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-rw-r--r--src/rocksdb/db/snapshot_checker.h61
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diff --git a/src/rocksdb/db/snapshot_checker.h b/src/rocksdb/db/snapshot_checker.h
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+// 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
+#include "rocksdb/types.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+enum class SnapshotCheckerResult : int {
+ kInSnapshot = 0,
+ kNotInSnapshot = 1,
+ // In case snapshot is released and the checker has no clue whether
+ // the given sequence is visible to the snapshot.
+ kSnapshotReleased = 2,
+};
+
+// Callback class that control GC of duplicate keys in flush/compaction.
+class SnapshotChecker {
+ public:
+ virtual ~SnapshotChecker() {}
+ virtual SnapshotCheckerResult CheckInSnapshot(
+ SequenceNumber sequence, SequenceNumber snapshot_sequence) const = 0;
+};
+
+class DisableGCSnapshotChecker : public SnapshotChecker {
+ public:
+ virtual ~DisableGCSnapshotChecker() {}
+ virtual SnapshotCheckerResult CheckInSnapshot(
+ SequenceNumber /*sequence*/,
+ SequenceNumber /*snapshot_sequence*/) const override {
+ // By returning kNotInSnapshot, we prevent all the values from being GCed
+ return SnapshotCheckerResult::kNotInSnapshot;
+ }
+ static DisableGCSnapshotChecker* Instance() { return &instance_; }
+
+ protected:
+ static DisableGCSnapshotChecker instance_;
+ explicit DisableGCSnapshotChecker() {}
+};
+
+class WritePreparedTxnDB;
+
+// Callback class created by WritePreparedTxnDB to check if a key
+// is visible by a snapshot.
+class WritePreparedSnapshotChecker : public SnapshotChecker {
+ public:
+ explicit WritePreparedSnapshotChecker(WritePreparedTxnDB* txn_db);
+ virtual ~WritePreparedSnapshotChecker() {}
+
+ virtual SnapshotCheckerResult CheckInSnapshot(
+ SequenceNumber sequence, SequenceNumber snapshot_sequence) const override;
+
+ private:
+#ifndef ROCKSDB_LITE
+ const WritePreparedTxnDB* const txn_db_;
+#endif // !ROCKSDB_LITE
+};
+
+} // namespace ROCKSDB_NAMESPACE