// Copyright (c) Facebook, Inc. and its affiliates. 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).
#include "util/stop_watch.h"
#ifndef ROCKSDB_LITE
#include "tools/simulated_hybrid_file_system.h"
#include <algorithm>
#include <sstream>
#include <string>
#include "rocksdb/rate_limiter.h"
namespace ROCKSDB_NAMESPACE {
const int64_t kUsPerSec = 1000000;
const int64_t kDummyBytesPerUs = 1024;
namespace {
// From bytes to read/write, calculate service time needed by an HDD.
// This is used to simulate latency from HDD.
int CalculateServeTimeUs(size_t bytes) {
return 12200 + static_cast<int>(static_cast<double>(bytes) * 0.005215);
}
// There is a bug in rater limiter that would crash with small requests
// Hack to get it around.
void RateLimiterRequest(RateLimiter* rater_limiter, int64_t amount) {
int64_t left = amount * kDummyBytesPerUs;
const int64_t kMaxToRequest = kDummyBytesPerUs * kUsPerSec / 1024;
while (left > 0) {
int64_t to_request = std::min(kMaxToRequest, left);
rater_limiter->Request(to_request, Env::IOPriority::IO_LOW, nullptr);
left -= to_request;
}
}
} // namespace
// The metadata file format: each line is a full filename of a file which is
// warm
SimulatedHybridFileSystem::SimulatedHybridFileSystem(
const std::shared_ptr<FileSystem>& base,
const std::string& metadata_file_name, int throughput_multiplier,
bool is_full_fs_warm)
: FileSystemWrapper(base),
// Limit to 100 requests per second.
rate_limiter_(NewGenericRateLimiter(
int64_t{throughput_multiplier} * kDummyBytesPerUs *
kUsPerSec /* rate_bytes_per_sec */,
1000 /* refill_period_us */)),
metadata_file_name_(metadata_file_name),
name_("SimulatedHybridFileSystem: " + std::string(target()->Name())),
is_full_fs_warm_(is_full_fs_warm) {
IOStatus s = base->FileExists(metadata_file_name, IOOptions(), nullptr);
if (s.IsNotFound()) {
return;
}
std::string metadata;
s = ReadFileToString(base.get(), metadata_file_name, &metadata);
if (!s.ok()) {
fprintf(stderr, "Error reading from file %s: %s",
metadata_file_name.c_str(), s.ToString().c_str());
// Exit rather than assert as this file system is built to run with
// benchmarks, which usually run on release mode.
std::exit(1);
}
std::istringstream input;
input.str(metadata);
std::string line;
while (std::getline(input, line)) {
fprintf(stderr, "Warm file %s\n", line.c_str());
warm_file_set_.insert(line);
}
}
// Need to write out the metadata file to file. See comment of
// SimulatedHybridFileSystem::SimulatedHybridFileSystem() for format of the
// file.
SimulatedHybridFileSystem::~SimulatedHybridFileSystem() {
if (metadata_file_name_.empty()) {
return;
}
std::string metadata;
for (const auto& f : warm_file_set_) {
metadata += f;
metadata += "\n";
}
IOStatus s = WriteStringToFile(target(), metadata, metadata_file_name_, true);
if (!s.ok()) {
fprintf(stderr, "Error writing to file %s: %s", metadata_file_name_.c_str(),
s.ToString().c_str());
}
}
IOStatus SimulatedHybridFileSystem::NewRandomAccessFile(
const std::string& fname, const FileOptions& file_opts,
std::unique_ptr<FSRandomAccessFile>* result, IODebugContext* dbg) {
Temperature temperature = Temperature::kUnknown;
if (is_full_fs_warm_) {
temperature = Temperature::kWarm;
} else {
const std::lock_guard<std::mutex> lock(mutex_);
if (warm_file_set_.find(fname) != warm_file_set_.end()) {
temperature = Temperature::kWarm;
}
assert(temperature == file_opts.temperature);
}
IOStatus s = target()->NewRandomAccessFile(fname, file_opts, result, dbg);
result->reset(
new SimulatedHybridRaf(std::move(*result), rate_limiter_, temperature));
return s;
}
IOStatus SimulatedHybridFileSystem::NewWritableFile(
const std::string& fname, const FileOptions& file_opts,
