rocksdb/file/writable_file_writer.cc
2022-05-16 11:59:03 -07:00

919 lines
32 KiB
C++

// 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 "file/writable_file_writer.h"
#include <algorithm>
#include <mutex>
#include "db/version_edit.h"
#include "monitoring/histogram.h"
#include "monitoring/iostats_context_imp.h"
#include "port/port.h"
#include "rocksdb/system_clock.h"
#include "test_util/sync_point.h"
#include "util/crc32c.h"
#include "util/random.h"
#include "util/rate_limiter.h"
namespace ROCKSDB_NAMESPACE {
IOStatus WritableFileWriter::Create(const std::shared_ptr<FileSystem>& fs,
const std::string& fname,
const FileOptions& file_opts,
std::unique_ptr<WritableFileWriter>* writer,
IODebugContext* dbg) {
if (file_opts.use_direct_writes &&
0 == file_opts.writable_file_max_buffer_size) {
return IOStatus::InvalidArgument(
"Direct write requires writable_file_max_buffer_size > 0");
}
std::unique_ptr<FSWritableFile> file;
IOStatus io_s = fs->NewWritableFile(fname, file_opts, &file, dbg);
if (io_s.ok()) {
writer->reset(new WritableFileWriter(std::move(file), fname, file_opts));
}
return io_s;
}
IOStatus WritableFileWriter::Append(const Slice& data, uint32_t crc32c_checksum,
Env::IOPriority op_rate_limiter_priority) {
const char* src = data.data();
size_t left = data.size();
IOStatus s;
pending_sync_ = true;
TEST_KILL_RANDOM_WITH_WEIGHT("WritableFileWriter::Append:0", REDUCE_ODDS2);
// Calculate the checksum of appended data
UpdateFileChecksum(data);
{
IOOptions io_options;
WritableFileWriter::DecideRateLimiterPriority(
writable_file_->GetIOPriority(), op_rate_limiter_priority, io_options);
IOSTATS_TIMER_GUARD(prepare_write_nanos);
TEST_SYNC_POINT("WritableFileWriter::Append:BeforePrepareWrite");
writable_file_->PrepareWrite(static_cast<size_t>(GetFileSize()), left,
io_options, nullptr);
}
// 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) {
s = Flush(op_rate_limiter_priority);
if (!s.ok()) {
return s;
}
}
assert(buf_.CurrentSize() == 0);
}
if (perform_data_verification_ && buffered_data_with_checksum_ &&
crc32c_checksum != 0) {
// Since we want to use the checksum of the input data, we cannot break it
// into several pieces. We will only write them in the buffer when buffer
// size is enough. Otherwise, we will directly write it down.
if (use_direct_io() || (buf_.Capacity() - buf_.CurrentSize()) >= left) {
if ((buf_.Capacity() - buf_.CurrentSize()) >= left) {
size_t appended = buf_.Append(src, left);
if (appended != left) {
s = IOStatus::Corruption("Write buffer append failure");
}
buffered_data_crc32c_checksum_ = crc32c::Crc32cCombine(
buffered_data_crc32c_checksum_, crc32c_checksum, appended);
} else {
while (left > 0) {
size_t appended = buf_.Append(src, left);
buffered_data_crc32c_checksum_ =
crc32c::Extend(buffered_data_crc32c_checksum_, src, appended);
left -= appended;
src += appended;
if (left > 0) {
s = Flush(op_rate_limiter_priority);
if (!s.ok()) {
break;
}
}
}
}
} else {
assert(buf_.CurrentSize() == 0);
buffered_data_crc32c_checksum_ = crc32c_checksum;
s = WriteBufferedWithChecksum(src, left, op_rate_limiter_priority);
}
} else {
// In this case, either we do not need to do the data verification or
// caller does not provide the checksum of the data (crc32c_checksum = 0).
//
// We never write directly to disk with direct I/O on.
