| // Copyright (c) 2011-present, Facebook, Inc. All rights reserved. |
| // This source code is licensed under both the GPLv2 (found in the |
| // COPYING file in the root directory) and Apache 2.0 License |
| // (found in the LICENSE.Apache file in the root directory). |
| // |
| // Copyright (c) 2011 The LevelDB Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. See the AUTHORS file for names of contributors. |
| |
| #pragma once |
| |
| #include <set> |
| |
| #include "table/internal_iterator.h" |
| |
| namespace rocksdb { |
| |
| // A internal wrapper class with an interface similar to Iterator that caches |
| // the valid() and key() results for an underlying iterator. |
| // This can help avoid virtual function calls and also gives better |
| // cache locality. |
| class IteratorWrapper { |
| public: |
| IteratorWrapper() : iter_(nullptr), valid_(false) {} |
| explicit IteratorWrapper(InternalIterator* _iter) : iter_(nullptr) { |
| Set(_iter); |
| } |
| ~IteratorWrapper() {} |
| InternalIterator* iter() const { return iter_; } |
| |
| // Set the underlying Iterator to _iter and return |
| // previous underlying Iterator. |
| InternalIterator* Set(InternalIterator* _iter) { |
| InternalIterator* old_iter = iter_; |
| |
| iter_ = _iter; |
| if (iter_ == nullptr) { |
| valid_ = false; |
| } else { |
| Update(); |
| } |
| return old_iter; |
| } |
| |
| void DeleteIter(bool is_arena_mode) { |
| if (iter_) { |
| if (!is_arena_mode) { |
| delete iter_; |
| } else { |
| iter_->~InternalIterator(); |
| } |
| } |
| } |
| |
| // Iterator interface methods |
| bool Valid() const { return valid_; } |
| Slice key() const { assert(Valid()); return key_; } |
| Slice value() const { assert(Valid()); return iter_->value(); } |
| // Methods below require iter() != nullptr |
| Status status() const { assert(iter_); return iter_->status(); } |
| void Next() { assert(iter_); iter_->Next(); Update(); } |
| void Prev() { assert(iter_); iter_->Prev(); Update(); } |
| void Seek(const Slice& k) { assert(iter_); iter_->Seek(k); Update(); } |
| void SeekForPrev(const Slice& k) { |
| assert(iter_); |
| iter_->SeekForPrev(k); |
| Update(); |
| } |
| void SeekToFirst() { assert(iter_); iter_->SeekToFirst(); Update(); } |
| void SeekToLast() { assert(iter_); iter_->SeekToLast(); Update(); } |
| |
| void SetPinnedItersMgr(PinnedIteratorsManager* pinned_iters_mgr) { |
| assert(iter_); |
| iter_->SetPinnedItersMgr(pinned_iters_mgr); |
| } |
| bool IsKeyPinned() const { |
| assert(Valid()); |
| return iter_->IsKeyPinned(); |
| } |
| bool IsValuePinned() const { |
| assert(Valid()); |
| return iter_->IsValuePinned(); |
| } |
| |
| private: |
| void Update() { |
| valid_ = iter_->Valid(); |
| if (valid_) { |
| key_ = iter_->key(); |
| } |
| } |
| |
| InternalIterator* iter_; |
| bool valid_; |
| Slice key_; |
| }; |
| |
| class Arena; |
| // Return an empty iterator (yields nothing) allocated from arena. |
| extern InternalIterator* NewEmptyInternalIterator(Arena* arena); |
| |
| // Return an empty iterator with the specified status, allocated arena. |
| extern InternalIterator* NewErrorInternalIterator(const Status& status, |
| Arena* arena); |
| |
| } // namespace rocksdb |