != nullptr) ? &elapsed : nullptr, true /*overwrite*/,
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true /*delay_enabled*/);
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auto prev_perf_level = GetPerfLevel();
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IOSTATS_TIMER_GUARD(read_nanos);
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FSReadRequest* fs_reqs = read_reqs;
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size_t num_fs_reqs = num_reqs;
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std::vector<FSReadRequest> aligned_reqs;
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if (use_direct_io()) {
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// num_reqs is the max possible size,
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// this can reduce std::vecector's internal resize operations.
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aligned_reqs.reserve(num_reqs);
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// Align and merge the read requests.
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size_t alignment = file_->GetRequiredBufferAlignment();
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for (size_t i = 0; i < num_reqs; i++) {
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FSReadRequest r = Align(read_reqs[i], alignment);
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if (i == 0) {
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// head
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aligned_reqs.push_back(std::move(r));
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} else if (!TryMerge(&aligned_reqs.back(), r)) {
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// head + n
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aligned_reqs.push_back(std::move(r));
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} else {
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// unused
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r.status.PermitUncheckedError();
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}
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}
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TEST_SYNC_POINT_CALLBACK("RandomAccessFileReader::MultiRead:AlignedReqs",
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&aligned_reqs);
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// Allocate aligned buffer and let scratch buffers point to it.
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size_t total_len = 0;
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for (const auto& r : aligned_reqs) {
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total_len += r.len;
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}
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AlignedBuffer buf;
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buf.Alignment(alignment);
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buf.AllocateNewBuffer(total_len);
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char* scratch = buf.BufferStart();
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for (auto& r : aligned_reqs) {
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r.scratch = scratch;
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scratch += r.len;
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}
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aligned_buf->reset(buf.Release());
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fs_reqs = aligned_reqs.data();
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num_fs_reqs = aligned_reqs.size();
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}
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FileOperationInfo::StartTimePoint start_ts;
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if (ShouldNotifyListeners()) {
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start_ts = FileOperationInfo::StartNow();
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}
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{
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IOSTATS_CPU_TIMER_GUARD(cpu_read_nanos, clock_);
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if (rate_limiter_priority != Env::IO_TOTAL && rate_limiter_ != nullptr) {
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// TODO: ideally we should call `RateLimiter::RequestToken()` for
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// allowed bytes to multi-read and then consume those bytes by
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// satisfying as many requests in `MultiRead()` as possible, instead of
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// what we do here, which can cause burst when the
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// `total_multi_read_size` is big.
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size_t total_multi_read_size = 0;
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assert(fs_reqs != nullptr);
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for (size_t i = 0; i < num_fs_reqs; ++i) {
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FSReadRequest& req = fs_reqs[i];
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total_multi_read_size += req.len;
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}
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size_t remaining_bytes = total_multi_read_size;
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size_t request_bytes = 0;
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while (remaining_bytes > 0) {
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request_bytes = std::min(
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static_cast<size_t>(rate_limiter_->GetSingleBurstBytes()),
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remaining_bytes);
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rate_limiter_->Request(request_bytes, rate_limiter_priority,
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nullptr /* stats */,
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RateLimiter::OpType::kRead);
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remaining_bytes -= request_bytes;
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}
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}
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io_s = file_->MultiRead(fs_reqs, num_fs_reqs, opts, nullptr);
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RecordInHistogram(stats_, MULTIGET_IO_BATCH_SIZE, num_fs_reqs);
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}
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if (use_direct_io()) {
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// Populate results in the unaligned read requests.
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size_t aligned_i = 0;
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for (size_t i = 0; i < num_reqs; i++) {
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auto& r = read_reqs[i];
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if (static_cast<size_t>(r.offset) > End(aligned_reqs[aligned_i])) {
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aligned_i++;
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}
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const auto& fs_r = fs_reqs[aligned_i];
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r.status = fs_r.status;
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if (r.status.ok()) {
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uint64_t offset = r.offset - fs_r.offset;
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if (fs_r.result.size() <= offset) {
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// No byte in the read range is returned.