// or we simply use it for its original purpose to accumulate many small
// chunks
if (use_direct_io() || (buf_.Capacity() >= left)) {
while (left > 0) {
size_t appended = buf_.Append(src, left);
if (perform_data_verification_ && buffered_data_with_checksum_) {
buffered_data_crc32c_checksum_ =
crc32c::Extend(buffered_data_crc32c_checksum_, src, appended);
}
left -= appended;
src += appended;
if (left > 0) {
s = Flush(op_rate_limiter_priority);
if (!s.ok()) {
break;
}
}
}
} else {
// Writing directly to file bypassing the buffer
assert(buf_.CurrentSize() == 0);
if (perform_data_verification_ && buffered_data_with_checksum_) {
buffered_data_crc32c_checksum_ = crc32c::Value(src, left);
s = WriteBufferedWithChecksum(src, left, op_rate_limiter_priority);
} else {
s = WriteBuffered(src, left, op_rate_limiter_priority);
}
}
}
TEST_KILL_RANDOM("WritableFileWriter::Append:1");
if (s.ok()) {
filesize_ += data.size();
}
return s;
}
IOStatus WritableFileWriter::Pad(const size_t pad_bytes,
Env::IOPriority op_rate_limiter_priority) {
assert(pad_bytes < kDefaultPageSize);
size_t left = pad_bytes;
size_t cap = buf_.Capacity() - buf_.CurrentSize();
size_t pad_start = 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) {
IOStatus s = Flush(op_rate_limiter_priority);
if (!s.ok()) {
return s;
}
}
cap = buf_.Capacity() - buf_.CurrentSize();
}
pending_sync_ = true;
filesize_ += pad_bytes;
if (perform_data_verification_) {
buffered_data_crc32c_checksum_ =
crc32c::Extend(buffered_data_crc32c_checksum_,
buf_.BufferStart() + pad_start, pad_bytes);
}
return IOStatus::OK();
}
IOStatus WritableFileWriter::Close() {
// Do not quit immediately on failure the file MUST be closed
IOStatus s;
// 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_.get() == nullptr) {
return s;
}
s = Flush(); // flush cache to OS
IOStatus interim;
IOOptions io_options;
io_options.rate_limiter_priority = writable_file_->GetIOPriority();
// In direct I/O mode we write whole pages so
// we need to let the file know where data ends.
if (use_direct_io()) {
{
#ifndef ROCKSDB_LITE
FileOperationInfo::StartTimePoint start_ts;
if (ShouldNotifyListeners()) {
start_ts = FileOperationInfo::StartNow();
}
#endif
interim = writable_file_->Truncate(filesize_, io_options, nullptr);
#ifndef ROCKSDB_LITE
if (ShouldNotifyListeners()) {
auto finish_ts = FileOperationInfo::FinishNow();
NotifyOnFileTruncateFinish(start_ts, finish_ts, s);
if (!interim.ok()) {
NotifyOnIOError(interim, FileOperationType::kTruncate, file_name(),
filesize_);
}
}
#endif
}
if (interim.ok()) {
{
#ifndef ROCKSDB_LITE
FileOperationInfo::StartTimePoint start_ts;
if (ShouldNotifyListeners()) {
start_ts = FileOperationInfo::StartNow();
}
#endif
interim = writable_file_->Fsync(io_options, nullptr);
#ifndef ROCKSDB_LITE
if (ShouldNotifyListeners()) {
auto finish_ts = FileOperationInfo::FinishNow();
NotifyOnFileSyncFinish(start_ts, finish_ts, s,
FileOperationType::kFsync);
if (!interim.ok()) {
NotifyOnIOError(interim, FileOperationType::kFsync, file_name());
}
}
#endif
}
}
if (!interim.ok() && s.ok()) {
s = interim;
}
}
TEST_KILL_RANDOM("WritableFileWriter::Close:0");
{
#ifndef ROCKSDB_LITE
FileOperationInfo::StartTimePoint start_ts;
if (ShouldNotifyListeners()) {
start_ts = FileOperationInfo::StartNow();
}
#endif
interim = writable_file_->Close(io_options, nullptr);
#ifndef ROCKSDB_LITE
if (ShouldNotifyListeners()) {
auto finish_ts = FileOperationInfo::FinishNow();
NotifyOnFileCloseFinish(start_ts, finish_ts, s);
if (!interim.ok()) {
