mirror of
https://github.com/facebook/rocksdb.git
synced 2024-11-27 11:43:49 +00:00
85 lines
2.4 KiB
C++
85 lines
2.4 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
|
|
|
|
#ifndef ROCKSDB_LITE
|
|
|
|
#include <mutex>
|
|
#include <queue>
|
|
#include <string>
|
|
#include <vector>
|
|
|
|
#include "db/column_family.h"
|
|
#include "rocksdb/db.h"
|
|
#include "rocksdb/iterator.h"
|
|
#include "rocksdb/options.h"
|
|
#include "util/arena.h"
|
|
|
|
namespace rocksdb {
|
|
|
|
class DBImpl;
|
|
struct SuperVersion;
|
|
class ColumnFamilyData;
|
|
|
|
/**
|
|
* ManagedIterator is a special type of iterator that supports freeing the
|
|
* underlying iterator and still being able to access the current key/value
|
|
* pair. This is done by copying the key/value pair so that clients can
|
|
* continue to access the data without getting a SIGSEGV.
|
|
* The underlying iterator can be freed manually through the call to
|
|
* ReleaseIter or automatically (as needed on space pressure or age.)
|
|
* The iterator is recreated using the saved original arguments.
|
|
*/
|
|
class ManagedIterator : public Iterator {
|
|
public:
|
|
ManagedIterator(DBImpl* db, const ReadOptions& read_options,
|
|
ColumnFamilyData* cfd);
|
|
virtual ~ManagedIterator();
|
|
|
|
virtual void SeekToLast() override;
|
|
virtual void Prev() override;
|
|
virtual bool Valid() const override;
|
|
void SeekToFirst() override;
|
|
virtual void Seek(const Slice& target) override;
|
|
virtual void Next() override;
|
|
virtual Slice key() const override;
|
|
virtual Slice value() const override;
|
|
virtual Status status() const override;
|
|
void ReleaseIter(bool only_old);
|
|
void SetDropOld(bool only_old) {
|
|
only_drop_old_ = read_options_.tailing || only_old;
|
|
}
|
|
|
|
private:
|
|
void RebuildIterator();
|
|
void UpdateCurrent();
|
|
void SeekInternal(const Slice& user_key, bool seek_to_first);
|
|
bool NeedToRebuild();
|
|
void Lock();
|
|
bool TryLock();
|
|
void UnLock();
|
|
DBImpl* const db_;
|
|
ReadOptions read_options_;
|
|
ColumnFamilyData* const cfd_;
|
|
ColumnFamilyHandleInternal cfh_;
|
|
|
|
uint64_t svnum_;
|
|
std::unique_ptr<Iterator> mutable_iter_;
|
|
// internal iterator status
|
|
Status status_;
|
|
bool valid_;
|
|
|
|
IterKey cached_key_;
|
|
IterKey cached_value_;
|
|
|
|
bool only_drop_old_ = true;
|
|
bool snapshot_created_;
|
|
bool release_supported_;
|
|
std::mutex in_use_; // is managed iterator in use
|
|
};
|
|
|
|
} // namespace rocksdb
|
|
#endif // !ROCKSDB_LITE
|