rocksdb/utilities/transactions/write_unprepared_txn_db.h
Maysam Yabandeh c292dc8540 WritePrepared: reduce prepared_mutex_ overhead (#5420)
Summary:
The patch reduces the contention over prepared_mutex_ using these techniques:
1) Move ::RemovePrepared() to be called from the commit callback when we have two write queues.
2) Use two separate mutex for PreparedHeap, one prepared_mutex_ needed for ::RemovePrepared, and one ::push_pop_mutex() needed for ::AddPrepared(). Given that we call ::AddPrepared only from the first write queue and ::RemovePrepared mostly from the 2nd, this will result into each the two write queues not competing with each other over a single mutex. ::RemovePrepared might occasionally need to acquire ::push_pop_mutex() if ::erase() ends up with calling ::pop()
3) Acquire ::push_pop_mutex() on the first callback of the write queue and release it on the last.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5420

Differential Revision: D15741985

Pulled By: maysamyabandeh

fbshipit-source-id: 84ce8016007e88bb6e10da5760ba1f0d26347735
2019-06-10 11:53:31 -07:00

176 lines
6.5 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).
#pragma once
#ifndef ROCKSDB_LITE
#include "utilities/transactions/write_prepared_txn_db.h"
#include "utilities/transactions/write_unprepared_txn.h"
namespace rocksdb {
class WriteUnpreparedTxn;
class WriteUnpreparedTxnDB : public WritePreparedTxnDB {
public:
using WritePreparedTxnDB::WritePreparedTxnDB;
Status Initialize(const std::vector<size_t>& compaction_enabled_cf_indices,
const std::vector<ColumnFamilyHandle*>& handles) override;
Transaction* BeginTransaction(const WriteOptions& write_options,
const TransactionOptions& txn_options,
Transaction* old_txn) override;
// Struct to hold ownership of snapshot and read callback for cleanup.
struct IteratorState;
using WritePreparedTxnDB::NewIterator;
Iterator* NewIterator(const ReadOptions& options,
ColumnFamilyHandle* column_family,
WriteUnpreparedTxn* txn);
private:
Status RollbackRecoveredTransaction(const DBImpl::RecoveredTransaction* rtxn);
};
class WriteUnpreparedCommitEntryPreReleaseCallback : public PreReleaseCallback {
// TODO(lth): Reduce code duplication with
// WritePreparedCommitEntryPreReleaseCallback
public:
// includes_data indicates that the commit also writes non-empty
// CommitTimeWriteBatch to memtable, which needs to be committed separately.
WriteUnpreparedCommitEntryPreReleaseCallback(
WritePreparedTxnDB* db, DBImpl* db_impl,
const std::map<SequenceNumber, size_t>& unprep_seqs,
size_t data_batch_cnt = 0, bool publish_seq = true)
: db_(db),
db_impl_(db_impl),
unprep_seqs_(unprep_seqs),
data_batch_cnt_(data_batch_cnt),
includes_data_(data_batch_cnt_ > 0),
publish_seq_(publish_seq) {
assert(unprep_seqs.size() > 0);
}
virtual Status Callback(SequenceNumber commit_seq,
bool is_mem_disabled __attribute__((__unused__)),
uint64_t, size_t /*index*/,
size_t /*total*/) override {
const uint64_t last_commit_seq = LIKELY(data_batch_cnt_ <= 1)
? commit_seq
: commit_seq + data_batch_cnt_ - 1;
// Recall that unprep_seqs maps (un)prepared_seq => prepare_batch_cnt.
for (const auto& s : unprep_seqs_) {
for (size_t i = 0; i < s.second; i++) {
db_->AddCommitted(s.first + i, last_commit_seq);
}
}
if (includes_data_) {
assert(data_batch_cnt_);
// Commit the data that is accompanied with the commit request
for (size_t i = 0; i < data_batch_cnt_; i++) {
// For commit seq of each batch use the commit seq of the last batch.
// This would make debugging easier by having all the batches having
// the same sequence number.
db_->AddCommitted(commit_seq + i, last_commit_seq);
}
}
if (db_impl_->immutable_db_options().two_write_queues && publish_seq_) {
assert(is_mem_disabled); // implies the 2nd queue
// Publish the sequence number. We can do that here assuming the callback
// is invoked only from one write queue, which would guarantee that the
// publish sequence numbers will be in order, i.e., once a seq is
// published all the seq prior to that are also publishable.
db_impl_->SetLastPublishedSequence(last_commit_seq);
}
// else SequenceNumber that is updated as part of the write already does the
// publishing
return Status::OK();
}
private:
WritePreparedTxnDB* db_;
DBImpl* db_impl_;
const std::map<SequenceNumber, size_t>& unprep_seqs_;
size_t data_batch_cnt_;
// Either because it is commit without prepare or it has a
// CommitTimeWriteBatch
bool includes_data_;
// Should the callback also publishes the commit seq number
bool publish_seq_;
};
class WriteUnpreparedRollbackPreReleaseCallback : public PreReleaseCallback {
// TODO(lth): Reduce code duplication with
// WritePreparedCommitEntryPreReleaseCallback
public:
WriteUnpreparedRollbackPreReleaseCallback(
WritePreparedTxnDB* db, DBImpl* db_impl,
const std::map<SequenceNumber, size_t>& unprep_seqs,
SequenceNumber rollback_seq)
: db_(db),
db_impl_(db_impl),
unprep_seqs_(unprep_seqs),
rollback_seq_(rollback_seq) {
assert(unprep_seqs.size() > 0);
assert(db_impl_->immutable_db_options().two_write_queues);
}
virtual Status Callback(SequenceNumber commit_seq,
bool is_mem_disabled __attribute__((__unused__)),
uint64_t, size_t /*index*/,
size_t /*total*/) override {
assert(is_mem_disabled); // implies the 2nd queue
const uint64_t last_commit_seq = commit_seq;
db_->AddCommitted(rollback_seq_, last_commit_seq);
// Recall that unprep_seqs maps (un)prepared_seq => prepare_batch_cnt.
for (const auto& s : unprep_seqs_) {
for (size_t i = 0; i < s.second; i++) {
db_->AddCommitted(s.first + i, last_commit_seq);
}
}
db_impl_->SetLastPublishedSequence(last_commit_seq);
return Status::OK();
}
private:
WritePreparedTxnDB* db_;
DBImpl* db_impl_;
const std::map<SequenceNumber, size_t>& unprep_seqs_;
SequenceNumber rollback_seq_;
};
struct KeySetBuilder : public WriteBatch::Handler {
WriteUnpreparedTxn* txn_;
bool rollback_merge_operands_;
KeySetBuilder(WriteUnpreparedTxn* txn, bool rollback_merge_operands)
: txn_(txn), rollback_merge_operands_(rollback_merge_operands) {}
Status PutCF(uint32_t cf, const Slice& key, const Slice& val) override;
Status DeleteCF(uint32_t cf, const Slice& key) override;
Status SingleDeleteCF(uint32_t cf, const Slice& key) override;
Status MergeCF(uint32_t cf, const Slice& key, const Slice& val) override;
// Recovered batches do not contain 2PC markers.
Status MarkNoop(bool) override { return Status::InvalidArgument(); }
Status MarkBeginPrepare(bool) override { return Status::InvalidArgument(); }
Status MarkEndPrepare(const Slice&) override {
return Status::InvalidArgument();
}
Status MarkCommit(const Slice&) override { return Status::InvalidArgument(); }
Status MarkRollback(const Slice&) override {
return Status::InvalidArgument();
}
};
} // namespace rocksdb
#endif // ROCKSDB_LITE