NotifyOnIOError(interim, FileOperationType::kClose, file_name());
}
}
#endif
}
if (!interim.ok() && s.ok()) {
s = interim;
}
writable_file_.reset();
TEST_KILL_RANDOM("WritableFileWriter::Close:1");
if (s.ok() && checksum_generator_ != nullptr && !checksum_finalized_) {
checksum_generator_->Finalize();
checksum_finalized_ = true;
}
return s;
}
// write out the cached data to the OS cache or storage if direct I/O
// enabled
IOStatus WritableFileWriter::Flush(Env::IOPriority op_rate_limiter_priority) {
IOStatus s;
TEST_KILL_RANDOM_WITH_WEIGHT("WritableFileWriter::Flush:0", REDUCE_ODDS2);
if (buf_.CurrentSize() > 0) {
if (use_direct_io()) {
#ifndef ROCKSDB_LITE
if (pending_sync_) {
if (perform_data_verification_ && buffered_data_with_checksum_) {
s = WriteDirectWithChecksum(op_rate_limiter_priority);
} else {
s = WriteDirect(op_rate_limiter_priority);
}
}
#endif // !ROCKSDB_LITE
} else {
if (perform_data_verification_ && buffered_data_with_checksum_) {
s = WriteBufferedWithChecksum(buf_.BufferStart(), buf_.CurrentSize(),
op_rate_limiter_priority);
} else {
s = WriteBuffered(buf_.BufferStart(), buf_.CurrentSize(),
op_rate_limiter_priority);
}
}
if (!s.ok()) {
return s;
}
}
{
#ifndef ROCKSDB_LITE
FileOperationInfo::StartTimePoint start_ts;
if (ShouldNotifyListeners()) {
start_ts = FileOperationInfo::StartNow();
}
#endif
IOOptions io_options;
WritableFileWriter::DecideRateLimiterPriority(
writable_file_->GetIOPriority(), op_rate_limiter_priority, io_options);
s = writable_file_->Flush(io_options, nullptr);
#ifndef ROCKSDB_LITE
if (ShouldNotifyListeners()) {
auto finish_ts = std::chrono::steady_clock::now();
NotifyOnFileFlushFinish(start_ts, finish_ts, s);
if (!s.ok()) {
NotifyOnIOError(s, FileOperationType::kFlush, file_name());
}
}
#endif
}
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_) {
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_) {
s = RangeSync(last_sync_size_, offset_sync_to - last_sync_size_);
last_sync_size_ = offset_sync_to;
}
}
}
return s;
}
std::string WritableFileWriter::GetFileChecksum() {
if (checksum_generator_ != nullptr) {
assert(checksum_finalized_);
return checksum_generator_->GetChecksum();
} else {
return kUnknownFileChecksum;
}
}
const char* WritableFileWriter::GetFileChecksumFuncName() const {
if (checksum_generator_ != nullptr) {
return checksum_generator_->Name();
} else {
return kUnknownFileChecksumFuncName;
}
}
IOStatus WritableFileWriter::Sync(bool use_fsync) {
IOStatus s = Flush();
if (!s.ok()) {
return s;
}
TEST_KILL_RANDOM("WritableFileWriter::Sync:0");
if (!use_direct_io() && pending_sync_) {
s = SyncInternal(use_fsync);
if (!s.ok()) {
return s;
}
}
TEST_KILL_RANDOM("WritableFileWriter::Sync:1");
pending_sync_ = false;
return IOStatus::OK();
}
IOStatus WritableFileWriter::SyncWithoutFlush(bool use_fsync) {
if (!writable_file_->IsSyncThreadSafe()) {
return IOStatus::NotSupported(
"Can't WritableFileWriter::SyncWithoutFlush() because "
"WritableFile::IsSyncThreadSafe() is false");
}
TEST_SYNC_POINT("WritableFileWriter::SyncWithoutFlush:1");
IOStatus s = SyncInternal(use_fsync);
TEST_SYNC_POINT("WritableFileWriter::SyncWithoutFlush:2");
return s;
}
IOStatus WritableFileWriter::SyncInternal(bool use_fsync) {
IOStatus s;
IOSTATS_TIMER_GUARD(fsync_nanos);
TEST_SYNC_POINT("WritableFileWriter::SyncInternal:0");
auto prev_perf_level = GetPerfLevel();
IOSTATS_CPU_TIMER_GUARD(cpu_write_nanos, clock_);
#ifndef ROCKSDB_LITE
FileOperationInfo::StartTimePoint start_ts;
if (ShouldNotifyListeners()) {
start_ts = FileOperationInfo::StartNow();
}
