f2827845f9
Summary: The is an optimization to reduce lookup in the CommitCache when querying IsInSnapshot. The optimization takes the smallest uncommitted data at the time that the snapshot was taken and if the sequence number of the read data is lower than that number it assumes the data as committed. To implement this optimization two changes are required: i) The AddPrepared function must be called sequentially to avoid out of order insertion in the PrepareHeap (otherwise the top of the heap does not indicate the smallest prepare in future too), ii) non-2PC transactions also call AddPrepared if they do not commit in one step. Closes https://github.com/facebook/rocksdb/pull/3649 Differential Revision: D7388630 Pulled By: maysamyabandeh fbshipit-source-id: b79506238c17467d590763582960d4d90181c600
109 lines
3.8 KiB
C++
109 lines
3.8 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#pragma once
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#ifndef ROCKSDB_LITE
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#include <algorithm>
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#include <atomic>
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#include <mutex>
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#include <stack>
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#include <string>
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#include <unordered_map>
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#include <vector>
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#include "db/write_callback.h"
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#include "rocksdb/db.h"
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#include "rocksdb/slice.h"
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#include "rocksdb/snapshot.h"
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#include "rocksdb/status.h"
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#include "rocksdb/types.h"
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#include "rocksdb/utilities/transaction.h"
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#include "rocksdb/utilities/transaction_db.h"
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#include "rocksdb/utilities/write_batch_with_index.h"
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#include "util/autovector.h"
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#include "utilities/transactions/pessimistic_transaction.h"
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#include "utilities/transactions/pessimistic_transaction_db.h"
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#include "utilities/transactions/transaction_base.h"
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#include "utilities/transactions/transaction_util.h"
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namespace rocksdb {
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class WritePreparedTxnDB;
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// This impl could write to DB also uncommitted data and then later tell apart
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// committed data from uncommitted data. Uncommitted data could be after the
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// Prepare phase in 2PC (WritePreparedTxn) or before that
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// (WriteUnpreparedTxnImpl).
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class WritePreparedTxn : public PessimisticTransaction {
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public:
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WritePreparedTxn(WritePreparedTxnDB* db, const WriteOptions& write_options,
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const TransactionOptions& txn_options);
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virtual ~WritePreparedTxn() {}
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// To make WAL commit markers visible, the snapshot will be based on the last
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// seq in the WAL that is also published, LastPublishedSequence, as opposed to
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// the last seq in the memtable.
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using Transaction::Get;
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virtual Status Get(const ReadOptions& options,
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ColumnFamilyHandle* column_family, const Slice& key,
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PinnableSlice* value) override;
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// To make WAL commit markers visible, the snapshot will be based on the last
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// seq in the WAL that is also published, LastPublishedSequence, as opposed to
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// the last seq in the memtable.
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using Transaction::GetIterator;
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virtual Iterator* GetIterator(const ReadOptions& options) override;
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virtual Iterator* GetIterator(const ReadOptions& options,
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ColumnFamilyHandle* column_family) override;
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virtual void SetSnapshot() override;
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protected:
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// Override the protected SetId to make it visible to the friend class
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// WritePreparedTxnDB
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inline void SetId(uint64_t id) override { Transaction::SetId(id); }
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private:
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friend class WritePreparedTransactionTest_BasicRecoveryTest_Test;
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friend class WritePreparedTxnDB;
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Status PrepareInternal() override;
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Status CommitWithoutPrepareInternal() override;
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Status CommitBatchInternal(WriteBatch* batch, size_t batch_cnt) override;
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// Since the data is already written to memtables at the Prepare phase, the
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// commit entails writing only a commit marker in the WAL. The sequence number
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// of the commit marker is then the commit timestamp of the transaction. To
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// make WAL commit markers visible, the snapshot will be based on the last seq
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// in the WAL that is also published, LastPublishedSequence, as opposed to the
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// last seq in the memtable.
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Status CommitInternal() override;
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Status RollbackInternal() override;
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virtual Status ValidateSnapshot(ColumnFamilyHandle* column_family,
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const Slice& key,
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SequenceNumber* tracked_at_seq) override;
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virtual Status RebuildFromWriteBatch(WriteBatch* src_batch) override;
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// No copying allowed
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WritePreparedTxn(const WritePreparedTxn&);
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void operator=(const WritePreparedTxn&);
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WritePreparedTxnDB* wpt_db_;
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// Number of sub-batches in prepare
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size_t prepare_batch_cnt_ = 0;
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};
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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