114 lines
3.4 KiB
C++
114 lines
3.4 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#include "td/utils/buffer.h"
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#include "td/utils/port/thread_local.h"
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#include <cstddef>
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#include <new>
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// fixes https://bugs.llvm.org/show_bug.cgi?id=33723 for clang >= 3.6 + c++11 + libc++
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#if TD_CLANG && _LIBCPP_VERSION
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#define TD_OFFSETOF __builtin_offsetof
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#else
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#define TD_OFFSETOF offsetof
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#endif
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namespace td {
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TD_THREAD_LOCAL BufferAllocator::BufferRawTls *BufferAllocator::buffer_raw_tls; // static zero-initialized
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std::atomic<size_t> BufferAllocator::buffer_mem;
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size_t BufferAllocator::get_buffer_mem() {
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return buffer_mem;
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}
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BufferAllocator::WriterPtr BufferAllocator::create_writer(size_t size) {
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if (size < 512) {
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size = 512;
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}
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return create_writer_exact(size);
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}
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BufferAllocator::WriterPtr BufferAllocator::create_writer_exact(size_t size) {
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return WriterPtr(create_buffer_raw(size));
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}
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BufferAllocator::WriterPtr BufferAllocator::create_writer(size_t size, size_t prepend, size_t append) {
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auto ptr = create_writer(size + prepend + append);
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ptr->begin_ += prepend;
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ptr->end_ += prepend + size;
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return ptr;
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}
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BufferAllocator::ReaderPtr BufferAllocator::create_reader(size_t size) {
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if (size < 512) {
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return create_reader_fast(size);
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}
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auto ptr = create_writer_exact(size);
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ptr->end_ += (size + 7) & -8;
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return create_reader(ptr);
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}
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BufferAllocator::ReaderPtr BufferAllocator::create_reader_fast(size_t size) {
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size = (size + 7) & -8;
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init_thread_local<BufferRawTls>(buffer_raw_tls);
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auto buffer_raw = buffer_raw_tls->buffer_raw.get();
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if (buffer_raw == nullptr || buffer_raw->data_size_ - buffer_raw->end_.load(std::memory_order_relaxed) < size) {
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buffer_raw = create_buffer_raw(4096 * 4);
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buffer_raw_tls->buffer_raw = std::unique_ptr<BufferRaw, BufferAllocator::BufferRawDeleter>(buffer_raw);
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}
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buffer_raw->end_.fetch_add(size, std::memory_order_relaxed);
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buffer_raw->ref_cnt_.fetch_add(1, std::memory_order_acq_rel);
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return ReaderPtr(buffer_raw);
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}
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BufferAllocator::ReaderPtr BufferAllocator::create_reader(const WriterPtr &raw) {
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raw->was_reader_ = true;
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raw->ref_cnt_.fetch_add(1, std::memory_order_acq_rel);
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return ReaderPtr(raw.get());
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}
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BufferAllocator::ReaderPtr BufferAllocator::create_reader(const ReaderPtr &raw) {
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raw->ref_cnt_.fetch_add(1, std::memory_order_acq_rel);
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return ReaderPtr(raw.get());
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}
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void BufferAllocator::dec_ref_cnt(BufferRaw *ptr) {
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int left = ptr->ref_cnt_.fetch_sub(1, std::memory_order_acq_rel);
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if (left == 1) {
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auto buf_size = max(sizeof(BufferRaw), TD_OFFSETOF(BufferRaw, data_) + ptr->data_size_);
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buffer_mem -= buf_size;
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ptr->~BufferRaw();
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delete[] ptr;
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}
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}
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BufferRaw *BufferAllocator::create_buffer_raw(size_t size) {
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size = (size + 7) & -8;
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auto buf_size = TD_OFFSETOF(BufferRaw, data_) + size;
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if (buf_size < sizeof(BufferRaw)) {
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buf_size = sizeof(BufferRaw);
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}
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buffer_mem += buf_size;
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auto *buffer_raw = reinterpret_cast<BufferRaw *>(new char[buf_size]);
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new (buffer_raw) BufferRaw();
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buffer_raw->data_size_ = size;
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buffer_raw->begin_ = 0;
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buffer_raw->end_ = 0;
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buffer_raw->ref_cnt_.store(1, std::memory_order_relaxed);
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buffer_raw->has_writer_.store(true, std::memory_order_relaxed);
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buffer_raw->was_reader_ = false;
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return buffer_raw;
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}
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} // namespace td
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