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35ad531be3
Summary: Separate a new class InternalIterator from class Iterator, when the look-up is done internally, which also means they operate on key with sequence ID and type. This change will enable potential future optimizations but for now InternalIterator's functions are still the same as Iterator's. At the same time, separate the cleanup function to a separate class and let both of InternalIterator and Iterator inherit from it. Test Plan: Run all existing tests. Reviewers: igor, yhchiang, anthony, kradhakrishnan, IslamAbdelRahman, rven Reviewed By: rven Subscribers: leveldb, dhruba Differential Revision: https://reviews.facebook.net/D48549
83 lines
2.7 KiB
C++
83 lines
2.7 KiB
C++
// Copyright (c) 2013, 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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//
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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 "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
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// caches 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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class IteratorWrapper {
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public:
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IteratorWrapper(): iter_(nullptr), valid_(false) { }
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explicit IteratorWrapper(InternalIterator* _iter) : iter_(nullptr) {
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Set(_iter);
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}
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~IteratorWrapper() {}
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InternalIterator* iter() const { return iter_; }
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// Takes ownership of "iter" and will delete it when destroyed, or
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// when Set() is invoked again.
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void Set(InternalIterator* _iter) {
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delete 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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}
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void DeleteIter(bool is_arena_mode) {
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if (!is_arena_mode) {
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delete iter_;
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} else {
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iter_->~InternalIterator();
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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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Slice value() const { assert(Valid()); return iter_->value(); }
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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() { assert(iter_); iter_->Next(); Update(); }
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void Prev() { assert(iter_); iter_->Prev(); Update(); }
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void Seek(const Slice& k) { assert(iter_); iter_->Seek(k); Update(); }
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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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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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}
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}
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InternalIterator* iter_;
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bool valid_;
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Slice key_;
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};
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class Arena;
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// Return an empty iterator (yields nothing) allocated from arena.
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extern InternalIterator* NewEmptyInternalIterator(Arena* arena);
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// Return an empty iterator with the specified status, allocated arena.
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extern InternalIterator* NewErrorInternalIterator(const Status& status,
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Arena* arena);
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} // namespace rocksdb
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