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rocksdb/db/db_impl/db_impl_write.cc

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// 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 "db/db_impl/db_impl.h"
#include <cinttypes>
#include "db/error_handler.h"
#include "db/event_helpers.h"
#include "monitoring/perf_context_imp.h"
#include "options/options_helper.h"
#include "test_util/sync_point.h"
namespace rocksdb {
// Convenience methods
Status DBImpl::Put(const WriteOptions& o, ColumnFamilyHandle* column_family,
const Slice& key, const Slice& val) {
return DB::Put(o, column_family, key, val);
}
Status DBImpl::Merge(const WriteOptions& o, ColumnFamilyHandle* column_family,
const Slice& key, const Slice& val) {
auto cfh = reinterpret_cast<ColumnFamilyHandleImpl*>(column_family);
if (!cfh->cfd()->ioptions()->merge_operator) {
return Status::NotSupported("Provide a merge_operator when opening DB");
} else {
return DB::Merge(o, column_family, key, val);
}
}
Status DBImpl::Delete(const WriteOptions& write_options,
ColumnFamilyHandle* column_family, const Slice& key) {
return DB::Delete(write_options, column_family, key);
}
Status DBImpl::SingleDelete(const WriteOptions& write_options,
ColumnFamilyHandle* column_family,
const Slice& key) {
return DB::SingleDelete(write_options, column_family, key);
}
void DBImpl::SetRecoverableStatePreReleaseCallback(
PreReleaseCallback* callback) {
recoverable_state_pre_release_callback_.reset(callback);
}
Status DBImpl::Write(const WriteOptions& write_options, WriteBatch* my_batch) {
return WriteImpl(write_options, my_batch, nullptr, nullptr);
}
#ifndef ROCKSDB_LITE
Status DBImpl::WriteWithCallback(const WriteOptions& write_options,
WriteBatch* my_batch,
WriteCallback* callback) {
return WriteImpl(write_options, my_batch, callback, nullptr);
}
#endif // ROCKSDB_LITE
// The main write queue. This is the only write queue that updates LastSequence.
// When using one write queue, the same sequence also indicates the last
// published sequence.
Status DBImpl::WriteImpl(const WriteOptions& write_options,
WriteBatch* my_batch, WriteCallback* callback,
uint64_t* log_used, uint64_t log_ref,
bool disable_memtable, uint64_t* seq_used,
size_t batch_cnt,
PreReleaseCallback* pre_release_callback) {
assert(!seq_per_batch_ || batch_cnt != 0);
if (my_batch == nullptr) {
return Status::Corruption("Batch is nullptr!");
}
if (tracer_) {
InstrumentedMutexLock lock(&trace_mutex_);
if (tracer_) {
tracer_->Write(my_batch);
}
}
if (write_options.sync && write_options.disableWAL) {
return Status::InvalidArgument("Sync writes has to enable WAL.");
}
if (two_write_queues_ && immutable_db_options_.enable_pipelined_write) {
return Status::NotSupported(
"pipelined_writes is not compatible with concurrent prepares");
}
if (seq_per_batch_ && immutable_db_options_.enable_pipelined_write) {
// TODO(yiwu): update pipeline write with seq_per_batch and batch_cnt
return Status::NotSupported(
"pipelined_writes is not compatible with seq_per_batch");
}
if (immutable_db_options_.unordered_write &&
immutable_db_options_.enable_pipelined_write) {
return Status::NotSupported(
"pipelined_writes is not compatible with unordered_write");
}
// Otherwise IsLatestPersistentState optimization does not make sense
assert(!WriteBatchInternal::IsLatestPersistentState(my_batch) ||
disable_memtable);
Status status;
if (write_options.low_pri) {
status = ThrottleLowPriWritesIfNeeded(write_options, my_batch);
if (!status.ok()) {
return status;
}
}
if (two_write_queues_ && disable_memtable) {
AssignOrder assign_order =
seq_per_batch_ ? kDoAssignOrder : kDontAssignOrder;
// Otherwise it is WAL-only Prepare batches in WriteCommitted policy and
// they don't consume sequence.
return WriteImplWALOnly(&nonmem_write_thread_, write_options, my_batch,
callback, log_used, log_ref, seq_used, batch_cnt,
pre_release_callback, assign_order,
kDontPublishLastSeq, disable_memtable);
}
if (immutable_db_options_.unordered_write) {
const size_t sub_batch_cnt = batch_cnt != 0
? batch_cnt
// every key is a sub-batch consuming a seq
: WriteBatchInternal::Count(my_batch);
uint64_t seq;
// Use a write thread to i) optimize for WAL write, ii) publish last
// sequence in in increasing order, iii) call pre_release_callback serially
status = WriteImplWALOnly(&write_thread_, write_options, my_batch, callback,
log_used, log_ref, &seq, sub_batch_cnt,
pre_release_callback, kDoAssignOrder,
kDoPublishLastSeq, disable_memtable);
TEST_SYNC_POINT("DBImpl::WriteImpl:UnorderedWriteAfterWriteWAL");
if (!status.ok()) {
return status;
}
if (seq_used) {
*seq_used = seq;
}
if (!disable_memtable) {
TEST_SYNC_POINT("DBImpl::WriteImpl:BeforeUnorderedWriteMemtable");
status = UnorderedWriteMemtable(write_options, my_batch, callback,
log_ref, seq, sub_batch_cnt);
}
return status;
}
if (immutable_db_options_.enable_pipelined_write) {
return PipelinedWriteImpl(write_options, my_batch, callback, log_used,
log_ref, disable_memtable, seq_used);
}
PERF_TIMER_GUARD(write_pre_and_post_process_time);
WriteThread::Writer w(write_options, my_batch, callback, log_ref,
disable_memtable, batch_cnt, pre_release_callback);
if (!write_options.disableWAL) {
RecordTick(stats_, WRITE_WITH_WAL);
}
StopWatch write_sw(env_, immutable_db_options_.statistics.get(), DB_WRITE);
write_thread_.JoinBatchGroup(&w);
if (w.state == WriteThread::STATE_PARALLEL_MEMTABLE_WRITER) {
// we are a non-leader in a parallel group
if (w.ShouldWriteToMemtable()) {
PERF_TIMER_STOP(write_pre_and_post_process_time);
PERF_TIMER_GUARD(write_memtable_time);
ColumnFamilyMemTablesImpl column_family_memtables(
versions_->GetColumnFamilySet());
w.status = WriteBatchInternal::InsertInto(
&w, w.sequence, &column_family_memtables, &flush_scheduler_,
&trim_history_scheduler_,
write_options.ignore_missing_column_families, 0 /*log_number*/, this,
true /*concurrent_memtable_writes*/, seq_per_batch_, w.batch_cnt,
batch_per_txn_, write_options.memtable_insert_hint_per_batch);
PERF_TIMER_START(write_pre_and_post_process_time);
}
if (write_thread_.CompleteParallelMemTableWriter(&w)) {
// we're responsible for exit batch group
// TODO(myabandeh): propagate status to write_group
auto last_sequence = w.write_group->last_sequence;
versions_->SetLastSequence(last_sequence);
MemTableInsertStatusCheck(w.status);
write_thread_.ExitAsBatchGroupFollower(&w);
}
assert(w.state == WriteThread::STATE_COMPLETED);
// STATE_COMPLETED conditional below handles exit
status = w.FinalStatus();
}
if (w.state == WriteThread::STATE_COMPLETED) {
if (log_used != nullptr) {
*log_used = w.log_used;
}
if (seq_used != nullptr) {
*seq_used = w.sequence;
}
// write is complete and leader has updated sequence
return w.FinalStatus();
}
// else we are the leader of the write batch group
assert(w.state == WriteThread::STATE_GROUP_LEADER);
// Once reaches this point, the current writer "w" will try to do its write
// job. It may also pick up some of the remaining writers in the "writers_"
// when it finds suitable, and finish them in the same write batch.
// This is how a write job could be done by the other writer.
WriteContext write_context;
WriteThread::WriteGroup write_group;
bool in_parallel_group = false;
uint64_t last_sequence = kMaxSequenceNumber;
mutex_.Lock();
bool need_log_sync = write_options.sync;
bool need_log_dir_sync = need_log_sync && !log_dir_synced_;
if (!two_write_queues_ || !disable_memtable) {
// With concurrent writes we do preprocess only in the write thread that
// also does write to memtable to avoid sync issue on shared data structure
// with the other thread
// PreprocessWrite does its own perf timing.
