ba64a4cf52
Summary:
This reverts commit f3a7847598.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5440
Differential Revision: D15765967
Pulled By: ltamasi
fbshipit-source-id: d027fe24132e3729289cd7c01857a7eb449d9dd0
121 lines
3.3 KiB
C++
121 lines
3.3 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 <set>
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#include "table/internal_iterator.h"
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namespace rocksdb {
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// A internal wrapper class with an interface similar to Iterator that caches
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// the valid() and key() results for an underlying iterator.
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// This can help avoid virtual function calls and also gives better
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// cache locality.
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template <class TValue = Slice>
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class IteratorWrapperBase {
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public:
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IteratorWrapperBase() : iter_(nullptr), valid_(false) {}
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explicit IteratorWrapperBase(InternalIteratorBase<TValue>* _iter)
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: iter_(nullptr) {
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Set(_iter);
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}
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~IteratorWrapperBase() {}
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InternalIteratorBase<TValue>* iter() const { return iter_; }
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// Set the underlying Iterator to _iter and return
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// previous underlying Iterator.
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InternalIteratorBase<TValue>* Set(InternalIteratorBase<TValue>* _iter) {
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InternalIteratorBase<TValue>* old_iter = iter_;
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iter_ = _iter;
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if (iter_ == nullptr) {
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valid_ = false;
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} else {
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Update();
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}
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return old_iter;
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}
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void DeleteIter(bool is_arena_mode) {
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if (iter_) {
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if (!is_arena_mode) {
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delete iter_;
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} else {
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iter_->~InternalIteratorBase<TValue>();
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}
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}
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}
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// Iterator interface methods
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bool Valid() const { return valid_; }
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Slice key() const { assert(Valid()); return key_; }
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TValue value() const {
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assert(Valid());
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return iter_->value();
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}
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// Methods below require iter() != nullptr
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Status status() const { assert(iter_); return iter_->status(); }
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void Next() {
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assert(iter_);
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valid_ = iter_->NextAndGetResult(&key_);
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assert(!valid_ || iter_->status().ok());
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}
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void Prev() { assert(iter_); iter_->Prev(); Update(); }
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void Seek(const Slice& k) {
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TEST_SYNC_POINT("IteratorWrapper::Seek:0");
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assert(iter_);
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iter_->Seek(k);
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Update();
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}
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void SeekForPrev(const Slice& k) {
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assert(iter_);
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iter_->SeekForPrev(k);
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Update();
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}
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void SeekToFirst() { assert(iter_); iter_->SeekToFirst(); Update(); }
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void SeekToLast() { assert(iter_); iter_->SeekToLast(); Update(); }
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void SetPinnedItersMgr(PinnedIteratorsManager* pinned_iters_mgr) {
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assert(iter_);
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iter_->SetPinnedItersMgr(pinned_iters_mgr);
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}
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bool IsKeyPinned() const {
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assert(Valid());
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return iter_->IsKeyPinned();
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}
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bool IsValuePinned() const {
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assert(Valid());
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return iter_->IsValuePinned();
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}
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private:
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void Update() {
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valid_ = iter_->Valid();
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if (valid_) {
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key_ = iter_->key();
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assert(iter_->status().ok());
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}
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}
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InternalIteratorBase<TValue>* iter_;
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bool valid_;
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Slice key_;
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};
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using IteratorWrapper = IteratorWrapperBase<Slice>;
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class Arena;
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// Return an empty iterator (yields nothing) allocated from arena.
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template <class TValue = Slice>
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extern InternalIteratorBase<TValue>* NewEmptyInternalIterator(Arena* arena);
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} // namespace rocksdb
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