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r.result = Slice();
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} else {
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size_t len = std::min(
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r.len, static_cast<size_t>(fs_r.result.size() - offset));
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r.result = Slice(fs_r.scratch + offset, len);
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}
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} else {
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r.result = Slice();
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}
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}
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}
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for (size_t i = 0; i < num_reqs; ++i) {
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if (ShouldNotifyListeners()) {
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auto finish_ts = FileOperationInfo::FinishNow();
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NotifyOnFileReadFinish(read_reqs[i].offset, read_reqs[i].result.size(),
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start_ts, finish_ts, read_reqs[i].status);
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}
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if (!read_reqs[i].status.ok()) {
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NotifyOnIOError(read_reqs[i].status, FileOperationType::kRead,
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file_name(), read_reqs[i].result.size(),
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read_reqs[i].offset);
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}
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RecordIOStats(stats_, file_temperature_, is_last_level_,
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read_reqs[i].result.size());
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}
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SetPerfLevel(prev_perf_level);
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}
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if (stats_ != nullptr && file_read_hist_ != nullptr) {
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file_read_hist_->Add(elapsed);
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}
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return io_s;
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}
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IOStatus RandomAccessFileReader::PrepareIOOptions(const ReadOptions& ro,
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IOOptions& opts) const {
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if (clock_ != nullptr) {
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return PrepareIOFromReadOptions(ro, clock_, opts);
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} else {
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return PrepareIOFromReadOptions(ro, SystemClock::Default().get(), opts);
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}
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}
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IOStatus RandomAccessFileReader::ReadAsync(
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FSReadRequest& req, const IOOptions& opts,
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std::function<void(const FSReadRequest&, void*)> cb, void* cb_arg,
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void** io_handle, IOHandleDeleter* del_fn, AlignedBuf* aligned_buf) {
|
|
IOStatus s;
|
|
// Create a callback and populate info.
|
|
auto read_async_callback =
|
|
std::bind(&RandomAccessFileReader::ReadAsyncCallback, this,
|
|
std::placeholders::_1, std::placeholders::_2);
|
|
ReadAsyncInfo* read_async_info =
|
|
new ReadAsyncInfo(cb, cb_arg, clock_->NowMicros());
|
|
|
|
if (ShouldNotifyListeners()) {
|
|
read_async_info->fs_start_ts_ = FileOperationInfo::StartNow();
|
|
}
|
|
|
|
size_t alignment = file_->GetRequiredBufferAlignment();
|
|
bool is_aligned = (req.offset & (alignment - 1)) == 0 &&
|
|
(req.len & (alignment - 1)) == 0 &&
|
|
(uintptr_t(req.scratch) & (alignment - 1)) == 0;
|
|
read_async_info->is_aligned_ = is_aligned;
|
|
|
|
uint64_t elapsed = 0;
|
|
if (use_direct_io() && is_aligned == false) {
|
|
FSReadRequest aligned_req = Align(req, alignment);
|
|
aligned_req.status.PermitUncheckedError();
|
|
|
|
// Allocate aligned buffer.
|
|
read_async_info->buf_.Alignment(alignment);
|
|
read_async_info->buf_.AllocateNewBuffer(aligned_req.len);
|
|
|
|
// Set rem fields in aligned FSReadRequest.
|
|
aligned_req.scratch = read_async_info->buf_.BufferStart();
|
|
|
|
// Set user provided fields to populate back in callback.
|
|
read_async_info->user_scratch_ = req.scratch;
|
|
read_async_info->user_aligned_buf_ = aligned_buf;
|
|
read_async_info->user_len_ = req.len;
|
|
read_async_info->user_offset_ = req.offset;
|
|
read_async_info->user_result_ = req.result;
|
|
|
|
assert(read_async_info->buf_.CurrentSize() == 0);
|
|
|
|
StopWatch sw(clock_, nullptr /*stats*/,
|
|
Histograms::HISTOGRAM_ENUM_MAX /*hist_type*/,
|
|
Histograms::HISTOGRAM_ENUM_MAX, &elapsed, true /*overwrite*/,
|
|
true /*delay_enabled*/);
|
|
s = file_->ReadAsync(aligned_req, opts, read_async_callback,
|
|
read_async_info, io_handle, del_fn, nullptr /*dbg*/);
|
|
} else {
|
|
StopWatch sw(clock_, nullptr /*stats*/,
|
|
Histograms::HISTOGRAM_ENUM_MAX /*hist_type*/,
|
|
Histograms::HISTOGRAM_ENUM_MAX, &elapsed, true /*overwrite*/,
|
|
true /*delay_enabled*/);
|
|
s = file_->ReadAsync(req, opts, read_async_callback, read_async_info,
|
|
io_handle, del_fn, nullptr /*dbg*/);
|
|
}
|
|
RecordTick(stats_, READ_ASYNC_MICROS, elapsed);
|
|
|
|
// Suppress false positive clang analyzer warnings.