PERF_TIMER_STOP(write_pre_and_post_process_time);
status = PreprocessWrite(write_options, &need_log_sync, &write_context);
if (!two_write_queues_) {
// Assign it after ::PreprocessWrite since the sequence might advance
// inside it by WriteRecoverableState
last_sequence = versions_->LastSequence();
}
PERF_TIMER_START(write_pre_and_post_process_time);
}
log::Writer* log_writer = logs_.back().writer;
mutex_.Unlock();
// Add to log and apply to memtable. We can release the lock
// during this phase since &w is currently responsible for logging
// and protects against concurrent loggers and concurrent writes
// into memtables
TEST_SYNC_POINT("DBImpl::WriteImpl:BeforeLeaderEnters");
last_batch_group_size_ =
write_thread_.EnterAsBatchGroupLeader(&w, &write_group);
if (status.ok()) {
// Rules for when we can update the memtable concurrently
// 1. supported by memtable
// 2. Puts are not okay if inplace_update_support
// 3. Merges are not okay
//
// Rules 1..2 are enforced by checking the options
// during startup (CheckConcurrentWritesSupported), so if
// options.allow_concurrent_memtable_write is true then they can be
// assumed to be true. Rule 3 is checked for each batch. We could
// relax rules 2 if we could prevent write batches from referring
// more than once to a particular key.
bool parallel = immutable_db_options_.allow_concurrent_memtable_write &&
write_group.size > 1;
size_t total_count = 0;
size_t valid_batches = 0;
size_t total_byte_size = 0;
size_t pre_release_callback_cnt = 0;
for (auto* writer : write_group) {
if (writer->CheckCallback(this)) {
valid_batches += writer->batch_cnt;
if (writer->ShouldWriteToMemtable()) {
total_count += WriteBatchInternal::Count(writer->batch);
parallel = parallel && !writer->batch->HasMerge();
}
total_byte_size = WriteBatchInternal::AppendedByteSize(
total_byte_size, WriteBatchInternal::ByteSize(writer->batch));
if (writer->pre_release_callback) {
pre_release_callback_cnt++;
}
}
}
// Note about seq_per_batch_: either disableWAL is set for the entire write
// group or not. In either case we inc seq for each write batch with no
// failed callback. This means that there could be a batch with
// disalbe_memtable in between; although we do not write this batch to
// memtable it still consumes a seq. Otherwise, if !seq_per_batch_, we inc
// the seq per valid written key to mem.
size_t seq_inc = seq_per_batch_ ? valid_batches : total_count;
const bool concurrent_update = two_write_queues_;
// Update stats while we are an exclusive group leader, so we know
// that nobody else can be writing to these particular stats.
// We're optimistic, updating the stats before we successfully
// commit. That lets us release our leader status early.
auto stats = default_cf_internal_stats_;
stats->AddDBStats(InternalStats::kIntStatsNumKeysWritten, total_count,
concurrent_update);
RecordTick(stats_, NUMBER_KEYS_WRITTEN, total_count);
stats->AddDBStats(InternalStats::kIntStatsBytesWritten, total_byte_size,
concurrent_update);
RecordTick(stats_, BYTES_WRITTEN, total_byte_size);
stats->AddDBStats(InternalStats::kIntStatsWriteDoneBySelf, 1,
concurrent_update);
RecordTick(stats_, WRITE_DONE_BY_SELF);
auto write_done_by_other = write_group.size - 1;
if (write_done_by_other > 0) {
stats->AddDBStats(InternalStats::kIntStatsWriteDoneByOther,
write_done_by_other, concurrent_update);
RecordTick(stats_, WRITE_DONE_BY_OTHER, write_done_by_other);
}
RecordInHistogram(stats_, BYTES_PER_WRITE, total_byte_size);
if (write_options.disableWAL) {
has_unpersisted_data_.store(true, std::memory_order_relaxed);
}
PERF_TIMER_STOP(write_pre_and_post_process_time);
if (!two_write_queues_) {
if (status.ok() && !write_options.disableWAL) {
PERF_TIMER_GUARD(write_wal_time);
status = WriteToWAL(write_group, log_writer, log_used, need_log_sync,
need_log_dir_sync, last_sequence + 1);
}
} else {
if (status.ok() && !write_options.disableWAL) {
PERF_TIMER_GUARD(write_wal_time);
// LastAllocatedSequence is increased inside WriteToWAL under
// wal_write_mutex_ to ensure ordered events in WAL
status = ConcurrentWriteToWAL(write_group, log_used, &last_sequence,
seq_inc);
} else {
// Otherwise we inc seq number for memtable writes
last_sequence = versions_->FetchAddLastAllocatedSequence(seq_inc);
}
}
assert(last_sequence != kMaxSequenceNumber);
const SequenceNumber current_sequence = last_sequence + 1;
last_sequence += seq_inc;
// PreReleaseCallback is called after WAL write and before memtable write
if (status.ok()) {
SequenceNumber next_sequence = current_sequence;
size_t index = 0;
// Note: the logic for advancing seq here must be consistent with the
// logic in WriteBatchInternal::InsertInto(write_group...) as well as
// with WriteBatchInternal::InsertInto(write_batch...) that is called on
// the merged batch during recovery from the WAL.
for (auto* writer : write_group) {
if (writer->CallbackFailed()) {
continue;
}
writer->sequence = next_sequence;
if (writer->pre_release_callback) {
Status ws = writer->pre_release_callback->Callback(
writer->sequence, disable_memtable, writer->log_used, index++,
pre_release_callback_cnt);
if (!ws.ok()) {
status = ws;
break;
}
}
if (seq_per_batch_) {
assert(writer->batch_cnt);
next_sequence += writer->batch_cnt;
} else if (writer->ShouldWriteToMemtable()) {
next_sequence += WriteBatchInternal::Count(writer->batch);
}
}
}
if (status.ok()) {
PERF_TIMER_GUARD(write_memtable_time);
if (!parallel) {
// w.sequence will be set inside InsertInto
w.status = WriteBatchInternal::InsertInto(
write_group, current_sequence, column_family_memtables_.get(),
&flush_scheduler_, &trim_history_scheduler_,
write_options.ignore_missing_column_families,
0 /*recovery_log_number*/, this, parallel, seq_per_batch_,
batch_per_txn_);
} else {
write_group.last_sequence = last_sequence;
write_thread_.LaunchParallelMemTableWriters(&write_group);
in_parallel_group = true;
// Each parallel follower is doing each own writes. The leader should
// also do its own.
if (w.ShouldWriteToMemtable()) {
ColumnFamilyMemTablesImpl column_family_memtables(
versions_->GetColumnFamilySet());
assert(w.sequence == current_sequence);
w.status = WriteBatchInternal::InsertInto(
&w, w.sequence, &column_family_memtables, &flush_scheduler_,
&trim_history_scheduler_,
write_options.ignore_missing_column_families, 0 /*log_number*/,
this, true /*concurrent_memtable_writes*/, seq_per_batch_,
w.batch_cnt, batch_per_txn_,
write_options.memtable_insert_hint_per_batch);
}
}
if (seq_used != nullptr) {
*seq_used = w.sequence;
}
}
}
PERF_TIMER_START(write_pre_and_post_process_time);
if (!w.CallbackFailed()) {
WriteStatusCheck(status);
}
if (need_log_sync) {
mutex_.Lock();
MarkLogsSynced(logfile_number_, need_log_dir_sync, status);
mutex_.Unlock();
// Requesting sync with two_write_queues_ is expected to be very rare. We
// hence provide a simple implementation that is not necessarily efficient.
if (two_write_queues_) {
if (manual_wal_flush_) {
status = FlushWAL(true);
} else {
status = SyncWAL();
}
}
}
bool should_exit_batch_group = true;
if (in_parallel_group) {
// CompleteParallelWorker returns true if this thread should
// handle exit, false means somebody else did
should_exit_batch_group = write_thread_.CompleteParallelMemTableWriter(&w);
}
if (should_exit_batch_group) {
if (status.ok()) {
// Note: if we are to resume after non-OK statuses we need to revisit how
// we reacts to non-OK statuses here.
versions_->SetLastSequence(last_sequence);
}
MemTableInsertStatusCheck(w.status);
write_thread_.ExitAsBatchGroupLeader(write_group, status);
}
if (status.ok()) {
status = w.FinalStatus();
}
return status;
}
Status DBImpl::PipelinedWriteImpl(const WriteOptions& write_options,
WriteBatch* my_batch, WriteCallback* callback,
uint64_t* log_used, uint64_t log_ref,
bool disable_memtable, uint64_t* seq_used) {
PERF_TIMER_GUARD(write_pre_and_post_process_time);
StopWatch write_sw(env_, immutable_db_options_.statistics.get(), DB_WRITE);
WriteContext write_context;
WriteThread::Writer w(write_options, my_batch, callback, log_ref,
disable_memtable);
write_thread_.JoinBatchGroup(&w);
if (w.state == WriteThread::STATE_GROUP_LEADER) {
WriteThread::WriteGroup wal_write_group;
if (w.callback && !w.callback->AllowWriteBatching()) {
write_thread_.WaitForMemTableWriters();
}
mutex_.Lock();
bool need_log_sync = !write_options.disableWAL && write_options.sync;
bool need_log_dir_sync = need_log_sync && !log_dir_synced_;
// PreprocessWrite does its own perf timing.