#endif
IOOptions io_options;
io_options.rate_limiter_priority = writable_file_->GetIOPriority();
if (use_fsync) {
s = writable_file_->Fsync(io_options, nullptr);
} else {
s = writable_file_->Sync(io_options, nullptr);
}
#ifndef ROCKSDB_LITE
if (ShouldNotifyListeners()) {
auto finish_ts = std::chrono::steady_clock::now();
NotifyOnFileSyncFinish(
start_ts, finish_ts, s,
use_fsync ? FileOperationType::kFsync : FileOperationType::kSync);
if (!s.ok()) {
NotifyOnIOError(
s, (use_fsync ? FileOperationType::kFsync : FileOperationType::kSync),
file_name());
}
}
#endif
SetPerfLevel(prev_perf_level);
return s;
}
IOStatus WritableFileWriter::RangeSync(uint64_t offset, uint64_t nbytes) {
IOSTATS_TIMER_GUARD(range_sync_nanos);
TEST_SYNC_POINT("WritableFileWriter::RangeSync:0");
#ifndef ROCKSDB_LITE
FileOperationInfo::StartTimePoint start_ts;
if (ShouldNotifyListeners()) {
start_ts = FileOperationInfo::StartNow();
}
#endif
IOOptions io_options;
io_options.rate_limiter_priority = writable_file_->GetIOPriority();
IOStatus s = writable_file_->RangeSync(offset, nbytes, io_options, nullptr);
#ifndef ROCKSDB_LITE
if (ShouldNotifyListeners()) {
auto finish_ts = std::chrono::steady_clock::now();
NotifyOnFileRangeSyncFinish(offset, nbytes, start_ts, finish_ts, s);
if (!s.ok()) {
NotifyOnIOError(s, FileOperationType::kRangeSync, file_name(), nbytes,
offset);
}
}
#endif
return s;
}
// This method writes to disk the specified data and makes use of the rate
// limiter if available
IOStatus WritableFileWriter::WriteBuffered(
const char* data, size_t size, Env::IOPriority op_rate_limiter_priority) {
IOStatus s;
assert(!use_direct_io());
const char* src = data;
size_t left = size;
DataVerificationInfo v_info;
char checksum_buf[sizeof(uint32_t)];
IOOptions io_options;
Env::IOPriority rate_limiter_priority_used =
WritableFileWriter::DecideRateLimiterPriority(
writable_file_->GetIOPriority(), op_rate_limiter_priority,
io_options);
while (left > 0) {
size_t allowed = left;
if (rate_limiter_ != nullptr &&
rate_limiter_priority_used != Env::IO_TOTAL) {
allowed = rate_limiter_->RequestToken(left, 0 /* alignment */,
rate_limiter_priority_used, stats_,
RateLimiter::OpType::kWrite);
}
{
IOSTATS_TIMER_GUARD(write_nanos);
TEST_SYNC_POINT("WritableFileWriter::Flush:BeforeAppend");
#ifndef ROCKSDB_LITE
FileOperationInfo::StartTimePoint start_ts;
uint64_t old_size = writable_file_->GetFileSize(io_options, nullptr);
if (ShouldNotifyListeners()) {
start_ts = FileOperationInfo::StartNow();
old_size = next_write_offset_;
}
#endif
{
auto prev_perf_level = GetPerfLevel();
IOSTATS_CPU_TIMER_GUARD(cpu_write_nanos, clock_);
if (perform_data_verification_) {
Crc32cHandoffChecksumCalculation(src, allowed, checksum_buf);
v_info.checksum = Slice(checksum_buf, sizeof(uint32_t));
s = writable_file_->Append(Slice(src, allowed), io_options, v_info,
nullptr);
} else {
s = writable_file_->Append(Slice(src, allowed), io_options, nullptr);
}
if (!s.ok()) {
// If writable_file_->Append() failed, then the data may or may not
// exist in the underlying memory buffer, OS page cache, remote file
// system's buffer, etc. If WritableFileWriter keeps the data in
// buf_, then a future Close() or write retry may send the data to
// the underlying file again. If the data does exist in the
// underlying buffer and gets written to the file eventually despite
// returning error, the file may end up with two duplicate pieces of
// data. Therefore, clear the buf_ at the WritableFileWriter layer
// and let caller determine error handling.
