mirror of
https://github.com/facebook/rocksdb.git
synced 2024-11-26 16:30:56 +00:00
49 lines
1.3 KiB
C++
49 lines
1.3 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
|
|
// This source code is licensed under the BSD-style license found in the
|
|
// LICENSE file in the root directory of this source tree. An additional grant
|
|
// of patent rights can be found in the PATENTS file in the same directory.
|
|
|
|
#pragma once
|
|
|
|
#include "rocksdb/types.h"
|
|
|
|
namespace rocksdb {
|
|
|
|
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:
|
|
// returns Snapshot's sequence number
|
|
virtual SequenceNumber GetSequenceNumber() 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
|