coderex2522 commented on code in PR #1271: URL: https://github.com/apache/orc/pull/1271#discussion_r990740765
########## c++/src/BlockBuffer.hh: ########## @@ -0,0 +1,108 @@ +/** + * 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 ORC_MEMORYPOOL_IMPL_HH +#define ORC_MEMORYPOOL_IMPL_HH + +#include "orc/MemoryPool.hh" + +#include <vector> + +namespace orc { + + /** + * Block points to a section of memory allocated by BlockBuffer, + * containing the corresponding physical memory address and size. + */ + struct Block { + char* data; + uint64_t size; + + Block() : data(nullptr), size(0) {} + Block(char* _data, uint64_t _size) : data(_data), size(_size) {} + Block(const Block& block) = default; + ~Block() = default; + }; + + /** + * BlockBuffer implements a memory allocation policy based on + * equal-length blocks. BlockBuffer will reserve multiple blocks + * for allocation. + */ + class BlockBuffer { + private: + MemoryPool& memoryPool; + // current buffer size + uint64_t currentSize; + // maximal capacity (actual allocated memory) + uint64_t currentCapacity; + // unit for buffer expansion + const uint64_t blockSize; + // pointers to the start of each block + std::vector<char*> blocks; + + // non-copy-constructible + BlockBuffer(BlockBuffer& buffer) = delete; + BlockBuffer& operator=(BlockBuffer& buffer) = delete; + BlockBuffer(BlockBuffer&& buffer) = delete; + BlockBuffer& operator=(BlockBuffer&& buffer) = delete; + + public: + BlockBuffer(MemoryPool& pool, uint64_t blockSize); + + ~BlockBuffer(); + + /** + * Get the allocated block object. + * The last allocated block size may be less than blockSize, + * and the rest of the blocks are all of size blockSize. + * @param blockIndex the index of blocks + * @return the allocated block object + */ + Block getBlock(uint64_t blockIndex) const; + + /** + * Get a empty block or a new block if the buffer is exhausted. + * If the last allocated block size is less than blockSize, + * the empty block size is blockSize - lastBlockSize. + * Otherwise, the empty block size is blockSize. + * @return a empty block object + */ + Block getEmptyBlock(); + + /** + * Get the number of allocated blocks + */ + uint64_t getBlockNumber() const { + return (currentSize + blockSize - 1) / blockSize; + } + + uint64_t size() const { + return currentSize; + } + + uint64_t capacity() const { + return currentCapacity; + } + + void resize(uint64_t size); Review Comment: Class DataBuffer only recycles memory during destructor, so class BlockBuffer does not support shrink function, which can be further optimized later. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
