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