yanglimingcn commented on code in PR #3062: URL: https://github.com/apache/brpc/pull/3062#discussion_r2278080714
########## src/butil/single_iobuf.h: ########## @@ -0,0 +1,107 @@ +// 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. + +// SingleIOBuf - A continuous zero-copied buffer + +#ifndef BUTIL_SINGLE_IOBUF_H +#define BUTIL_SINGLE_IOBUF_H + +#include "butil/iobuf.h" +#include "butil/iobuf_inl.h" + +namespace butil { + +// SingleIOBuf is a lightweight buffer that manages a single IOBuf::Block. +// It always ensures that the underlying memory is contiguous and +// avoids unnecessary memory copies. +// It is primarily used to efficiently serialize and deserialize +// RPC requests in flatbuffers. +class SingleIOBuf { +public: + SingleIOBuf(); + ~SingleIOBuf(); + SingleIOBuf(const IOBuf::BlockRef& ref); + SingleIOBuf(const SingleIOBuf& other); + SingleIOBuf& operator=(const SingleIOBuf& rhs); + void swap(SingleIOBuf& other); + + // Allocates a contiguous memory region of the specified size. + // Returns a pointer to the start of allocated space within the block. + void* allocate(uint32_t size); + // Deallocates the block if the given pointer matches its starting address. + void deallocate(void* p); + + // Reallocates the current buffer to a larger size. + void* reallocate_downward(uint32_t new_size, + uint32_t in_use_back, + uint32_t in_use_front); + + // Returns a pointer to the beginning of the current buffer data. + const void* get_begin() const; + + // Get the length of the SingleIOBuf. + uint32_t get_length() const; + + // Reset the SingleIOBuf by release the block and clear the BlockRef. + void reset(); + + // Assigns data from the given IOBuf to this SingleIOBuf. + // If the source contains multiple BlockRef segments, + // they will be concatenated into a single contiguous block. + bool assign(const IOBuf& buf, uint32_t msg_size); + + // Appends the current block of the SingleIOBuf to the given IOBuf. + void append_to(IOBuf* buf) const; + + const IOBuf::BlockRef& get_cur_ref() const { return _cur_ref; } + void* get_cur_block() { return (void*)_cur_ref.block; } + + // Returns the number of underlying blocks in the SingleIOBuf, + // which is either 1 if a block exists or 0 if none. + size_t backing_block_num() const { return _cur_ref.block != NULL ? 1 : 0; } + + // Assigns user date to the SingleIOBuf, + // updates _cur_ref to point to the block storing the data. + int assign_user_data(void* data, size_t size, void (*deleter)(void*)); + + // Increments the reference count of the specified target block. + static void target_block_inc_ref(void* b); + // Decrements the reference count of the specified target block. + static void target_block_dec_ref(void* b); + +protected: + // Copy from the old buffer to the corresponding positions in the new block. + void memcpy_downward(void* old_p, uint32_t old_size, + void* new_p, uint32_t new_size, + uint32_t in_use_back, uint32_t in_use_front); + + // Allocates and returns a memory block large enough to hold the specified data size, + // reusing an existing block when possible or creating a new one if necessary. + IOBuf::Block* alloc_block_by_size(uint32_t data_size); + +private: + // Current block the SingleIOBuf used. Review Comment: is this only one block in SingleIOBuf？ -- 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: dev-unsubscr...@brpc.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@brpc.apache.org For additional commands, e-mail: dev-h...@brpc.apache.org
