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53 lines
1.4 KiB
53 lines
1.4 KiB
// 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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class DB;
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// Abstract handle to particular state of a DB.
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// A Snapshot is an immutable object and can therefore be safely
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// accessed from multiple threads without any external synchronization.
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//
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// To Create a Snapshot, call DB::GetSnapshot().
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// To Destroy a Snapshot, call DB::ReleaseSnapshot(snapshot).
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class Snapshot {
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public:
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virtual SequenceNumber GetSequenceNumber() const = 0;
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// Returns unix time i.e. the number of seconds since the Epoch, 1970-01-01
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// 00:00:00 (UTC).
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virtual int64_t GetUnixTime() const = 0;
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virtual uint64_t GetTimestamp() const = 0;
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protected:
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virtual ~Snapshot();
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};
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// Simple RAII wrapper class for Snapshot.
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// Constructing this object will create a snapshot. Destructing will
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// release the snapshot.
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class ManagedSnapshot {
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public:
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explicit ManagedSnapshot(DB* db);
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// Instead of creating a snapshot, take ownership of the input snapshot.
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ManagedSnapshot(DB* db, const Snapshot* _snapshot);
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~ManagedSnapshot();
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const Snapshot* snapshot();
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private:
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DB* db_;
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const Snapshot* snapshot_;
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};
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} // namespace ROCKSDB_NAMESPACE
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