PERF_TIMER_STOP(write_pre_and_post_process_time);
w.status = PreprocessWrite(write_options, &need_log_sync, &write_context);
PERF_TIMER_START(write_pre_and_post_process_time);
log::Writer* log_writer = logs_.back().writer;
mutex_.Unlock();
// This can set non-OK status if callback fail.
last_batch_group_size_ =
write_thread_.EnterAsBatchGroupLeader(&w, &wal_write_group);
const SequenceNumber current_sequence =
write_thread_.UpdateLastSequence(versions_->LastSequence()) + 1;
size_t total_count = 0;
size_t total_byte_size = 0;
if (w.status.ok()) {
SequenceNumber next_sequence = current_sequence;
for (auto writer : wal_write_group) {
if (writer->CheckCallback(this)) {
if (writer->ShouldWriteToMemtable()) {
writer->sequence = next_sequence;
size_t count = WriteBatchInternal::Count(writer->batch);
next_sequence += count;
total_count += count;
}
total_byte_size = WriteBatchInternal::AppendedByteSize(
total_byte_size, WriteBatchInternal::ByteSize(writer->batch));
}
}
if (w.disable_wal) {
has_unpersisted_data_.store(true, std::memory_order_relaxed);
}
write_thread_.UpdateLastSequence(current_sequence + total_count - 1);
}
auto stats = default_cf_internal_stats_;
stats->AddDBStats(InternalStats::kIntStatsNumKeysWritten, total_count);
RecordTick(stats_, NUMBER_KEYS_WRITTEN, total_count);
stats->AddDBStats(InternalStats::kIntStatsBytesWritten, total_byte_size);
RecordTick(stats_, BYTES_WRITTEN, total_byte_size);
RecordInHistogram(stats_, BYTES_PER_WRITE, total_byte_size);
PERF_TIMER_STOP(write_pre_and_post_process_time);
if (w.status.ok() && !write_options.disableWAL) {
PERF_TIMER_GUARD(write_wal_time);
stats->AddDBStats(InternalStats::kIntStatsWriteDoneBySelf, 1);
RecordTick(stats_, WRITE_DONE_BY_SELF, 1);
if (wal_write_group.size > 1) {
stats->AddDBStats(InternalStats::kIntStatsWriteDoneByOther,
wal_write_group.size - 1);
RecordTick(stats_, WRITE_DONE_BY_OTHER, wal_write_group.size - 1);
}
w.status = WriteToWAL(wal_write_group, log_writer, log_used,
need_log_sync, need_log_dir_sync, current_sequence);
}
if (!w.CallbackFailed()) {
WriteStatusCheck(w.status);
}
if (need_log_sync) {
mutex_.Lock();
MarkLogsSynced(logfile_number_, need_log_dir_sync, w.status);
mutex_.Unlock();
}
write_thread_.ExitAsBatchGroupLeader(wal_write_group, w.status);
}
WriteThread::WriteGroup memtable_write_group;
if (w.state == WriteThread::STATE_MEMTABLE_WRITER_LEADER) {
PERF_TIMER_GUARD(write_memtable_time);
assert(w.ShouldWriteToMemtable());
write_thread_.EnterAsMemTableWriter(&w, &memtable_write_group);
if (memtable_write_group.size > 1 &&
immutable_db_options_.allow_concurrent_memtable_write) {
write_thread_.LaunchParallelMemTableWriters(&memtable_write_group);
} else {
memtable_write_group.status = WriteBatchInternal::InsertInto(
memtable_write_group, w.sequence, column_family_memtables_.get(),
&flush_scheduler_, &trim_history_scheduler_,
write_options.ignore_missing_column_families, 0 /*log_number*/, this,
false /*concurrent_memtable_writes*/, seq_per_batch_, batch_per_txn_);
versions_->SetLastSequence(memtable_write_group.last_sequence);
write_thread_.ExitAsMemTableWriter(&w, memtable_write_group);
}
}
if (w.state == WriteThread::STATE_PARALLEL_MEMTABLE_WRITER) {
assert(w.ShouldWriteToMemtable());
ColumnFamilyMemTablesImpl column_family_memtables(
versions_->GetColumnFamilySet());
w.status = WriteBatchInternal::InsertInto(
&w, w.sequence, &column_family_memtables, &flush_scheduler_,
&trim_history_scheduler_, write_options.ignore_missing_column_families,
0 /*log_number*/, this, true /*concurrent_memtable_writes*/,
false /*seq_per_batch*/, 0 /*batch_cnt*/, true /*batch_per_txn*/,
write_options.memtable_insert_hint_per_batch);
if (write_thread_.CompleteParallelMemTableWriter(&w)) {
MemTableInsertStatusCheck(w.status);
versions_->SetLastSequence(w.write_group->last_sequence);
write_thread_.ExitAsMemTableWriter(&w, *w.write_group);
}
}
if (seq_used != nullptr) {
*seq_used = w.sequence;
}
assert(w.state == WriteThread::STATE_COMPLETED);
return w.FinalStatus();
}
Status DBImpl::UnorderedWriteMemtable(const WriteOptions& write_options,
WriteBatch* my_batch,
WriteCallback* callback, uint64_t log_ref,
SequenceNumber seq,
const size_t sub_batch_cnt) {
PERF_TIMER_GUARD(write_pre_and_post_process_time);
StopWatch write_sw(env_, immutable_db_options_.statistics.get(), DB_WRITE);
WriteThread::Writer w(write_options, my_batch, callback, log_ref,
false /*disable_memtable*/);
if (w.CheckCallback(this) && w.ShouldWriteToMemtable()) {
w.sequence = seq;
size_t total_count = WriteBatchInternal::Count(my_batch);
InternalStats* stats = default_cf_internal_stats_;
stats->AddDBStats(InternalStats::kIntStatsNumKeysWritten, total_count);
RecordTick(stats_, NUMBER_KEYS_WRITTEN, total_count);
ColumnFamilyMemTablesImpl column_family_memtables(
versions_->GetColumnFamilySet());
w.status = WriteBatchInternal::InsertInto(
&w, w.sequence, &column_family_memtables, &flush_scheduler_,
&trim_history_scheduler_, write_options.ignore_missing_column_families,
0 /*log_number*/, this, true /*concurrent_memtable_writes*/,
seq_per_batch_, sub_batch_cnt, true /*batch_per_txn*/,
write_options.memtable_insert_hint_per_batch);
WriteStatusCheck(w.status);
if (write_options.disableWAL) {
has_unpersisted_data_.store(true, std::memory_order_relaxed);
}
}
size_t pending_cnt = pending_memtable_writes_.fetch_sub(1) - 1;
if (pending_cnt == 0) {
// switch_cv_ waits until pending_memtable_writes_ = 0. Locking its mutex
// before notify ensures that cv is in waiting state when it is notified
// thus not missing the update to pending_memtable_writes_ even though it is
// not modified under the mutex.
std::lock_guard<std::mutex> lck(switch_mutex_);
switch_cv_.notify_all();
}
if (!w.FinalStatus().ok()) {
return w.FinalStatus();
}
return Status::OK();
}
// The 2nd write queue. If enabled it will be used only for WAL-only writes.
// This is the only queue that updates LastPublishedSequence which is only
// applicable in a two-queue setting.
