8843129ece
Summary: Move arena, allocator, and memory tools under util to a separate memory/ directory. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5382 Differential Revision: D15564655 Pulled By: siying fbshipit-source-id: 9cd6b5d0d3d52b39606e19221fa154596e5852a5
140 lines
5.6 KiB
C++
140 lines
5.6 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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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 <stdint.h>
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#include <string>
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#include "db/db_impl.h"
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#include "db/dbformat.h"
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#include "db/range_del_aggregator.h"
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#include "memory/arena.h"
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#include "options/cf_options.h"
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#include "rocksdb/db.h"
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#include "rocksdb/iterator.h"
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#include "util/autovector.h"
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namespace rocksdb {
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// This file declares the factory functions of DBIter, in its original form
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// or a wrapped form with class ArenaWrappedDBIter, which is defined here.
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// Class DBIter, which is declared and implemented inside db_iter.cc, is
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// a iterator that converts internal keys (yielded by an InternalIterator)
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// that were live at the specified sequence number into appropriate user
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// keys.
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// Each internal key is consist of a user key, a sequence number, and a value
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// type. DBIter deals with multiple key versions, tombstones, merge operands,
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// etc, and exposes an Iterator.
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// For example, DBIter may wrap following InternalIterator:
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// user key: AAA value: v3 seqno: 100 type: Put
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// user key: AAA value: v2 seqno: 97 type: Put
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// user key: AAA value: v1 seqno: 95 type: Put
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// user key: BBB value: v1 seqno: 90 type: Put
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// user key: BBC value: N/A seqno: 98 type: Delete
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// user key: BBC value: v1 seqno: 95 type: Put
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// If the snapshot passed in is 102, then the DBIter is expected to
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// expose the following iterator:
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// key: AAA value: v3
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// key: BBB value: v1
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// If the snapshot passed in is 96, then it should expose:
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// key: AAA value: v1
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// key: BBB value: v1
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// key: BBC value: v1
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//
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class Arena;
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class DBIter;
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// Return a new iterator that converts internal keys (yielded by
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// "*internal_iter") that were live at the specified `sequence` number
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// into appropriate user keys.
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extern Iterator* NewDBIterator(
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Env* env, const ReadOptions& read_options,
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const ImmutableCFOptions& cf_options,
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const MutableCFOptions& mutable_cf_options,
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const Comparator* user_key_comparator, InternalIterator* internal_iter,
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const SequenceNumber& sequence, uint64_t max_sequential_skip_in_iterations,
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ReadCallback* read_callback, DBImpl* db_impl = nullptr,
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ColumnFamilyData* cfd = nullptr, bool allow_blob = false);
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// A wrapper iterator which wraps DB Iterator and the arena, with which the DB
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// iterator is supposed be allocated. This class is used as an entry point of
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// a iterator hierarchy whose memory can be allocated inline. In that way,
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// accessing the iterator tree can be more cache friendly. It is also faster
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// to allocate.
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// When using the class's Iterator interface, the behavior is exactly
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// the same as the inner DBIter.
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class ArenaWrappedDBIter : public Iterator {
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public:
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virtual ~ArenaWrappedDBIter();
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// Get the arena to be used to allocate memory for DBIter to be wrapped,
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// as well as child iterators in it.
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virtual Arena* GetArena() { return &arena_; }
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virtual ReadRangeDelAggregator* GetRangeDelAggregator();
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// Set the internal iterator wrapped inside the DB Iterator. Usually it is
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// a merging iterator.
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virtual void SetIterUnderDBIter(InternalIterator* iter);
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virtual bool Valid() const override;
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virtual void SeekToFirst() override;
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virtual void SeekToLast() override;
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virtual void Seek(const Slice& target) override;
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virtual void SeekForPrev(const Slice& target) override;
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virtual void Next() override;
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virtual void Prev() override;
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virtual Slice key() const override;
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virtual Slice value() const override;
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virtual Status status() const override;
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virtual Status Refresh() override;
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bool IsBlob() const;
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virtual Status GetProperty(std::string prop_name, std::string* prop) override;
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void Init(Env* env, const ReadOptions& read_options,
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const ImmutableCFOptions& cf_options,
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const MutableCFOptions& mutable_cf_options,
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const SequenceNumber& sequence,
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uint64_t max_sequential_skip_in_iterations, uint64_t version_number,
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ReadCallback* read_callback, DBImpl* db_impl, ColumnFamilyData* cfd,
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bool allow_blob, bool allow_refresh);
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void StoreRefreshInfo(const ReadOptions& read_options, DBImpl* db_impl,
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ColumnFamilyData* cfd, ReadCallback* read_callback,
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bool allow_blob) {
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read_options_ = read_options;
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db_impl_ = db_impl;
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cfd_ = cfd;
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read_callback_ = read_callback;
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allow_blob_ = allow_blob;
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}
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private:
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DBIter* db_iter_;
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Arena arena_;
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uint64_t sv_number_;
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ColumnFamilyData* cfd_ = nullptr;
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DBImpl* db_impl_ = nullptr;
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ReadOptions read_options_;
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ReadCallback* read_callback_;
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bool allow_blob_ = false;
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bool allow_refresh_ = true;
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};
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// Generate the arena wrapped iterator class.
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// `db_impl` and `cfd` are used for reneweal. If left null, renewal will not
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// be supported.
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extern ArenaWrappedDBIter* NewArenaWrappedDbIterator(
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Env* env, const ReadOptions& read_options,
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const ImmutableCFOptions& cf_options,
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const MutableCFOptions& mutable_cf_options, const SequenceNumber& sequence,
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uint64_t max_sequential_skip_in_iterations, uint64_t version_number,
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ReadCallback* read_callback, DBImpl* db_impl = nullptr,
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ColumnFamilyData* cfd = nullptr, bool allow_blob = false,
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bool allow_refresh = true);
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} // namespace rocksdb
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