73c0a33346
Summary: Currently, compaction filter is run on internal key older than the oldest snapshot, which is incorrect. Compaction filter should really be run on the most recent internal key when there is no external snapshot. Test Plan: make check; db_stress Reviewers: dhruba Reviewed By: dhruba Differential Revision: https://reviews.facebook.net/D10641
86 lines
2.1 KiB
C++
86 lines
2.1 KiB
C++
// 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.
|
|
|
|
#ifndef STORAGE_LEVELDB_DB_SNAPSHOT_H_
|
|
#define STORAGE_LEVELDB_DB_SNAPSHOT_H_
|
|
|
|
#include "leveldb/db.h"
|
|
|
|
namespace leveldb {
|
|
|
|
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
|
|
|
|
private:
|
|
friend class SnapshotList;
|
|
|
|
// SnapshotImpl is kept in a doubly-linked circular list
|
|
SnapshotImpl* prev_;
|
|
SnapshotImpl* next_;
|
|
|
|
SnapshotList* list_; // just for sanity checks
|
|
};
|
|
|
|
class SnapshotList {
|
|
public:
|
|
SnapshotList() {
|
|
list_.prev_ = &list_;
|
|
list_.next_ = &list_;
|
|
list_.number_ = 0xFFFFFFFFL; // placeholder marker, for debugging
|
|
}
|
|
|
|
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) {
|
|
SnapshotImpl* s = new SnapshotImpl;
|
|
s->number_ = seq;
|
|
s->list_ = this;
|
|
s->next_ = &list_;
|
|
s->prev_ = list_.prev_;
|
|
s->prev_->next_ = s;
|
|
s->next_->prev_ = s;
|
|
return s;
|
|
}
|
|
|
|
void Delete(const SnapshotImpl* s) {
|
|
assert(s->list_ == this);
|
|
s->prev_->next_ = s->next_;
|
|
s->next_->prev_ = s->prev_;
|
|
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
|
|
const SequenceNumber GetNewest() {
|
|
if (empty()) {
|
|
return 0;
|
|
}
|
|
return newest()->number_;
|
|
}
|
|
|
|
private:
|
|
// Dummy head of doubly-linked list of snapshots
|
|
SnapshotImpl list_;
|
|
};
|
|
|
|
} // namespace leveldb
|
|
|
|
#endif // STORAGE_LEVELDB_DB_SNAPSHOT_H_
|