Status DBImpl::WriteImplWALOnly(
WriteThread* write_thread, const WriteOptions& write_options,
WriteBatch* my_batch, WriteCallback* callback, uint64_t* log_used,
const uint64_t log_ref, uint64_t* seq_used, const size_t sub_batch_cnt,
PreReleaseCallback* pre_release_callback, const AssignOrder assign_order,
const PublishLastSeq publish_last_seq, const bool disable_memtable) {
Status status;
PERF_TIMER_GUARD(write_pre_and_post_process_time);
WriteThread::Writer w(write_options, my_batch, callback, log_ref,
disable_memtable, sub_batch_cnt, pre_release_callback);
RecordTick(stats_, WRITE_WITH_WAL);
StopWatch write_sw(env_, immutable_db_options_.statistics.get(), DB_WRITE);
write_thread->JoinBatchGroup(&w);
assert(w.state != WriteThread::STATE_PARALLEL_MEMTABLE_WRITER);
if (w.state == WriteThread::STATE_COMPLETED) {
if (log_used != nullptr) {
*log_used = w.log_used;
}
if (seq_used != nullptr) {
*seq_used = w.sequence;
}
return w.FinalStatus();
}
// else we are the leader of the write batch group
assert(w.state == WriteThread::STATE_GROUP_LEADER);
if (publish_last_seq == kDoPublishLastSeq) {
// Currently we only use kDoPublishLastSeq in unordered_write
assert(immutable_db_options_.unordered_write);
WriteContext write_context;
if (error_handler_.IsDBStopped()) {
status = error_handler_.GetBGError();
}
// TODO(myabandeh): Make preliminary checks thread-safe so we could do them
// without paying the cost of obtaining the mutex.
if (status.ok()) {
InstrumentedMutexLock l(&mutex_);
bool need_log_sync = false;
status = PreprocessWrite(write_options, &need_log_sync, &write_context);
WriteStatusCheck(status);
}
if (!status.ok()) {
WriteThread::WriteGroup write_group;
write_thread->EnterAsBatchGroupLeader(&w, &write_group);
write_thread->ExitAsBatchGroupLeader(write_group, status);
return status;
}
}
WriteThread::WriteGroup write_group;
uint64_t last_sequence;
write_thread->EnterAsBatchGroupLeader(&w, &write_group);
// Note: no need to update last_batch_group_size_ here since the batch writes
// to WAL only
size_t pre_release_callback_cnt = 0;
size_t total_byte_size = 0;
for (auto* writer : write_group) {
if (writer->CheckCallback(this)) {
total_byte_size = WriteBatchInternal::AppendedByteSize(
total_byte_size, WriteBatchInternal::ByteSize(writer->batch));
if (writer->pre_release_callback) {
pre_release_callback_cnt++;
}
}
}
const bool concurrent_update = true;
// Update stats while we are an exclusive group leader, so we know
// that nobody else can be writing to these particular stats.
// We're optimistic, updating the stats before we successfully
// commit. That lets us release our leader status early.
auto stats = default_cf_internal_stats_;
stats->AddDBStats(InternalStats::kIntStatsBytesWritten, total_byte_size,
concurrent_update);
RecordTick(stats_, BYTES_WRITTEN, total_byte_size);
stats->AddDBStats(InternalStats::kIntStatsWriteDoneBySelf, 1,
concurrent_update);
RecordTick(stats_, WRITE_DONE_BY_SELF);
auto write_done_by_other = write_group.size - 1;
if (write_done_by_other > 0) {
stats->AddDBStats(InternalStats::kIntStatsWriteDoneByOther,
write_done_by_other, concurrent_update);
RecordTick(stats_, WRITE_DONE_BY_OTHER, write_done_by_other);
}
RecordInHistogram(stats_, BYTES_PER_WRITE, total_byte_size);
PERF_TIMER_STOP(write_pre_and_post_process_time);
PERF_TIMER_GUARD(write_wal_time);
// LastAllocatedSequence is increased inside WriteToWAL under
// wal_write_mutex_ to ensure ordered events in WAL
size_t seq_inc = 0 /* total_count */;
if (assign_order == kDoAssignOrder) {
size_t total_batch_cnt = 0;
for (auto* writer : write_group) {
assert(writer->batch_cnt || !seq_per_batch_);
if (!writer->CallbackFailed()) {
total_batch_cnt += writer->batch_cnt;
}
}
seq_inc = total_batch_cnt;
}
if (!write_options.disableWAL) {
status =
ConcurrentWriteToWAL(write_group, log_used, &last_sequence, seq_inc);
} else {
// Otherwise we inc seq number to do solely the seq allocation
last_sequence = versions_->FetchAddLastAllocatedSequence(seq_inc);
}
size_t memtable_write_cnt = 0;
auto curr_seq = last_sequence + 1;
for (auto* writer : write_group) {
if (writer->CallbackFailed()) {
continue;
}
writer->sequence = curr_seq;
if (assign_order == kDoAssignOrder) {
assert(writer->batch_cnt || !seq_per_batch_);
curr_seq += writer->batch_cnt;
}
if (!writer->disable_memtable) {
memtable_write_cnt++;
}
// else seq advances only by memtable writes
}
if (status.ok() && write_options.sync) {
assert(!write_options.disableWAL);
// Requesting sync with two_write_queues_ is expected to be very rare. We
// hance provide a simple implementation that is not necessarily efficient.
if (manual_wal_flush_) {
status = FlushWAL(true);
} else {
status = SyncWAL();
}
}
PERF_TIMER_START(write_pre_and_post_process_time);
if (!w.CallbackFailed()) {
WriteStatusCheck(status);
}
if (status.ok()) {
size_t index = 0;
for (auto* writer : write_group) {
if (!writer->CallbackFailed() && writer->pre_release_callback) {
assert(writer->sequence != kMaxSequenceNumber);
Status ws = writer->pre_release_callback->Callback(
writer->sequence, disable_memtable, writer->log_used, index++,
pre_release_callback_cnt);
if (!ws.ok()) {
status = ws;
break;
}
}
}
}
if (publish_last_seq == kDoPublishLastSeq) {
versions_->SetLastSequence(last_sequence + seq_inc);
// Currently we only use kDoPublishLastSeq in unordered_write
assert(immutable_db_options_.unordered_write);
}
if (immutable_db_options_.unordered_write && status.ok()) {
pending_memtable_writes_ += memtable_write_cnt;
}
write_thread->ExitAsBatchGroupLeader(write_group, status);
if (status.ok()) {
status = w.FinalStatus();
}
if (seq_used != nullptr) {
*seq_used = w.sequence;
}
return status;
}
void DBImpl::WriteStatusCheck(const Status& status) {
// Is setting bg_error_ enough here? This will at least stop
// compaction and fail any further writes.
if (immutable_db_options_.paranoid_checks && !status.ok() &&
!status.IsBusy() && !status.IsIncomplete()) {
mutex_.Lock();
error_handler_.SetBGError(status, BackgroundErrorReason::kWriteCallback);
mutex_.Unlock();
}
}
void DBImpl::MemTableInsertStatusCheck(const Status& status) {
// A non-OK status here indicates that the state implied by the
// WAL has diverged from the in-memory state. This could be
// because of a corrupt write_batch (very bad), or because the
// client specified an invalid column family and didn't specify
// ignore_missing_column_families.
if (!status.ok()) {
mutex_.Lock();
assert(!error_handler_.IsBGWorkStopped());
error_handler_.SetBGError(status, BackgroundErrorReason::kMemTable);
mutex_.Unlock();
}
}
Status DBImpl::PreprocessWrite(const WriteOptions& write_options,
bool* need_log_sync,
WriteContext* write_context) {
mutex_.AssertHeld();
assert(write_context != nullptr && need_log_sync != nullptr);
Status status;
if (error_handler_.IsDBStopped()) {
status = error_handler_.GetBGError();
}
PERF_TIMER_GUARD(write_scheduling_flushes_compactions_time);
assert(!single_column_family_mode_ ||
versions_->GetColumnFamilySet()->NumberOfColumnFamilies() == 1);
if (UNLIKELY(status.ok() && !single_column_family_mode_ &&
total_log_size_ > GetMaxTotalWalSize())) {
WaitForPendingWrites();
status = SwitchWAL(write_context);
}
if (UNLIKELY(status.ok() && write_buffer_manager_->ShouldFlush())) {
// Before a new memtable is added in SwitchMemtable(),
// write_buffer_manager_->ShouldFlush() will keep returning true. If another
// thread is writing to another DB with the same write buffer, they may also
// be flushed. We may end up with flushing much more DBs than needed. It's
// suboptimal but still correct.
WaitForPendingWrites();
status = HandleWriteBufferFull(write_context);
}
if (UNLIKELY(status.ok() && !trim_history_scheduler_.Empty())) {
status = TrimMemtableHistory(write_context);
}
if (UNLIKELY(status.ok() && !flush_scheduler_.Empty())) {
WaitForPendingWrites();
status = ScheduleFlushes(write_context);
}
PERF_TIMER_STOP(write_scheduling_flushes_compactions_time);
PERF_TIMER_GUARD(write_pre_and_post_process_time);
if (UNLIKELY(status.ok() && (write_controller_.IsStopped() ||
write_controller_.NeedsDelay()))) {
PERF_TIMER_STOP(write_pre_and_post_process_time);
PERF_TIMER_GUARD(write_delay_time);
// We don't know size of curent batch so that we always use the size
// for previous one. It might create a fairness issue that expiration
// might happen for smaller writes but larger writes can go through.