buf_.Size(0);
buffered_data_crc32c_checksum_ = 0;
}
SetPerfLevel(prev_perf_level);
}
#ifndef ROCKSDB_LITE
if (ShouldNotifyListeners()) {
auto finish_ts = std::chrono::steady_clock::now();
NotifyOnFileWriteFinish(old_size, allowed, start_ts, finish_ts, s);
if (!s.ok()) {
NotifyOnIOError(s, FileOperationType::kAppend, file_name(), allowed,
old_size);
}
}
#endif
if (!s.ok()) {
return s;
}
}
IOSTATS_ADD(bytes_written, allowed);
TEST_KILL_RANDOM("WritableFileWriter::WriteBuffered:0");
left -= allowed;
src += allowed;
}
buf_.Size(0);
buffered_data_crc32c_checksum_ = 0;
return s;
}
IOStatus WritableFileWriter::WriteBufferedWithChecksum(
const char* data, size_t size, Env::IOPriority op_rate_limiter_priority) {
IOStatus s;
assert(!use_direct_io());
assert(perform_data_verification_ && buffered_data_with_checksum_);
const char* src = data;
size_t left = size;
DataVerificationInfo v_info;
char checksum_buf[sizeof(uint32_t)];
IOOptions io_options;
Env::IOPriority rate_limiter_priority_used =
WritableFileWriter::DecideRateLimiterPriority(
writable_file_->GetIOPriority(), op_rate_limiter_priority,
io_options);
// Check how much is allowed. Here, we loop until the rate limiter allows to
// write the entire buffer.
// TODO: need to be improved since it sort of defeats the purpose of the rate
// limiter
size_t data_size = left;
if (rate_limiter_ != nullptr && rate_limiter_priority_used != Env::IO_TOTAL) {
while (data_size > 0) {
size_t tmp_size;
tmp_size = rate_limiter_->RequestToken(data_size, buf_.Alignment(),
rate_limiter_priority_used, stats_,
RateLimiter::OpType::kWrite);
data_size -= tmp_size;
}
}
{
IOSTATS_TIMER_GUARD(write_nanos);
TEST_SYNC_POINT("WritableFileWriter::Flush:BeforeAppend");
#ifndef ROCKSDB_LITE
FileOperationInfo::StartTimePoint start_ts;
uint64_t old_size = writable_file_->GetFileSize(io_options, nullptr);
if (ShouldNotifyListeners()) {
start_ts = FileOperationInfo::StartNow();
old_size = next_write_offset_;
}
#endif
{
auto prev_perf_level = GetPerfLevel();
IOSTATS_CPU_TIMER_GUARD(cpu_write_nanos, clock_);
EncodeFixed32(checksum_buf, buffered_data_crc32c_checksum_);
v_info.checksum = Slice(checksum_buf, sizeof(uint32_t));
s = writable_file_->Append(Slice(src, left), io_options, v_info, nullptr);
SetPerfLevel(prev_perf_level);
}
#ifndef ROCKSDB_LITE
if (ShouldNotifyListeners()) {
auto finish_ts = std::chrono::steady_clock::now();
NotifyOnFileWriteFinish(old_size, left, start_ts, finish_ts, s);
if (!s.ok()) {
NotifyOnIOError(s, FileOperationType::kAppend, file_name(), left,
old_size);
}
}
#endif
if (!s.ok()) {
// If writable_file_->Append() failed, then the data may or may not
// exist in the underlying memory buffer, OS page cache, remote file
// system's buffer, etc. If WritableFileWriter keeps the data in
// buf_, then a future Close() or write retry may send the data to
// the underlying file again. If the data does exist in the
// underlying buffer and gets written to the file eventually despite
// returning error, the file may end up with two duplicate pieces of
// data. Therefore, clear the buf_ at the WritableFileWriter layer
// and let caller determine error handling.
