Revision 926f3a78a64b327475ee6c60b6c8ab4f34253204 authored by Siying Dong on 09 July 2018, 22:17:38 UTC, committed by Facebook Github Bot on 09 July 2018, 22:28:12 UTC
Summary: Right now slow deletion with ftruncate doesn't work well with checkpoints because it ruin hard linked files in checkpoints. To fix it, check the file has no other hard link before ftruncate it. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4093 Differential Revision: D8730360 Pulled By: siying fbshipit-source-id: 756eea5bce8a87b9a2ea3a5bfa190b2cab6f75df
1 parent b984637
merging_iterator.h
// 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).
//
// 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 "db/dbformat.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 InternalKeyComparator* comparator, InternalIterator** children, int n,
Arena* arena = nullptr, bool prefix_seek_mode = false);
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 InternalKeyComparator* comparator,
Arena* arena, bool prefix_seek_mode = false);
~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
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