// Can optimize it if it is an issue.
status = DelayWrite(last_batch_group_size_, write_options);
PERF_TIMER_START(write_pre_and_post_process_time);
}
if (status.ok() && *need_log_sync) {
// Wait until the parallel syncs are finished. Any sync process has to sync
// the front log too so it is enough to check the status of front()
// We do a while loop since log_sync_cv_ is signalled when any sync is
// finished
// Note: there does not seem to be a reason to wait for parallel sync at
// this early step but it is not important since parallel sync (SyncWAL) and
// need_log_sync are usually not used together.
while (logs_.front().getting_synced) {
log_sync_cv_.Wait();
}
for (auto& log : logs_) {
assert(!log.getting_synced);
// This is just to prevent the logs to be synced by a parallel SyncWAL
// call. We will do the actual syncing later after we will write to the
// WAL.
// Note: there does not seem to be a reason to set this early before we
// actually write to the WAL
log.getting_synced = true;
}
} else {
*need_log_sync = false;
}
return status;
}
WriteBatch* DBImpl::MergeBatch(const WriteThread::WriteGroup& write_group,
WriteBatch* tmp_batch, size_t* write_with_wal,
WriteBatch** to_be_cached_state) {
assert(write_with_wal != nullptr);
assert(tmp_batch != nullptr);
assert(*to_be_cached_state == nullptr);
WriteBatch* merged_batch = nullptr;
*write_with_wal = 0;
auto* leader = write_group.leader;
assert(!leader->disable_wal); // Same holds for all in the batch group
if (write_group.size == 1 && !leader->CallbackFailed() &&
leader->batch->GetWalTerminationPoint().is_cleared()) {
// we simply write the first WriteBatch to WAL if the group only
// contains one batch, that batch should be written to the WAL,
// and the batch is not wanting to be truncated
merged_batch = leader->batch;
if (WriteBatchInternal::IsLatestPersistentState(merged_batch)) {
*to_be_cached_state = merged_batch;
}
*write_with_wal = 1;
} else {
// WAL needs all of the batches flattened into a single batch.
// We could avoid copying here with an iov-like AddRecord
// interface
merged_batch = tmp_batch;
for (auto writer : write_group) {
if (!writer->CallbackFailed()) {
WriteBatchInternal::Append(merged_batch, writer->batch,
/*WAL_only*/ true);
if (WriteBatchInternal::IsLatestPersistentState(writer->batch)) {
// We only need to cache the last of such write batch
*to_be_cached_state = writer->batch;
}
(*write_with_wal)++;
}
}
}
return merged_batch;
}
// When two_write_queues_ is disabled, this function is called from the only
// write thread. Otherwise this must be called holding log_write_mutex_.
Status DBImpl::WriteToWAL(const WriteBatch& merged_batch,
log::Writer* log_writer, uint64_t* log_used,
uint64_t* log_size) {
assert(log_size != nullptr);
Slice log_entry = WriteBatchInternal::Contents(&merged_batch);
*log_size = log_entry.size();
// When two_write_queues_ WriteToWAL has to be protected from concurretn calls
// from the two queues anyway and log_write_mutex_ is already held. Otherwise
// if manual_wal_flush_ is enabled we need to protect log_writer->AddRecord
// from possible concurrent calls via the FlushWAL by the application.
const bool needs_locking = manual_wal_flush_ && !two_write_queues_;
// Due to performance cocerns of missed branch prediction penalize the new
// manual_wal_flush_ feature (by UNLIKELY) instead of the more common case
// when we do not need any locking.
if (UNLIKELY(needs_locking)) {
log_write_mutex_.Lock();
}
Status status = log_writer->AddRecord(log_entry);
if (UNLIKELY(needs_locking)) {
log_write_mutex_.Unlock();
}
if (log_used != nullptr) {
*log_used = logfile_number_;
}
total_log_size_ += log_entry.size();
// TODO(myabandeh): it might be unsafe to access alive_log_files_.back() here
// since alive_log_files_ might be modified concurrently
alive_log_files_.back().AddSize(log_entry.size());
log_empty_ = false;
return status;
}
Status DBImpl::WriteToWAL(const WriteThread::WriteGroup& write_group,
log::Writer* log_writer, uint64_t* log_used,
bool need_log_sync, bool need_log_dir_sync,
SequenceNumber sequence) {
Status status;
assert(!write_group.leader->disable_wal);
// Same holds for all in the batch group
size_t write_with_wal = 0;
WriteBatch* to_be_cached_state = nullptr;
WriteBatch* merged_batch = MergeBatch(write_group, &tmp_batch_,
&write_with_wal, &to_be_cached_state);
if (merged_batch == write_group.leader->batch) {
write_group.leader->log_used = logfile_number_;
} else if (write_with_wal > 1) {
for (auto writer : write_group) {
writer->log_used = logfile_number_;
}
}
WriteBatchInternal::SetSequence(merged_batch, sequence);
uint64_t log_size;
status = WriteToWAL(*merged_batch, log_writer, log_used, &log_size);
if (to_be_cached_state) {
cached_recoverable_state_ = *to_be_cached_state;
cached_recoverable_state_empty_ = false;
}
if (status.ok() && need_log_sync) {
StopWatch sw(env_, stats_, WAL_FILE_SYNC_MICROS);
// It's safe to access logs_ with unlocked mutex_ here because:
// - we've set getting_synced=true for all logs,
// so other threads won't pop from logs_ while we're here,
// - only writer thread can push to logs_, and we're in
// writer thread, so no one will push to logs_,
// - as long as other threads don't modify it, it's safe to read
// from std::deque from multiple threads concurrently.
for (auto& log : logs_) {
status = log.writer->file()->Sync(immutable_db_options_.use_fsync);
if (!status.ok()) {
break;
}
}
if (status.ok() && need_log_dir_sync) {
// We only sync WAL directory the first time WAL syncing is
// requested, so that in case users never turn on WAL sync,
// we can avoid the disk I/O in the write code path.
