| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you under the Apache License, Version 2.0 (the |
| // "License"); you may not use this file except in compliance |
| // with the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License. |
| |
| #ifndef KUDU_CFILE_BLOCK_HANDLE_H |
| #define KUDU_CFILE_BLOCK_HANDLE_H |
| |
| #include "kudu/cfile/block_cache.h" |
| |
| namespace kudu { |
| |
| namespace cfile { |
| |
| // When blocks are read, they are sometimes resident in the block cache, and sometimes skip the |
| // block cache. In the case that they came from the cache, we just need to dereference them when |
| // they stop being used. In the case that they didn't come from cache, we need to actually free |
| // the underlying data. |
| class BlockHandle { |
| public: |
| static BlockHandle WithOwnedData(const Slice& data) { |
| return BlockHandle(data); |
| } |
| |
| static BlockHandle WithDataFromCache(BlockCacheHandle *handle) { |
| return BlockHandle(handle); |
| } |
| |
| // Constructor to use to Pass to. |
| BlockHandle() |
| : is_data_owner_(false) { } |
| |
| // Move constructor and assignment |
| BlockHandle(BlockHandle&& other) noexcept { |
| TakeState(&other); |
| } |
| BlockHandle& operator=(BlockHandle&& other) noexcept { |
| TakeState(&other); |
| return *this; |
| } |
| |
| ~BlockHandle() { |
| Reset(); |
| } |
| |
| Slice data() const { |
| if (is_data_owner_) { |
| return data_; |
| } else { |
| return dblk_data_.data(); |
| } |
| } |
| |
| private: |
| BlockCacheHandle dblk_data_; |
| Slice data_; |
| bool is_data_owner_; |
| |
| explicit BlockHandle(Slice data) |
| : data_(data), |
| is_data_owner_(true) { |
| } |
| |
| explicit BlockHandle(BlockCacheHandle *dblk_data) |
| : is_data_owner_(false) { |
| dblk_data_.swap(dblk_data); |
| } |
| |
| void TakeState(BlockHandle* other) { |
| Reset(); |
| |
| is_data_owner_ = other->is_data_owner_; |
| if (is_data_owner_) { |
| data_ = other->data_; |
| other->is_data_owner_ = false; |
| } else { |
| dblk_data_.swap(&other->dblk_data_); |
| } |
| } |
| |
| void Reset() { |
| if (is_data_owner_) { |
| delete [] data_.data(); |
| is_data_owner_ = false; |
| } |
| data_ = ""; |
| } |
| |
| DISALLOW_COPY_AND_ASSIGN(BlockHandle); |
| }; |
| |
| } // namespace cfile |
| } // namespace kudu |
| #endif |