buf_.Size(0);
buffered_data_crc32c_checksum_ = 0;
return s;
}
}
IOSTATS_ADD(bytes_written, left);
TEST_KILL_RANDOM("WritableFileWriter::WriteBuffered:0");
// Buffer write is successful, reset the buffer current size to 0 and reset
// the corresponding checksum value
buf_.Size(0);
buffered_data_crc32c_checksum_ = 0;
return s;
}
void WritableFileWriter::UpdateFileChecksum(const Slice& data) {
if (checksum_generator_ != nullptr) {
checksum_generator_->Update(data.data(), data.size());
}
}
// Currently, crc32c checksum is used to calculate the checksum value of the
// content in the input buffer for handoff. In the future, the checksum might be
// calculated from the existing crc32c checksums of the in WAl and Manifest
// records, or even SST file blocks.
// TODO: effectively use the existing checksum of the data being writing to
// generate the crc32c checksum instead of a raw calculation.
void WritableFileWriter::Crc32cHandoffChecksumCalculation(const char* data,
size_t size,
char* buf) {
uint32_t v_crc32c = crc32c::Extend(0, data, size);
EncodeFixed32(buf, v_crc32c);
}
// 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
IOStatus WritableFileWriter::WriteDirect(
Env::IOPriority op_rate_limiter_priority) {
assert(use_direct_io());
IOStatus s;
const size_t alignment = buf_.Alignment();
assert((next_write_offset_ % alignment) == 0);
// Calculate whole page final file advance if all writes succeed
const size_t file_advance =
TruncateToPageBoundary(alignment, buf_.CurrentSize());
// 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.
const size_t leftover_tail = buf_.CurrentSize() - file_advance;
// Round up and pad
buf_.PadToAlignmentWith(0);
const char* src = buf_.BufferStart();
uint64_t write_offset = next_write_offset_;
size_t left = buf_.CurrentSize();
DataVerificationInfo v_info;
char checksum_buf[sizeof(uint32_t)];
IOOptions io_options;
Env::IOPriority rate_limiter_priority_used =
WritableFileWriter::DecideRateLimiterPriority(
writable_file_->GetIOPriority(), op_rate_limiter_priority,
io_options);
while (left > 0) {
// Check how much is allowed
size_t size = left;
if (rate_limiter_ != nullptr &&
rate_limiter_priority_used != Env::IO_TOTAL) {
size = rate_limiter_->RequestToken(left, buf_.Alignment(),
writable_file_->GetIOPriority(),
stats_, RateLimiter::OpType::kWrite);
}
{
IOSTATS_TIMER_GUARD(write_nanos);
TEST_SYNC_POINT("WritableFileWriter::Flush:BeforeAppend");
FileOperationInfo::StartTimePoint start_ts;
if (ShouldNotifyListeners()) {
start_ts = FileOperationInfo::StartNow();
}
// direct writes must be positional
if (perform_data_verification_) {
Crc32cHandoffChecksumCalculation(src, size, checksum_buf);
v_info.checksum = Slice(checksum_buf, sizeof(uint32_t));
s = writable_file_->PositionedAppend(Slice(src, size), write_offset,
io_options, v_info, nullptr);
} else {
s = writable_file_->PositionedAppend(Slice(src, size), write_offset,
io_options, nullptr);
}
if (ShouldNotifyListeners()) {
auto finish_ts = std::chrono::steady_clock::now();
NotifyOnFileWriteFinish(write_offset, size, start_ts, finish_ts, s);
if (!s.ok()) {
NotifyOnIOError(s, FileOperationType::kPositionedAppend, file_name(),
size, write_offset);
}
}
if (!s.ok()) {
buf_.Size(file_advance + leftover_tail);
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;
}
IOStatus WritableFileWriter::WriteDirectWithChecksum(
Env::IOPriority op_rate_limiter_priority) {
assert(use_direct_io());
assert(perform_data_verification_ && buffered_data_with_checksum_);
IOStatus s;
const size_t alignment = buf_.Alignment();
assert((next_write_offset_ % alignment) == 0);
// Calculate whole page final file advance if all writes succeed
const size_t file_advance =
TruncateToPageBoundary(alignment, buf_.CurrentSize());
// 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.
