128f532858
Summary: Compaction iterator keep a copy of list of live snapshots at the beginning of compaction, and then query snapshot checker to verify if values of a sequence number is visible to these snapshots. However when the snapshot is released in the middle of compaction, the snapshot checker implementation (i.e. WritePreparedSnapshotChecker) may remove info with the snapshot and may report incorrect result, which lead to values being compacted out when it shouldn't. This patch conservatively keep the values if snapshot checker determines that the snapshots is released. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4858 Differential Revision: D13617146 Pulled By: maysamyabandeh fbshipit-source-id: cf18a94f6f61a94bcff73c280f117b224af5fbc3
62 lines
1.9 KiB
C++
62 lines
1.9 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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#include "rocksdb/types.h"
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namespace rocksdb {
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enum class SnapshotCheckerResult : int {
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kInSnapshot = 0,
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kNotInSnapshot = 1,
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// In case snapshot is released and the checker has no clue whether
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// the given sequence is visible to the snapshot.
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kSnapshotReleased = 2,
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};
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// Callback class that control GC of duplicate keys in flush/compaction.
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class SnapshotChecker {
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public:
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virtual ~SnapshotChecker() {}
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virtual SnapshotCheckerResult CheckInSnapshot(
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SequenceNumber sequence, SequenceNumber snapshot_sequence) const = 0;
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};
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class DisableGCSnapshotChecker : public SnapshotChecker {
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public:
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virtual ~DisableGCSnapshotChecker() {}
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virtual SnapshotCheckerResult CheckInSnapshot(
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SequenceNumber /*sequence*/,
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SequenceNumber /*snapshot_sequence*/) const override {
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// By returning kNotInSnapshot, we prevent all the values from being GCed
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return SnapshotCheckerResult::kNotInSnapshot;
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}
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static DisableGCSnapshotChecker* Instance() { return &instance_; }
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protected:
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static DisableGCSnapshotChecker instance_;
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explicit DisableGCSnapshotChecker() {}
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};
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class WritePreparedTxnDB;
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// Callback class created by WritePreparedTxnDB to check if a key
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// is visible by a snapshot.
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class WritePreparedSnapshotChecker : public SnapshotChecker {
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public:
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explicit WritePreparedSnapshotChecker(WritePreparedTxnDB* txn_db);
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virtual ~WritePreparedSnapshotChecker() {}
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virtual SnapshotCheckerResult CheckInSnapshot(
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SequenceNumber sequence, SequenceNumber snapshot_sequence) const override;
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private:
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#ifndef ROCKSDB_LITE
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const WritePreparedTxnDB* const txn_db_;
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#endif // !ROCKSDB_LITE
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};
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} // namespace rocksdb
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