159 lines
3.9 KiB
C++
159 lines
3.9 KiB
C++
/*
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Copyright (c) 2019 yvt
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This file is part of OpenSpades.
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OpenSpades is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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OpenSpades is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with OpenSpades. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <algorithm>
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#include <condition_variable>
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#include <cstdint>
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#include <deque>
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#include <memory>
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#include <mutex>
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#include "PipeStream.h"
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namespace spades {
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namespace {
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struct State {
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/** Protects the state from simultaneous access. */
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std::mutex mutex;
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/** Used to notify changes in the state. */
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std::condition_variable condvar;
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/**
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* The ring buffer.
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*
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* Might not be the most efficient choice... But it has a good time complexity.
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*/
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std::deque<char> buffer;
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/** `true` if the writer has hanged up. */
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bool writerHangup = false;
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/** `true` if the reader has hanged up. */
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bool readerHangup = false;
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};
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struct PipeWriter : public IStream {
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std::shared_ptr<State> state;
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PipeWriter(std::shared_ptr<State> state) : state{std::move(state)} {}
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~PipeWriter() {
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{
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std::lock_guard<std::mutex> _lock{state->mutex};
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state->writerHangup = true;
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}
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// The reader must stop waiting
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state->condvar.notify_one();
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}
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void WriteByte(int byte) override {
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auto value = static_cast<std::uint8_t>(byte);
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Write(&value, 1);
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}
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void Write(const void *data, size_t numBytes) override {
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{
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std::lock_guard<std::mutex> _lock{state->mutex};
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auto inputBytes = reinterpret_cast<const char *>(data);
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if (state->readerHangup) {
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return;
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}
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// Allocate the space for incoming bytes
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size_t prevSize = state->buffer.size();
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state->buffer.resize(prevSize + numBytes);
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for (auto it = state->buffer.begin() + prevSize; it != state->buffer.end();
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++it) {
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*it = *(inputBytes++);
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}
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}
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// Wake up the reader
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state->condvar.notify_one();
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}
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};
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struct PipeReader : public IStream {
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std::shared_ptr<State> state;
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PipeReader(std::shared_ptr<State> state) : state{std::move(state)} {}
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~PipeReader() {
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std::lock_guard<std::mutex> _lock{state->mutex};
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state->readerHangup = true;
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// Deallocate the ring buffer
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std::deque<char> other;
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state->buffer.swap(other);
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}
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int ReadByte() override {
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std::uint8_t value;
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if (Read(&value, 1)) {
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return value;
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} else {
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return -1;
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}
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}
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size_t Read(void *data, size_t numBytes) override {
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auto outputBytes = reinterpret_cast<char *>(data);
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size_t numActualRead = 0;
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std::unique_lock<std::mutex> lock{state->mutex};
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while (numActualRead < numBytes) {
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state->condvar.wait(
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lock, [&] { return !state->buffer.empty() || state->writerHangup; });
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if (state->writerHangup && state->buffer.empty()) {
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break;
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}
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// Copy data from the ring buffer
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size_t numAdditionalBytes =
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std::min(state->buffer.size(), numBytes - numActualRead);
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auto it = state->buffer.begin();
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for (; numAdditionalBytes; --numAdditionalBytes, ++it) {
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*(outputBytes++) = *it;
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++numActualRead;
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}
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// Update the ring buffer
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state->buffer.erase(state->buffer.begin(), it);
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}
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return numActualRead;
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}
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};
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} // namespace
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std::tuple<IStream *, IStream *> CreatePipeStream() {
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auto state = std::make_shared<State>();
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return std::make_tuple(new PipeWriter(state), new PipeReader(state));
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}
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} // namespace spades
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