rocksdb/db/snapshot.h
Igor Sugak 62247ffa3b rocksdb: Add missing override
Summary:
When using latest clang (3.6 or 3.7/trunck) rocksdb is failing with many errors. Almost all of them are missing override errors. This diff adds missing override keyword. No manual changes.

Prerequisites: bear and clang 3.5 build with extra tools

```lang=bash
% USE_CLANG=1 bear make all # generate a compilation database http://clang.llvm.org/docs/JSONCompilationDatabase.html
% clang-modernize -p . -include . -add-override
% make format
```

Test Plan:
Make sure all tests are passing.
```lang=bash
% #Use default fb code clang.
% make check
```
Verify less error and no missing override errors.
```lang=bash
% # Have trunk clang present in path.
% ROCKSDB_NO_FBCODE=1 CC=clang CXX=clang++ make
```

Reviewers: igor, kradhakrishnan, rven, meyering, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D34077
2015-02-26 11:28:41 -08:00

106 lines
2.7 KiB
C++

// Copyright (c) 2013, 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.
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include "rocksdb/db.h"
namespace rocksdb {
class SnapshotList;
// Snapshots are kept in a doubly-linked list in the DB.
// Each SnapshotImpl corresponds to a particular sequence number.
class SnapshotImpl : public Snapshot {
public:
SequenceNumber number_; // const after creation
virtual SequenceNumber GetSequenceNumber() const override { return number_; }
private:
friend class SnapshotList;
// SnapshotImpl is kept in a doubly-linked circular list
SnapshotImpl* prev_;
SnapshotImpl* next_;
SnapshotList* list_; // just for sanity checks
int64_t unix_time_;
};
class SnapshotList {
public:
SnapshotList() {
list_.prev_ = &list_;
list_.next_ = &list_;
list_.number_ = 0xFFFFFFFFL; // placeholder marker, for debugging
count_ = 0;
}
bool empty() const { return list_.next_ == &list_; }
SnapshotImpl* oldest() const { assert(!empty()); return list_.next_; }
SnapshotImpl* newest() const { assert(!empty()); return list_.prev_; }
const SnapshotImpl* New(SequenceNumber seq, uint64_t unix_time) {
SnapshotImpl* s = new SnapshotImpl;
s->number_ = seq;
s->unix_time_ = unix_time;
s->list_ = this;
s->next_ = &list_;
s->prev_ = list_.prev_;
s->prev_->next_ = s;
s->next_->prev_ = s;
count_++;
return s;
}
void Delete(const SnapshotImpl* s) {
assert(s->list_ == this);
s->prev_->next_ = s->next_;
s->next_->prev_ = s->prev_;
count_--;
delete s;
}
// retrieve all snapshot numbers. They are sorted in ascending order.
void getAll(std::vector<SequenceNumber>& ret) {
if (empty()) return;
SnapshotImpl* s = &list_;
while (s->next_ != &list_) {
ret.push_back(s->next_->number_);
s = s ->next_;
}
}
// get the sequence number of the most recent snapshot
SequenceNumber GetNewest() {
if (empty()) {
return 0;
}
return newest()->number_;
}
int64_t GetOldestSnapshotTime() const {
if (empty()) {
return 0;
} else {
return oldest()->unix_time_;
}
}
uint64_t count() const { return count_; }
private:
// Dummy head of doubly-linked list of snapshots
SnapshotImpl list_;
uint64_t count_;
};
} // namespace rocksdb