std::unique_ptr<FSWritableFile>* result, IODebugContext* dbg) {
if (file_opts.temperature == Temperature::kWarm) {
const std::lock_guard<std::mutex> lock(mutex_);
warm_file_set_.insert(fname);
}
IOStatus s = target()->NewWritableFile(fname, file_opts, result, dbg);
if (file_opts.temperature == Temperature::kWarm || is_full_fs_warm_) {
result->reset(new SimulatedWritableFile(std::move(*result), rate_limiter_));
}
return s;
}
IOStatus SimulatedHybridFileSystem::DeleteFile(const std::string& fname,
const IOOptions& options,
IODebugContext* dbg) {
{
const std::lock_guard<std::mutex> lock(mutex_);
warm_file_set_.erase(fname);
}
return target()->DeleteFile(fname, options, dbg);
}
IOStatus SimulatedHybridRaf::Read(uint64_t offset, size_t n,
const IOOptions& options, Slice* result,
char* scratch, IODebugContext* dbg) const {
if (temperature_ == Temperature::kWarm) {
SimulateIOWait(n);
}
return target()->Read(offset, n, options, result, scratch, dbg);
}
IOStatus SimulatedHybridRaf::MultiRead(FSReadRequest* reqs, size_t num_reqs,
const IOOptions& options,
IODebugContext* dbg) {
if (temperature_ == Temperature::kWarm) {
for (size_t i = 0; i < num_reqs; i++) {
SimulateIOWait(reqs[i].len);
}
}
return target()->MultiRead(reqs, num_reqs, options, dbg);
}
IOStatus SimulatedHybridRaf::Prefetch(uint64_t offset, size_t n,
const IOOptions& options,
IODebugContext* dbg) {
if (temperature_ == Temperature::kWarm) {
SimulateIOWait(n);
}
return target()->Prefetch(offset, n, options, dbg);
}
void SimulatedHybridRaf::SimulateIOWait(int64_t bytes) const {
int serve_time = CalculateServeTimeUs(bytes);
{
StopWatchNano stop_watch(Env::Default()->GetSystemClock().get(),
/*auto_start=*/true);
RateLimiterRequest(rate_limiter_.get(), serve_time);
int time_passed_us = static_cast<int>(stop_watch.ElapsedNanos() / 1000);
if (time_passed_us < serve_time) {
Env::Default()->SleepForMicroseconds(serve_time - time_passed_us);
}
}
}
void SimulatedWritableFile::SimulateIOWait(int64_t bytes) const {
int serve_time = CalculateServeTimeUs(bytes);
Env::Default()->SleepForMicroseconds(serve_time);
RateLimiterRequest(rate_limiter_.get(), serve_time);
}
IOStatus SimulatedWritableFile::Append(const Slice& data, const IOOptions& ioo,
IODebugContext* idc) {
if (use_direct_io()) {
SimulateIOWait(data.size());
} else {
unsynced_bytes += data.size();
}
return target()->Append(data, ioo, idc);
}
IOStatus SimulatedWritableFile::Append(
const Slice& data, const IOOptions& options,
const DataVerificationInfo& verification_info, IODebugContext* dbg) {
if (use_direct_io()) {
SimulateIOWait(data.size());
} else {
unsynced_bytes += data.size();
}
return target()->Append(data, options, verification_info, dbg);
}
IOStatus SimulatedWritableFile::PositionedAppend(const Slice& data,
uint64_t offset,
const IOOptions& options,
IODebugContext* dbg) {
if (use_direct_io()) {
SimulateIOWait(data.size());
} else {
// This might be overcalculated, but it's probably OK.
unsynced_bytes += data.size();
}
return target()->PositionedAppend(data, offset, options, dbg);
}
IOStatus SimulatedWritableFile::PositionedAppend(
const Slice& data, uint64_t offset, const IOOptions& options,
const DataVerificationInfo& verification_info, IODebugContext* dbg) {
if (use_direct_io()) {
SimulateIOWait(data.size());
} else {
// This might be overcalculated, but it's probably OK.
unsynced_bytes += data.size();
}
return target()->PositionedAppend(data, offset, options, verification_info,
dbg);
}
IOStatus SimulatedWritableFile::Sync(const IOOptions& options,
IODebugContext* dbg) {
if (unsynced_bytes > 0) {
SimulateIOWait(unsynced_bytes);
unsynced_bytes = 0;
}
return target()->Sync(options, dbg);
}
} // namespace ROCKSDB_NAMESPACE
#endif // ROCKSDB_LITE