const size_t leftover_tail = buf_.CurrentSize() - file_advance;
// Round up, pad, and combine the checksum.
size_t last_cur_size = buf_.CurrentSize();
buf_.PadToAlignmentWith(0);
size_t padded_size = buf_.CurrentSize() - last_cur_size;
const char* padded_start = buf_.BufferStart() + last_cur_size;
uint32_t padded_checksum = crc32c::Value(padded_start, padded_size);
buffered_data_crc32c_checksum_ = crc32c::Crc32cCombine(
buffered_data_crc32c_checksum_, padded_checksum, padded_size);
const char* src = buf_.BufferStart();
uint64_t write_offset = next_write_offset_;
size_t left = buf_.CurrentSize();
DataVerificationInfo v_info;
char checksum_buf[sizeof(uint32_t)];
IOOptions io_options;
Env::IOPriority rate_limiter_priority_used =
WritableFileWriter::DecideRateLimiterPriority(
writable_file_->GetIOPriority(), op_rate_limiter_priority,
io_options);
// Check how much is allowed. Here, we loop until the rate limiter allows to
// write the entire buffer.
// TODO: need to be improved since it sort of defeats the purpose of the rate
// limiter
size_t data_size = left;
if (rate_limiter_ != nullptr && rate_limiter_priority_used != Env::IO_TOTAL) {
while (data_size > 0) {
size_t size;
size = rate_limiter_->RequestToken(data_size, buf_.Alignment(),
writable_file_->GetIOPriority(),
stats_, RateLimiter::OpType::kWrite);
data_size -= size;
}
}
{
IOSTATS_TIMER_GUARD(write_nanos);
TEST_SYNC_POINT("WritableFileWriter::Flush:BeforeAppend");
FileOperationInfo::StartTimePoint start_ts;
if (ShouldNotifyListeners()) {
start_ts = FileOperationInfo::StartNow();
}
// direct writes must be positional
EncodeFixed32(checksum_buf, buffered_data_crc32c_checksum_);
v_info.checksum = Slice(checksum_buf, sizeof(uint32_t));
s = writable_file_->PositionedAppend(Slice(src, left), write_offset,
io_options, v_info, nullptr);
if (ShouldNotifyListeners()) {
auto finish_ts = std::chrono::steady_clock::now();
NotifyOnFileWriteFinish(write_offset, left, start_ts, finish_ts, s);
if (!s.ok()) {
NotifyOnIOError(s, FileOperationType::kPositionedAppend, file_name(),
left, write_offset);
}
}
if (!s.ok()) {
// In this case, we do not change buffered_data_crc32c_checksum_ because
// it still aligns with the data in the buffer.
buf_.Size(file_advance + leftover_tail);
buffered_data_crc32c_checksum_ =
crc32c::Value(buf_.BufferStart(), buf_.CurrentSize());
return s;
}
}
IOSTATS_ADD(bytes_written, left);
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(). Also the buffer checksum will
// recalculated accordingly.
buf_.RefitTail(file_advance, leftover_tail);
// Adjust the checksum value to align with the data in the buffer
buffered_data_crc32c_checksum_ =
crc32c::Value(buf_.BufferStart(), buf_.CurrentSize());
// 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
Env::IOPriority WritableFileWriter::DecideRateLimiterPriority(
Env::IOPriority writable_file_io_priority,
Env::IOPriority op_rate_limiter_priority, IOOptions& io_options) {
Env::IOPriority rate_limiter_priority{Env::IO_TOTAL};
if (writable_file_io_priority == Env::IO_TOTAL &&
op_rate_limiter_priority == Env::IO_TOTAL) {
rate_limiter_priority = Env::IO_TOTAL;
} else if (writable_file_io_priority == Env::IO_TOTAL) {
rate_limiter_priority = op_rate_limiter_priority;
} else if (op_rate_limiter_priority == Env::IO_TOTAL) {
rate_limiter_priority = writable_file_io_priority;
} else {
rate_limiter_priority = op_rate_limiter_priority;
}
io_options.rate_limiter_priority = rate_limiter_priority;
return rate_limiter_priority;
}
} // namespace ROCKSDB_NAMESPACE