ivanallen commented on code in PR #3062: URL: https://github.com/apache/brpc/pull/3062#discussion_r2278149752
########## src/butil/single_iobuf.cpp: ########## @@ -0,0 +1,279 @@ +// 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 + +#include "butil/logging.h" // CHECK, LOG +#include "butil/iobuf.h" +#include "butil/iobuf_inl.h" +#include "butil/single_iobuf.h" + +namespace butil { + +SingleIOBuf::SingleIOBuf() + : _cur_block(NULL) + , _block_size(0) { + _cur_ref.offset = 0; + _cur_ref.length = 0; + _cur_ref.block = NULL; +} + +SingleIOBuf::SingleIOBuf(const IOBuf::BlockRef& ref) { + _cur_block = NULL; + _block_size = 0; + if (ref.block) { + _cur_ref = ref; + _cur_ref.block->inc_ref(); + } +} + +SingleIOBuf::SingleIOBuf(const SingleIOBuf& other) { + _cur_block = NULL; + _block_size = 0; + if (other._cur_ref.block != NULL) { + _cur_ref = other._cur_ref; + _cur_ref.block->inc_ref(); + } +} + +SingleIOBuf::~SingleIOBuf() { + reset(); +} + +SingleIOBuf& SingleIOBuf::operator=(const SingleIOBuf& rhs) { + reset(); + _block_size = 0; + if (rhs._cur_ref.block != NULL) { + _cur_ref = rhs._cur_ref; + _cur_ref.block->inc_ref(); + } + return *this; +} + +void SingleIOBuf::swap(SingleIOBuf& other) { + IOBuf::BlockRef tmp_ref = _cur_ref; + _cur_ref = other._cur_ref; + other._cur_ref = tmp_ref; + IOBuf::Block* tmp_ptr = other._cur_block; + other._cur_block = _cur_block; + _cur_block = tmp_ptr; + uint32_t tmp_size = other._block_size; + other._block_size = _block_size; + _block_size = tmp_size; +} + +void* SingleIOBuf::allocate(uint32_t size) { + IOBuf::Block* b = alloc_block_by_size(size); + if (!b) { + return NULL; + } + _cur_ref.offset = b->size; + _cur_ref.length = size; + _cur_ref.block = b; + b->size += size; + b->inc_ref(); + return b->data + _cur_ref.offset; +} + +void SingleIOBuf::deallocate(void* p) { + if (_cur_ref.block) { + if (_cur_ref.block->data + _cur_ref.offset == (char*)p) { + reset(); + } + } +} + +IOBuf::Block* SingleIOBuf::alloc_block_by_size(uint32_t data_size) { + if (_cur_block != NULL) { + if (_cur_block->left_space() >= data_size) { + return _cur_block; + } else { + _cur_block->dec_ref(); + _cur_block = NULL; + } + } + uint32_t total_size = data_size + sizeof(IOBuf::Block); + if (total_size <= IOBuf::DEFAULT_BLOCK_SIZE) { + _cur_block = iobuf::acquire_tls_block(); + if (_cur_block != NULL) { + if (_cur_block->left_space() >= data_size) { + return _cur_block; + } else { + _cur_block->dec_ref(); + _cur_block = NULL; + } + } + _cur_block = iobuf::create_block(); + } else { + _cur_block = iobuf::create_block(total_size); + _block_size = total_size; + } + if (BAIDU_UNLIKELY(!_cur_block)) { + errno = ENOMEM; + _block_size = 0; + return NULL; + } + return _cur_block; +} + +void SingleIOBuf::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) { + memcpy((u_char*)new_p + new_size - in_use_back, (u_char*)old_p + old_size - in_use_back, + in_use_back); + memcpy(new_p, old_p, in_use_front); +} + +void* SingleIOBuf::reallocate_downward(uint32_t new_size, uint32_t in_use_back, + uint32_t in_use_front) { + IOBuf::BlockRef& ref = _cur_ref; + if (BAIDU_UNLIKELY(new_size <= ref.length)) { + LOG(ERROR) << "invalid new size:" << new_size; + errno = EINVAL; + return NULL; + } + if (BAIDU_UNLIKELY(ref.block == NULL)) { + LOG(ERROR) << "SingleIOBuf reallocate_downward failed. Block cannot be null!"; + errno = EINVAL; + return NULL; + } + char* old_p = ref.block->data + ref.offset; + uint32_t old_size = ref.length; + IOBuf::Block* b = alloc_block_by_size(new_size); + if (!b) { + return NULL; + } + char* new_p = b->data + b->size; + memcpy_downward(old_p, old_size, + new_p, new_size, + in_use_back, in_use_front); + ref.block->dec_ref(); + _cur_ref.offset = b->size; + _cur_ref.length = new_size; + _cur_ref.block = b; + b->size += new_size; + b->inc_ref(); + return new_p; +} + +const void* SingleIOBuf::get_begin() const { + if (_cur_ref.block) { + return _cur_ref.block->data + _cur_ref.offset; + } + return NULL; +} + +uint32_t SingleIOBuf::get_length() const { + return _cur_ref.length; +} + +void SingleIOBuf::reset() { + if (_cur_block) { + if (_block_size == 0) { + iobuf::release_tls_block(_cur_block); + } else { + _cur_block->dec_ref(); + _block_size = 0; + } + _cur_block = NULL; + } + if (_cur_ref.block != NULL) { + _cur_ref.block->dec_ref(); + } + _cur_ref.offset = 0; + _cur_ref.length = 0; + _cur_ref.block = NULL; +} + +bool SingleIOBuf::assign(const IOBuf& buf, uint32_t msg_size) { + if (BAIDU_UNLIKELY(buf.length() < msg_size)) { + LOG(ERROR) << "Fail to dump_mult_iobuf msg_size:" << msg_size + << " from source iobuf of size:" << buf.length(); + return false; + } + reset(); + if (BAIDU_UNLIKELY(msg_size == 0)) { + return true; + } + const IOBuf::BlockRef& ref = buf._front_ref(); + if (ref.length >= msg_size) { + _cur_ref.offset = ref.offset; + _cur_ref.length = msg_size; + _cur_ref.block = ref.block; + _cur_ref.block->inc_ref(); + return true; + } else { + IOBuf::Block* b = alloc_block_by_size(msg_size); + if (!b) { + return false; + } + char* out = b->data + b->size; + const size_t nref = buf.backing_block_num(); + uint32_t last_len = msg_size; + for (size_t i = 0; i < nref && last_len > 0; ++i) { + const IOBuf::BlockRef& r = buf._ref_at(i); + uint32_t n = std::min(r.length, last_len); + iobuf::cp(out, r.block->data + r.offset, n); + last_len -= n; + out += n; + } + _cur_ref.offset = b->size; + _cur_ref.length = msg_size; + _cur_ref.block = b; + b->size += msg_size; + _cur_ref.block->inc_ref(); + return true; + } +} + +void SingleIOBuf::append_to(IOBuf* buf) const { + if (buf && _cur_ref.block) { + buf->_push_back_ref(_cur_ref); + } +} + +int SingleIOBuf::assign_user_data(void* data, size_t size, void (*deleter)(void*)) { + reset(); + if (size > 0xFFFFFFFFULL - 100) { Review Comment: What is the exact meaning of 100? Does it refer to the reserved area of in_use_back? -- 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
