rocksdb/utilities/transactions/write_prepared_txn.h
Maysam Yabandeh 88d8b2a2f5 WritePrepared Txn: Duplicate Keys, Txn Part
Summary:
This patch takes advantage of memtable being able to detect duplicate <key,seq> and returning TryAgain to handle duplicate keys in WritePrepared Txns. Through WriteBatchWithIndex's index it detects existence of at least a duplicate key in the write batch. If duplicate key was reported, it then pays the cost of counting the number of sub-patches by iterating over the write batch and pass it to DBImpl::Write. DB will make use of the provided batch_count to assign proper sequence numbers before sending them to the WAL. When later inserting the batch to the memtable, it increases the seq each time memtbale reports a duplicate (a sub-patch in our counting) and tries again.
Closes https://github.com/facebook/rocksdb/pull/3455

Differential Revision: D6873699

Pulled By: maysamyabandeh

fbshipit-source-id: db8487526c3a5dc1ddda0ea49f0f979b26ae648d
2018-02-05 18:43:24 -08:00

101 lines
3.6 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 <algorithm>
#include <atomic>
#include <mutex>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>
#include "db/write_callback.h"
#include "rocksdb/db.h"
#include "rocksdb/slice.h"
#include "rocksdb/snapshot.h"
#include "rocksdb/status.h"
#include "rocksdb/types.h"
#include "rocksdb/utilities/transaction.h"
#include "rocksdb/utilities/transaction_db.h"
#include "rocksdb/utilities/write_batch_with_index.h"
#include "util/autovector.h"
#include "utilities/transactions/pessimistic_transaction.h"
#include "utilities/transactions/pessimistic_transaction_db.h"
#include "utilities/transactions/transaction_base.h"
#include "utilities/transactions/transaction_util.h"
namespace rocksdb {
class WritePreparedTxnDB;
// This impl could write to DB also uncomitted data and then later tell apart
// committed data from uncomitted data. Uncommitted data could be after the
// Prepare phase in 2PC (WritePreparedTxn) or before that
// (WriteUnpreparedTxnImpl).
class WritePreparedTxn : public PessimisticTransaction {
public:
WritePreparedTxn(WritePreparedTxnDB* db, const WriteOptions& write_options,
const TransactionOptions& txn_options);
virtual ~WritePreparedTxn() {}
// To make WAL commit markers visible, the snapshot will be based on the last
// seq in the WAL that is also published, LastPublishedSequence, as opposed to
// the last seq in the memtable.
using Transaction::Get;
virtual Status Get(const ReadOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
PinnableSlice* value) override;
// To make WAL commit markers visible, the snapshot will be based on the last
// seq in the WAL that is also published, LastPublishedSequence, as opposed to
// the last seq in the memtable.
using Transaction::GetIterator;
virtual Iterator* GetIterator(const ReadOptions& options) override;
virtual Iterator* GetIterator(const ReadOptions& options,
ColumnFamilyHandle* column_family) override;
private:
friend class WritePreparedTransactionTest_BasicRecoveryTest_Test;
Status PrepareInternal() override;
Status CommitWithoutPrepareInternal() override;
Status CommitBatchInternal(WriteBatch* batch, size_t batch_cnt) override;
// Since the data is already written to memtables at the Prepare phase, the
// commit entails writing only a commit marker in the WAL. The sequence number
// of the commit marker is then the commit timestamp of the transaction. To
// make WAL commit markers visible, the snapshot will be based on the last seq
// in the WAL that is also published, LastPublishedSequence, as opposed to the
// last seq in the memtable.
Status CommitInternal() override;
Status RollbackInternal() override;
virtual Status ValidateSnapshot(ColumnFamilyHandle* column_family,
const Slice& key,
SequenceNumber* tracked_at_seq) override;
virtual Status RebuildFromWriteBatch(WriteBatch* src_batch) override;
// No copying allowed
WritePreparedTxn(const WritePreparedTxn&);
void operator=(const WritePreparedTxn&);
WritePreparedTxnDB* wpt_db_;
// Number of sub-batches in prepare
size_t prepare_batch_cnt_ = 0;
};
} // namespace rocksdb
#endif // ROCKSDB_LITE