blob: 6a7212d607ed2863a77c136323f47fa3c4ea9a3d (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
|
// 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:
// 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_NAMESPACE
|
