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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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// This source code is also licensed under the GPLv2 license found in the
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// COPYING file in the root directory of this source tree.
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#pragma once
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#include "rocksdb/iterator.h"
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#include "rocksdb/env.h"
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#include "table/iterator_wrapper.h"
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namespace rocksdb {
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struct ReadOptions;
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class InternalKeyComparator;
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In DB::NewIterator(), try to allocate the whole iterator tree in an arena
Summary:
In this patch, try to allocate the whole iterator tree starting from DBIter from an arena
1. ArenaWrappedDBIter is created when serves as the entry point of an iterator tree, with an arena in it.
2. Add an option to create iterator from arena for following iterators: DBIter, MergingIterator, MemtableIterator, all mem table's iterators, all table reader's iterators and two level iterator.
3. MergeIteratorBuilder is created to incrementally build the tree of internal iterators. It is passed to mem table list and version set and add iterators to it.
Limitations:
(1) Only DB::NewIterator() without tailing uses the arena. Other cases, including readonly DB and compactions are still from malloc
(2) Two level iterator itself is allocated in arena, but not iterators inside it.
Test Plan: make all check
Reviewers: ljin, haobo
Reviewed By: haobo
Subscribers: leveldb, dhruba, yhchiang, igor
Differential Revision: https://reviews.facebook.net/D18513
11 years ago
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class Arena;
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struct TwoLevelIteratorState {
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explicit TwoLevelIteratorState(bool _check_prefix_may_match)
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: check_prefix_may_match(_check_prefix_may_match) {}
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virtual ~TwoLevelIteratorState() {}
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virtual InternalIterator* NewSecondaryIterator(const Slice& handle) = 0;
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virtual bool PrefixMayMatch(const Slice& internal_key) = 0;
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// If call PrefixMayMatch()
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bool check_prefix_may_match;
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};
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// Return a new two level iterator. A two-level iterator contains an
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// index iterator whose values point to a sequence of blocks where
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// each block is itself a sequence of key,value pairs. The returned
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// two-level iterator yields the concatenation of all key/value pairs
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// in the sequence of blocks. Takes ownership of "index_iter" and
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// will delete it when no longer needed.
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//
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// Uses a supplied function to convert an index_iter value into
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// an iterator over the contents of the corresponding block.
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In DB::NewIterator(), try to allocate the whole iterator tree in an arena
Summary:
In this patch, try to allocate the whole iterator tree starting from DBIter from an arena
1. ArenaWrappedDBIter is created when serves as the entry point of an iterator tree, with an arena in it.
2. Add an option to create iterator from arena for following iterators: DBIter, MergingIterator, MemtableIterator, all mem table's iterators, all table reader's iterators and two level iterator.
3. MergeIteratorBuilder is created to incrementally build the tree of internal iterators. It is passed to mem table list and version set and add iterators to it.
Limitations:
(1) Only DB::NewIterator() without tailing uses the arena. Other cases, including readonly DB and compactions are still from malloc
(2) Two level iterator itself is allocated in arena, but not iterators inside it.
Test Plan: make all check
Reviewers: ljin, haobo
Reviewed By: haobo
Subscribers: leveldb, dhruba, yhchiang, igor
Differential Revision: https://reviews.facebook.net/D18513
11 years ago
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// arena: If not null, the arena is used to allocate the Iterator.
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// When destroying the iterator, the destructor will destroy
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// all the states but those allocated in arena.
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// need_free_iter_and_state: free `state` and `first_level_iter` if
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// true. Otherwise, just call destructor.
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extern InternalIterator* NewTwoLevelIterator(
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TwoLevelIteratorState* state, InternalIterator* first_level_iter,
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Arena* arena = nullptr, bool need_free_iter_and_state = true);
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} // namespace rocksdb
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