992dfc7811
Summary: In long scans, virtual function calls of Next(), Valid(), key() and value() are not trivial. By introducing NextAndGetResult(), Some of the Next(), Valid() and key() calls are consolidated into one virtual function call to reduce CPU. Also did some inline tricks and add some "final" randomly in some functions. Even without the "final" annotation, most Next() calls are inlined with -O3, but sometimes with a final it is inlined by O2 too. It doesn't hurt to add those final annotations. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5197 Differential Revision: D14945977 Pulled By: siying fbshipit-source-id: 7003969f9a5f1d5717f0bda503b91d19ba75ed88
116 lines
3.3 KiB
C++
116 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) { assert(iter_); iter_->Seek(k); Update(); }
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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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