status = directories_.GetWalDir()->Fsync();
}
}
if (merged_batch == &tmp_batch_) {
tmp_batch_.Clear();
}
if (status.ok()) {
auto stats = default_cf_internal_stats_;
if (need_log_sync) {
stats->AddDBStats(InternalStats::kIntStatsWalFileSynced, 1);
RecordTick(stats_, WAL_FILE_SYNCED);
}
stats->AddDBStats(InternalStats::kIntStatsWalFileBytes, log_size);
RecordTick(stats_, WAL_FILE_BYTES, log_size);
stats->AddDBStats(InternalStats::kIntStatsWriteWithWal, write_with_wal);
RecordTick(stats_, WRITE_WITH_WAL, write_with_wal);
}
return status;
}
Status DBImpl::ConcurrentWriteToWAL(const WriteThread::WriteGroup& write_group,
uint64_t* log_used,
SequenceNumber* last_sequence,
size_t seq_inc) {
Status status;
assert(!write_group.leader->disable_wal);
// Same holds for all in the batch group
WriteBatch tmp_batch;
size_t write_with_wal = 0;
WriteBatch* to_be_cached_state = nullptr;
WriteBatch* merged_batch =
MergeBatch(write_group, &tmp_batch, &write_with_wal, &to_be_cached_state);
// We need to lock log_write_mutex_ since logs_ and alive_log_files might be
// pushed back concurrently
log_write_mutex_.Lock();
if (merged_batch == write_group.leader->batch) {
write_group.leader->log_used = logfile_number_;
} else if (write_with_wal > 1) {
for (auto writer : write_group) {
writer->log_used = logfile_number_;
}
}
*last_sequence = versions_->FetchAddLastAllocatedSequence(seq_inc);
auto sequence = *last_sequence + 1;
WriteBatchInternal::SetSequence(merged_batch, sequence);
log::Writer* log_writer = logs_.back().writer;
uint64_t log_size;
status = WriteToWAL(*merged_batch, log_writer, log_used, &log_size);
if (to_be_cached_state) {
cached_recoverable_state_ = *to_be_cached_state;
cached_recoverable_state_empty_ = false;
}
log_write_mutex_.Unlock();
if (status.ok()) {
const bool concurrent = true;
auto stats = default_cf_internal_stats_;
stats->AddDBStats(InternalStats::kIntStatsWalFileBytes, log_size,
concurrent);
RecordTick(stats_, WAL_FILE_BYTES, log_size);
stats->AddDBStats(InternalStats::kIntStatsWriteWithWal, write_with_wal,
concurrent);
RecordTick(stats_, WRITE_WITH_WAL, write_with_wal);
}
return status;
}
Status DBImpl::WriteRecoverableState() {
mutex_.AssertHeld();
if (!cached_recoverable_state_empty_) {
bool dont_care_bool;
SequenceNumber next_seq;
if (two_write_queues_) {
log_write_mutex_.Lock();
}
SequenceNumber seq;
if (two_write_queues_) {
seq = versions_->FetchAddLastAllocatedSequence(0);
} else {
seq = versions_->LastSequence();
}
WriteBatchInternal::SetSequence(&cached_recoverable_state_, seq + 1);
auto status = WriteBatchInternal::InsertInto(
&cached_recoverable_state_, column_family_memtables_.get(),
&flush_scheduler_, &trim_history_scheduler_, true,
0 /*recovery_log_number*/, this, false /* concurrent_memtable_writes */,
&next_seq, &dont_care_bool, seq_per_batch_);
auto last_seq = next_seq - 1;
if (two_write_queues_) {
versions_->FetchAddLastAllocatedSequence(last_seq - seq);
versions_->SetLastPublishedSequence(last_seq);
}
versions_->SetLastSequence(last_seq);
if (two_write_queues_) {
log_write_mutex_.Unlock();
}
if (status.ok() && recoverable_state_pre_release_callback_) {
const bool DISABLE_MEMTABLE = true;
for (uint64_t sub_batch_seq = seq + 1;
sub_batch_seq < next_seq && status.ok(); sub_batch_seq++) {
uint64_t const no_log_num = 0;
// Unlock it since the callback might end up locking mutex. e.g.,
// AddCommitted -> AdvanceMaxEvictedSeq -> GetSnapshotListFromDB
mutex_.Unlock();
status = recoverable_state_pre_release_callback_->Callback(
sub_batch_seq, !DISABLE_MEMTABLE, no_log_num, 0, 1);
mutex_.Lock();
}
}
if (status.ok()) {
cached_recoverable_state_.Clear();
cached_recoverable_state_empty_ = true;
}
return status;
}
return Status::OK();
}
void DBImpl::SelectColumnFamiliesForAtomicFlush(
autovector<ColumnFamilyData*>* cfds) {
for (ColumnFamilyData* cfd : *versions_->GetColumnFamilySet()) {
if (cfd->IsDropped()) {
continue;
}
if (cfd->imm()->NumNotFlushed() != 0 || !cfd->mem()->IsEmpty() ||
!cached_recoverable_state_empty_.load()) {
cfds->push_back(cfd);
}
}
}
// Assign sequence number for atomic flush.
void DBImpl::AssignAtomicFlushSeq(const autovector<ColumnFamilyData*>& cfds) {
assert(immutable_db_options_.atomic_flush);
auto seq = versions_->LastSequence();
for (auto cfd : cfds) {
cfd->imm()->AssignAtomicFlushSeq(seq);
}
}
Status DBImpl::SwitchWAL(WriteContext* write_context) {
mutex_.AssertHeld();
assert(write_context != nullptr);
Status status;
if (alive_log_files_.begin()->getting_flushed) {
return status;
}
auto oldest_alive_log = alive_log_files_.begin()->number;
bool flush_wont_release_oldest_log = false;
if (allow_2pc()) {
auto oldest_log_with_uncommitted_prep =
logs_with_prep_tracker_.FindMinLogContainingOutstandingPrep();
assert(oldest_log_with_uncommitted_prep == 0 ||
oldest_log_with_uncommitted_prep >= oldest_alive_log);
if (oldest_log_with_uncommitted_prep > 0 &&
oldest_log_with_uncommitted_prep == oldest_alive_log) {
if (unable_to_release_oldest_log_) {
// we already attempted to flush all column families dependent on
// the oldest alive log but the log still contained uncommitted
// transactions so there is still nothing that we can do.
return status;
} else {
ROCKS_LOG_WARN(
immutable_db_options_.info_log,
"Unable to release oldest log due to uncommitted transaction");
unable_to_release_oldest_log_ = true;
flush_wont_release_oldest_log = true;
}
}
}
if (!flush_wont_release_oldest_log) {
// we only mark this log as getting flushed if we have successfully
// flushed all data in this log. If this log contains outstanding prepared
// transactions then we cannot flush this log until those transactions are
// commited.
unable_to_release_oldest_log_ = false;
alive_log_files_.begin()->getting_flushed = true;
}
ROCKS_LOG_INFO(
immutable_db_options_.info_log,
"Flushing all column families with data in WAL number %" PRIu64
". Total log size is %" PRIu64 " while max_total_wal_size is %" PRIu64,
oldest_alive_log, total_log_size_.load(), GetMaxTotalWalSize());
// no need to refcount because drop is happening in write thread, so can't
// happen while we're in the write thread
autovector<ColumnFamilyData*> cfds;
if (immutable_db_options_.atomic_flush) {
SelectColumnFamiliesForAtomicFlush(&cfds);
} else {
for (auto cfd : *versions_->GetColumnFamilySet()) {
if (cfd->IsDropped()) {
continue;
}
if (cfd->OldestLogToKeep() <= oldest_alive_log) {
cfds.push_back(cfd);
}
}
MaybeFlushStatsCF(&cfds);
}
WriteThread::Writer nonmem_w;
if (two_write_queues_) {
nonmem_write_thread_.EnterUnbatched(&nonmem_w, &mutex_);
}
for (const auto cfd : cfds) {
cfd->Ref();
status = SwitchMemtable(cfd, write_context);
cfd->UnrefAndTryDelete();
if (!status.ok()) {
break;
}
}
if (two_write_queues_) {
nonmem_write_thread_.ExitUnbatched(&nonmem_w);
}
if (status.ok()) {
if (immutable_db_options_.atomic_flush) {
AssignAtomicFlushSeq(cfds);
}
for (auto cfd : cfds) {
cfd->imm()->FlushRequested();
}
FlushRequest flush_req;
GenerateFlushRequest(cfds, &flush_req);
SchedulePendingFlush(flush_req, FlushReason::kWriteBufferManager);
MaybeScheduleFlushOrCompaction();
}
return status;
}
Status DBImpl::HandleWriteBufferFull(WriteContext* write_context) {
mutex_.AssertHeld();
assert(write_context != nullptr);
Status status;
// Before a new memtable is added in SwitchMemtable(),
// write_buffer_manager_->ShouldFlush() will keep returning true. If another
// thread is writing to another DB with the same write buffer, they may also
// be flushed. We may end up with flushing much more DBs than needed. It's
// suboptimal but still correct.
ROCKS_LOG_INFO(
immutable_db_options_.info_log,
"Flushing column family with largest mem table size. Write buffer is "
"using %" ROCKSDB_PRIszt " bytes out of a total of %" ROCKSDB_PRIszt ".",
write_buffer_manager_->memory_usage(),
write_buffer_manager_->buffer_size());
// no need to refcount because drop is happening in write thread, so can't
// happen while we're in the write thread
autovector<ColumnFamilyData*> cfds;
if (immutable_db_options_.atomic_flush) {
SelectColumnFamiliesForAtomicFlush(&cfds);
} else {
ColumnFamilyData* cfd_picked = nullptr;
SequenceNumber seq_num_for_cf_picked = kMaxSequenceNumber;
for (auto cfd : *versions_->GetColumnFamilySet()) {
if (cfd->IsDropped()) {
continue;
}
if (!cfd->mem()->IsEmpty()) {
// We only consider active mem table, hoping immutable memtable is
// already in the process of flushing.
