mirror of https://github.com/facebook/rocksdb.git
59 lines
1.8 KiB
C++
59 lines
1.8 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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#include "rocksdb/types.h"
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namespace ROCKSDB_NAMESPACE {
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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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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();
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protected:
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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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SnapshotCheckerResult CheckInSnapshot(
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SequenceNumber sequence, SequenceNumber snapshot_sequence) const override;
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private:
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const WritePreparedTxnDB* const txn_db_;
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};
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} // namespace ROCKSDB_NAMESPACE
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