|
|
// Memory is not released if file_->ReadAsync returns !s.ok(), because
|
|
// ReadAsyncCallback is never called in that case. If ReadAsyncCallback is
|
|
// called then ReadAsync should always return IOStatus::OK().
|
|
#ifndef __clang_analyzer__
|
|
if (!s.ok()) {
|
|
delete read_async_info;
|
|
}
|
|
#endif // __clang_analyzer__
|
|
|
|
return s;
|
|
}
|
|
|
|
void RandomAccessFileReader::ReadAsyncCallback(const FSReadRequest& req,
|
|
void* cb_arg) {
|
|
ReadAsyncInfo* read_async_info = static_cast<ReadAsyncInfo*>(cb_arg);
|
|
assert(read_async_info);
|
|
assert(read_async_info->cb_);
|
|
|
|
if (use_direct_io() && read_async_info->is_aligned_ == false) {
|
|
// Create FSReadRequest with user provided fields.
|
|
FSReadRequest user_req;
|
|
user_req.scratch = read_async_info->user_scratch_;
|
|
user_req.offset = read_async_info->user_offset_;
|
|
user_req.len = read_async_info->user_len_;
|
|
|
|
// Update results in user_req.
|
|
user_req.result = req.result;
|
|
user_req.status = req.status;
|
|
|
|
read_async_info->buf_.Size(read_async_info->buf_.CurrentSize() +
|
|
req.result.size());
|
|
|
|
size_t offset_advance_len = static_cast<size_t>(
|
|
/*offset_passed_by_user=*/read_async_info->user_offset_ -
|
|
/*aligned_offset=*/req.offset);
|
|
|
|
size_t res_len = 0;
|
|
if (req.status.ok() &&
|
|
offset_advance_len < read_async_info->buf_.CurrentSize()) {
|
|
res_len =
|
|
std::min(read_async_info->buf_.CurrentSize() - offset_advance_len,
|
|
read_async_info->user_len_);
|
|
if (read_async_info->user_aligned_buf_ == nullptr) {
|
|
// Copy the data into user's scratch.
|
|
// Clang analyzer assumes that it will take use_direct_io() == false in
|
|
// ReadAsync and use_direct_io() == true in Callback which cannot be true.
|
|
#ifndef __clang_analyzer__
|
|
read_async_info->buf_.Read(user_req.scratch, offset_advance_len,
|
|
res_len);
|
|
#endif // __clang_analyzer__
|
|
} else {
|
|
// Set aligned_buf provided by user without additional copy.
|
|
user_req.scratch =
|
|
read_async_info->buf_.BufferStart() + offset_advance_len;
|
|
read_async_info->user_aligned_buf_->reset(
|
|
read_async_info->buf_.Release());
|
|
}
|
|
user_req.result = Slice(user_req.scratch, res_len);
|
|
} else {
|
|
// Either req.status is not ok or data was not read.
|
|
user_req.result = Slice();
|
|
}
|
|
read_async_info->cb_(user_req, read_async_info->cb_arg_);
|
|
} else {
|
|
read_async_info->cb_(req, read_async_info->cb_arg_);
|
|
}
|
|
|
|
// Update stats and notify listeners.
|
|
if (stats_ != nullptr && file_read_hist_ != nullptr) {
|
|
// elapsed doesn't take into account delay and overwrite as StopWatch does
|
|
// in Read.
|
|
uint64_t elapsed = clock_->NowMicros() - read_async_info->start_time_;
|
|
file_read_hist_->Add(elapsed);
|
|
}
|
|
if (req.status.ok()) {
|
|
RecordInHistogram(stats_, ASYNC_READ_BYTES, req.result.size());
|
|
} else if (!req.status.IsAborted()) {
|
|
RecordTick(stats_, ASYNC_READ_ERROR_COUNT, 1);
|
|
}
|
|
if (ShouldNotifyListeners()) {
|
|
auto finish_ts = FileOperationInfo::FinishNow();
|
|
NotifyOnFileReadFinish(req.offset, req.result.size(),
|
|
read_async_info->fs_start_ts_, finish_ts,
|
|
req.status);
|
|
}
|
|
if (!req.status.ok()) {
|
|
NotifyOnIOError(req.status, FileOperationType::kRead, file_name(),
|
|
req.result.size(), req.offset);
|
|
}
|
|
RecordIOStats(stats_, file_temperature_, is_last_level_, req.result.size());
|
|
delete read_async_info;
|
|
}
|
|
} // namespace ROCKSDB_NAMESPACE
|
|
|