uint64_t seq = cfd->mem()->GetCreationSeq();
if (cfd_picked == nullptr || seq < seq_num_for_cf_picked) {
cfd_picked = cfd;
seq_num_for_cf_picked = seq;
}
}
}
if (cfd_picked != nullptr) {
cfds.push_back(cfd_picked);
}
MaybeFlushStatsCF(&cfds);
}
WriteThread::Writer nonmem_w;
if (two_write_queues_) {
nonmem_write_thread_.EnterUnbatched(&nonmem_w, &mutex_);
}
for (const auto cfd : cfds) {
if (cfd->mem()->IsEmpty()) {
continue;
}
cfd->Ref();
status = SwitchMemtable(cfd, write_context);
cfd->UnrefAndTryDelete();
if (!status.ok()) {
break;
}
}
if (two_write_queues_) {
nonmem_write_thread_.ExitUnbatched(&nonmem_w);
}
if (status.ok()) {
if (immutable_db_options_.atomic_flush) {
AssignAtomicFlushSeq(cfds);
}
for (const auto cfd : cfds) {
cfd->imm()->FlushRequested();
}
FlushRequest flush_req;
GenerateFlushRequest(cfds, &flush_req);
SchedulePendingFlush(flush_req, FlushReason::kWriteBufferFull);
MaybeScheduleFlushOrCompaction();
}
return status;
}
uint64_t DBImpl::GetMaxTotalWalSize() const {
mutex_.AssertHeld();
return mutable_db_options_.max_total_wal_size == 0
? 4 * max_total_in_memory_state_
: mutable_db_options_.max_total_wal_size;
}
// REQUIRES: mutex_ is held
// REQUIRES: this thread is currently at the front of the writer queue
Status DBImpl::DelayWrite(uint64_t num_bytes,
const WriteOptions& write_options) {
uint64_t time_delayed = 0;
bool delayed = false;
{
StopWatch sw(env_, stats_, WRITE_STALL, &time_delayed);
uint64_t delay = write_controller_.GetDelay(env_, num_bytes);
if (delay > 0) {
if (write_options.no_slowdown) {
return Status::Incomplete("Write stall");
}
TEST_SYNC_POINT("DBImpl::DelayWrite:Sleep");
// Notify write_thread_ about the stall so it can setup a barrier and
// fail any pending writers with no_slowdown
write_thread_.BeginWriteStall();
TEST_SYNC_POINT("DBImpl::DelayWrite:BeginWriteStallDone");
mutex_.Unlock();
// We will delay the write until we have slept for delay ms or
// we don't need a delay anymore
const uint64_t kDelayInterval = 1000;
uint64_t stall_end = sw.start_time() + delay;
while (write_controller_.NeedsDelay()) {
if (env_->NowMicros() >= stall_end) {
// We already delayed this write `delay` microseconds
break;
}
delayed = true;
// Sleep for 0.001 seconds
env_->SleepForMicroseconds(kDelayInterval);
}
mutex_.Lock();
write_thread_.EndWriteStall();
}
// Don't wait if there's a background error, even if its a soft error. We
// might wait here indefinitely as the background compaction may never
// finish successfully, resulting in the stall condition lasting
// indefinitely
while (error_handler_.GetBGError().ok() && write_controller_.IsStopped()) {
if (write_options.no_slowdown) {
return Status::Incomplete("Write stall");
}
delayed = true;
// Notify write_thread_ about the stall so it can setup a barrier and
// fail any pending writers with no_slowdown
write_thread_.BeginWriteStall();
TEST_SYNC_POINT("DBImpl::DelayWrite:Wait");
bg_cv_.Wait();
write_thread_.EndWriteStall();
}
}
assert(!delayed || !write_options.no_slowdown);
if (delayed) {
default_cf_internal_stats_->AddDBStats(
InternalStats::kIntStatsWriteStallMicros, time_delayed);
RecordTick(stats_, STALL_MICROS, time_delayed);
}
// If DB is not in read-only mode and write_controller is not stopping
// writes, we can ignore any background errors and allow the write to
// proceed
Status s;
if (write_controller_.IsStopped()) {
// If writes are still stopped, it means we bailed due to a background
// error
s = Status::Incomplete(error_handler_.GetBGError().ToString());
}
if (error_handler_.IsDBStopped()) {
s = error_handler_.GetBGError();
}
return s;
}
Status DBImpl::ThrottleLowPriWritesIfNeeded(const WriteOptions& write_options,
WriteBatch* my_batch) {
assert(write_options.low_pri);
// This is called outside the DB mutex. Although it is safe to make the call,
// the consistency condition is not guaranteed to hold. It's OK to live with
// it in this case.
// If we need to speed compaction, it means the compaction is left behind
// and we start to limit low pri writes to a limit.
if (write_controller_.NeedSpeedupCompaction()) {
if (allow_2pc() && (my_batch->HasCommit() || my_batch->HasRollback())) {
// For 2PC, we only rate limit prepare, not commit.
return Status::OK();
}
if (write_options.no_slowdown) {
return Status::Incomplete();
} else {
assert(my_batch != nullptr);
// Rate limit those writes. The reason that we don't completely wait
// is that in case the write is heavy, low pri writes may never have
// a chance to run. Now we guarantee we are still slowly making
// progress.
PERF_TIMER_GUARD(write_delay_time);
write_controller_.low_pri_rate_limiter()->Request(
my_batch->GetDataSize(), Env::IO_HIGH, nullptr /* stats */,
RateLimiter::OpType::kWrite);
}
}
return Status::OK();
}
void DBImpl::MaybeFlushStatsCF(autovector<ColumnFamilyData*>* cfds) {
assert(cfds != nullptr);
if (!cfds->empty() && immutable_db_options_.persist_stats_to_disk) {
ColumnFamilyData* cfd_stats =
versions_->GetColumnFamilySet()->GetColumnFamily(
kPersistentStatsColumnFamilyName);
if (cfd_stats != nullptr && !cfd_stats->mem()->IsEmpty()) {
for (ColumnFamilyData* cfd : *cfds) {
if (cfd == cfd_stats) {
// stats CF already included in cfds
return;
}
}
// force flush stats CF when its log number is less than all other CF's
// log numbers
bool force_flush_stats_cf = true;
for (auto* loop_cfd : *versions_->GetColumnFamilySet()) {
if (loop_cfd == cfd_stats) {
continue;
}
if (loop_cfd->GetLogNumber() <= cfd_stats->GetLogNumber()) {
force_flush_stats_cf = false;
}
}
if (force_flush_stats_cf) {
cfds->push_back(cfd_stats);
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"Force flushing stats CF with automated flush "
"to avoid holding old logs");
}
}
}
}
Status DBImpl::TrimMemtableHistory(WriteContext* context) {
autovector<ColumnFamilyData*> cfds;
ColumnFamilyData* tmp_cfd;
while ((tmp_cfd = trim_history_scheduler_.TakeNextColumnFamily()) !=
nullptr) {
cfds.push_back(tmp_cfd);
}
for (auto& cfd : cfds) {
autovector<MemTable*> to_delete;
cfd->imm()->TrimHistory(&to_delete, cfd->mem()->ApproximateMemoryUsage());
if (!to_delete.empty()) {
for (auto m : to_delete) {
delete m;
}
context->superversion_context.NewSuperVersion();
assert(context->superversion_context.new_superversion.get() != nullptr);
cfd->InstallSuperVersion(&context->superversion_context, &mutex_);
}
if (cfd->UnrefAndTryDelete()) {
cfd = nullptr;
}
}
return Status::OK();
}
Status DBImpl::ScheduleFlushes(WriteContext* context) {
autovector<ColumnFamilyData*> cfds;
if (immutable_db_options_.atomic_flush) {
SelectColumnFamiliesForAtomicFlush(&cfds);
for (auto cfd : cfds) {
cfd->Ref();
}
flush_scheduler_.Clear();
} else {
ColumnFamilyData* tmp_cfd;
while ((tmp_cfd = flush_scheduler_.TakeNextColumnFamily()) != nullptr) {
cfds.push_back(tmp_cfd);
}
MaybeFlushStatsCF(&cfds);
}
Status status;
WriteThread::Writer nonmem_w;
if (two_write_queues_) {
nonmem_write_thread_.EnterUnbatched(&nonmem_w, &mutex_);
}
for (auto& cfd : cfds) {
if (!cfd->mem()->IsEmpty()) {
status = SwitchMemtable(cfd, context);
}
if (cfd->UnrefAndTryDelete()) {
cfd = nullptr;
}
if (!status.ok()) {
break;
}
}
if (two_write_queues_) {
nonmem_write_thread_.ExitUnbatched(&nonmem_w);
}
if (status.ok()) {
if (immutable_db_options_.atomic_flush) {
AssignAtomicFlushSeq(cfds);
}
FlushRequest flush_req;
GenerateFlushRequest(cfds, &flush_req);
SchedulePendingFlush(flush_req, FlushReason::kWriteBufferFull);
MaybeScheduleFlushOrCompaction();
}
return status;
}
#ifndef ROCKSDB_LITE
void DBImpl::NotifyOnMemTableSealed(ColumnFamilyData* /*cfd*/,
const MemTableInfo& mem_table_info) {
if (immutable_db_options_.listeners.size() == 0U) {
return;
}
if (shutting_down_.load(std::memory_order_acquire)) {
return;
}
for (auto listener : immutable_db_options_.listeners) {
listener->OnMemTableSealed(mem_table_info);
}
}
#endif // ROCKSDB_LITE
// REQUIRES: mutex_ is held
// REQUIRES: this thread is currently at the front of the writer queue
// REQUIRES: this thread is currently at the front of the 2nd writer queue if
// two_write_queues_ is true (This is to simplify the reasoning.)
