rocksdb/table/merger.h
Aaron Gao 2482d5fb45 support Prev() in prefix seek mode
Summary: As title, make sure Prev() works as expected with Next() when the current iter->key() in the range of the same prefix in prefix seek mode

Test Plan: make all check -j64 (add prefix_test with PrefixSeekModePrev test case)

Reviewers: andrewkr, sdong, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: yoshinorim, andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D61419
2016-08-29 20:55:39 -07:00

65 lines
2.1 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.
//
// 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/slice_transform.h"
#include "rocksdb/types.h"
namespace rocksdb {
class Comparator;
class InternalIterator;
class Env;
class Arena;
// Return an iterator that provided the union of the data in
// children[0,n-1]. Takes ownership of the child iterators and
// will delete them when the result iterator is deleted.
//
// The result does no duplicate suppression. I.e., if a particular
// key is present in K child iterators, it will be yielded K times.
//
// REQUIRES: n >= 0
extern InternalIterator* NewMergingIterator(
const Comparator* comparator, InternalIterator** children, int n,
Arena* arena = nullptr,
const SliceTransform* const prefix_extractor = nullptr);
class MergingIterator;
// A builder class to build a merging iterator by adding iterators one by one.
class MergeIteratorBuilder {
public:
// comparator: the comparator used in merging comparator
// arena: where the merging iterator needs to be allocated from.
explicit MergeIteratorBuilder(
const Comparator* comparator, Arena* arena,
const SliceTransform* const prefix_extractor = nullptr);
~MergeIteratorBuilder() {}
// Add iter to the merging iterator.
void AddIterator(InternalIterator* iter);
// Get arena used to build the merging iterator. It is called one a child
// iterator needs to be allocated.
Arena* GetArena() { return arena; }
// Return the result merging iterator.
InternalIterator* Finish();
private:
MergingIterator* merge_iter;
InternalIterator* first_iter;
bool use_merging_iter;
Arena* arena;
};
} // namespace rocksdb