Status DBImpl::SwitchMemtable(ColumnFamilyData* cfd, WriteContext* context) {
mutex_.AssertHeld();
WriteThread::Writer nonmem_w;
std::unique_ptr<WritableFile> lfile;
log::Writer* new_log = nullptr;
MemTable* new_mem = nullptr;
// Recoverable state is persisted in WAL. After memtable switch, WAL might
// be deleted, so we write the state to memtable to be persisted as well.
Status s = WriteRecoverableState();
if (!s.ok()) {
return s;
}
// Attempt to switch to a new memtable and trigger flush of old.
// Do this without holding the dbmutex lock.
assert(versions_->prev_log_number() == 0);
if (two_write_queues_) {
log_write_mutex_.Lock();
}
bool creating_new_log = !log_empty_;
if (two_write_queues_) {
log_write_mutex_.Unlock();
}
uint64_t recycle_log_number = 0;
if (creating_new_log && immutable_db_options_.recycle_log_file_num &&
!log_recycle_files_.empty()) {
recycle_log_number = log_recycle_files_.front();
log_recycle_files_.pop_front();
}
uint64_t new_log_number =
creating_new_log ? versions_->NewFileNumber() : logfile_number_;
const MutableCFOptions mutable_cf_options = *cfd->GetLatestMutableCFOptions();
// Set memtable_info for memtable sealed callback
#ifndef ROCKSDB_LITE
MemTableInfo memtable_info;
memtable_info.cf_name = cfd->GetName();
memtable_info.first_seqno = cfd->mem()->GetFirstSequenceNumber();
memtable_info.earliest_seqno = cfd->mem()->GetEarliestSequenceNumber();
memtable_info.num_entries = cfd->mem()->num_entries();
memtable_info.num_deletes = cfd->mem()->num_deletes();
#endif // ROCKSDB_LITE
// Log this later after lock release. It may be outdated, e.g., if background
// flush happens before logging, but that should be ok.
int num_imm_unflushed = cfd->imm()->NumNotFlushed();
const auto preallocate_block_size =
GetWalPreallocateBlockSize(mutable_cf_options.write_buffer_size);
mutex_.Unlock();
if (creating_new_log) {
// TODO: Write buffer size passed in should be max of all CF's instead
// of mutable_cf_options.write_buffer_size.
s = CreateWAL(new_log_number, recycle_log_number, preallocate_block_size,
&new_log);
}
if (s.ok()) {
SequenceNumber seq = versions_->LastSequence();
new_mem = cfd->ConstructNewMemtable(mutable_cf_options, seq);
context->superversion_context.NewSuperVersion();
}
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"[%s] New memtable created with log file: #%" PRIu64
". Immutable memtables: %d.\n",
cfd->GetName().c_str(), new_log_number, num_imm_unflushed);
mutex_.Lock();
if (s.ok() && creating_new_log) {
log_write_mutex_.Lock();
assert(new_log != nullptr);
if (!logs_.empty()) {
// Alway flush the buffer of the last log before switching to a new one
log::Writer* cur_log_writer = logs_.back().writer;
s = cur_log_writer->WriteBuffer();
if (!s.ok()) {
ROCKS_LOG_WARN(immutable_db_options_.info_log,
"[%s] Failed to switch from #%" PRIu64 " to #%" PRIu64
" WAL file\n",
cfd->GetName().c_str(), cur_log_writer->get_log_number(),
new_log_number);
}
}
if (s.ok()) {
logfile_number_ = new_log_number;
log_empty_ = true;
log_dir_synced_ = false;
logs_.emplace_back(logfile_number_, new_log);
alive_log_files_.push_back(LogFileNumberSize(logfile_number_));
}
log_write_mutex_.Unlock();
}
if (!s.ok()) {
// how do we fail if we're not creating new log?
assert(creating_new_log);
if (new_mem) {
delete new_mem;
}
if (new_log) {
delete new_log;
}
SuperVersion* new_superversion =
context->superversion_context.new_superversion.release();
if (new_superversion != nullptr) {
delete new_superversion;
}
// We may have lost data from the WritableFileBuffer in-memory buffer for
// the current log, so treat it as a fatal error and set bg_error
error_handler_.SetBGError(s, BackgroundErrorReason::kMemTable);
// Read back bg_error in order to get the right severity
s = error_handler_.GetBGError();
return s;
}
for (auto loop_cfd : *versions_->GetColumnFamilySet()) {
// all this is just optimization to delete logs that
// are no longer needed -- if CF is empty, that means it
// doesn't need that particular log to stay alive, so we just
// advance the log number. no need to persist this in the manifest
if (loop_cfd->mem()->GetFirstSequenceNumber() == 0 &&
loop_cfd->imm()->NumNotFlushed() == 0) {
if (creating_new_log) {
loop_cfd->SetLogNumber(logfile_number_);
}
loop_cfd->mem()->SetCreationSeq(versions_->LastSequence());
}
}
cfd->mem()->SetNextLogNumber(logfile_number_);
cfd->imm()->Add(cfd->mem(), &context->memtables_to_free_);
new_mem->Ref();
cfd->SetMemtable(new_mem);
InstallSuperVersionAndScheduleWork(cfd, &context->superversion_context,
mutable_cf_options);
#ifndef ROCKSDB_LITE
mutex_.Unlock();
// Notify client that memtable is sealed, now that we have successfully
// installed a new memtable
NotifyOnMemTableSealed(cfd, memtable_info);
mutex_.Lock();
#endif // ROCKSDB_LITE
return s;
}
size_t DBImpl::GetWalPreallocateBlockSize(uint64_t write_buffer_size) const {
mutex_.AssertHeld();
size_t bsize =
static_cast<size_t>(write_buffer_size / 10 + write_buffer_size);
// Some users might set very high write_buffer_size and rely on
// max_total_wal_size or other parameters to control the WAL size.
if (mutable_db_options_.max_total_wal_size > 0) {
bsize = std::min<size_t>(
bsize, static_cast<size_t>(mutable_db_options_.max_total_wal_size));
}
if (immutable_db_options_.db_write_buffer_size > 0) {
bsize = std::min<size_t>(bsize, immutable_db_options_.db_write_buffer_size);
}
if (immutable_db_options_.write_buffer_manager &&
immutable_db_options_.write_buffer_manager->enabled()) {
bsize = std::min<size_t>(
bsize, immutable_db_options_.write_buffer_manager->buffer_size());
}
return bsize;
}
// Default implementations of convenience methods that subclasses of DB
// can call if they wish
Status DB::Put(const WriteOptions& opt, ColumnFamilyHandle* column_family,
const Slice& key, const Slice& value) {
if (nullptr == opt.timestamp) {
// Pre-allocate size of write batch conservatively.
// 8 bytes are taken by header, 4 bytes for count, 1 byte for type,
// and we allocate 11 extra bytes for key length, as well as value length.
WriteBatch batch(key.size() + value.size() + 24);
Status s = batch.Put(column_family, key, value);
if (!s.ok()) {
return s;
}
return Write(opt, &batch);
}
const Slice* ts = opt.timestamp;
assert(nullptr != ts);
size_t ts_sz = ts->size();
WriteBatch batch(key.size() + ts_sz + value.size() + 24, /*max_bytes=*/0,
ts_sz);
Status s = batch.Put(column_family, key, value);
if (!s.ok()) {
return s;
}
s = batch.AssignTimestamp(*ts);
if (!s.ok()) {
return s;
}
return Write(opt, &batch);
}
Status DB::Delete(const WriteOptions& opt, ColumnFamilyHandle* column_family,
const Slice& key) {
WriteBatch batch;
batch.Delete(column_family, key);
return Write(opt, &batch);
}
Status DB::SingleDelete(const WriteOptions& opt,
ColumnFamilyHandle* column_family, const Slice& key) {
WriteBatch batch;
batch.SingleDelete(column_family, key);
return Write(opt, &batch);
}
Status DB::DeleteRange(const WriteOptions& opt,
ColumnFamilyHandle* column_family,
const Slice& begin_key, const Slice& end_key) {
WriteBatch batch;
batch.DeleteRange(column_family, begin_key, end_key);
return Write(opt, &batch);
}
Status DB::Merge(const WriteOptions& opt, ColumnFamilyHandle* column_family,
const Slice& key, const Slice& value) {
WriteBatch batch;
Status s = batch.Merge(column_family, key, value);
if (!s.ok()) {
return s;
}
return Write(opt, &batch);
}
} // namespace rocksdb