snapcast/server/streamreader/asio_stream.hpp

/***
    This file is part of snapcast
    Copyright (C) 2014-2021  Johannes Pohl

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
***/

#ifndef ASIO_STREAM_HPP
#define ASIO_STREAM_HPP

#include "common/aixlog.hpp"
#include "common/str_compat.hpp"
#include "pcm_stream.hpp"
#include <atomic>
#include <boost/asio.hpp>

namespace streamreader
{

template <typename ReadStream>
class AsioStream : public PcmStream
{
public:
    /// ctor. Encoded PCM data is passed to the PipeListener
    AsioStream(PcmListener* pcmListener, boost::asio::io_context& ioc, const ServerSettings& server_settings, const StreamUri& uri);

    void start() override;
    void stop() override;

    virtual void connect();
    virtual void disconnect();

protected:
    virtual void do_connect() = 0;
    virtual void do_disconnect() = 0;
    virtual void on_connect();
    virtual void do_read();
    void check_state();

    template <typename Timer, typename Rep, typename Period>
    void wait(Timer& timer, const std::chrono::duration<Rep, Period>& duration, std::function<void()> handler);

    std::unique_ptr<msg::PcmChunk> chunk_;
    timeval tv_chunk_;
    bool first_;
    std::chrono::time_point<std::chrono::steady_clock> nextTick_;
    uint32_t buffer_ms_;
    boost::asio::steady_timer read_timer_;
    boost::asio::steady_timer state_timer_;
    std::unique_ptr<ReadStream> stream_;
    std::atomic<std::uint64_t> bytes_read_;
};


template <typename ReadStream>
template <typename Timer, typename Rep, typename Period>
void AsioStream<ReadStream>::wait(Timer& timer, const std::chrono::duration<Rep, Period>& duration, std::function<void()> handler)
{
    timer.expires_after(duration);
    timer.async_wait([handler = std::move(handler)](const boost::system::error_code& ec) {
        if (ec)
        {
            LOG(ERROR, "AsioStream") << "Error during async wait: " << ec.message() << "\n";
        }
        else
        {
            handler();
        }
    });
}


template <typename ReadStream>
AsioStream<ReadStream>::AsioStream(PcmListener* pcmListener, boost::asio::io_context& ioc, const ServerSettings& server_settings, const StreamUri& uri)
    : PcmStream(pcmListener, ioc, server_settings, uri), read_timer_(ioc), state_timer_(ioc)
{
    chunk_ = std::make_unique<msg::PcmChunk>(sampleFormat_, chunk_ms_);
    LOG(DEBUG, "AsioStream") << "Chunk duration: " << chunk_->durationMs() << " ms, frames: " << chunk_->getFrameCount() << ", size: " << chunk_->payloadSize
                             << "\n";

    bytes_read_ = 0;
    buffer_ms_ = 50;

    try
    {
        buffer_ms_ = cpt::stoi(uri_.getQuery("buffer_ms", cpt::to_string(buffer_ms_)));
    }
    catch (...)
    {
    }
}


template <typename ReadStream>
void AsioStream<ReadStream>::check_state()
{
    uint64_t last_read = bytes_read_;
    wait(state_timer_, std::chrono::milliseconds(500 + chunk_ms_), [this, last_read] {
        LOG(TRACE, "AsioStream") << "check state last: " << last_read << ", read: " << bytes_read_ << "\n";
        if (bytes_read_ != last_read)
            setState(ReaderState::kPlaying);
        else
            setState(ReaderState::kIdle);
        check_state();
    });
}


template <typename ReadStream>
void AsioStream<ReadStream>::start()
{
    PcmStream::start();
    check_state();
    connect();
}


template <typename ReadStream>
void AsioStream<ReadStream>::connect()
{
    do_connect();
}


template <typename ReadStream>
void AsioStream<ReadStream>::disconnect()
{
    do_disconnect();
}


template <typename ReadStream>
void AsioStream<ReadStream>::stop()
{
    active_ = false;
    read_timer_.cancel();
    state_timer_.cancel();
    disconnect();
}


template <typename ReadStream>
void AsioStream<ReadStream>::on_connect()
{
    first_ = true;
    tvEncodedChunk_ = std::chrono::steady_clock::now();
    do_read();
}


template <typename ReadStream>
void AsioStream<ReadStream>::do_read()
{
    // LOG(DEBUG, "AsioStream") << "do_read\n";
    boost::asio::async_read(*stream_, boost::asio::buffer(chunk_->payload, chunk_->payloadSize),
                            [this](boost::system::error_code ec, std::size_t length) mutable {
                                if (ec)
                                {
                                    LOG(ERROR, "AsioStream") << "Error reading message: " << ec.message() << ", length: " << length << "\n";
                                    connect();
                                    return;
                                }

                                bytes_read_ += length;
                                // LOG(DEBUG, "AsioStream") << "Read: " << length << " bytes\n";
                                // First read after connect. Set the initial read timestamp
                                // the timestamp will be incremented after encoding,
                                // since we do not know how much the encoder actually encoded

                                if (!first_)
                                {
                                    auto now = std::chrono::steady_clock::now();
                                    auto stream2systime_diff = now - tvEncodedChunk_;
                                    if (stream2systime_diff > chronos::sec(5) + chronos::msec(chunk_ms_))
                                    {
                                        LOG(WARNING, "AsioStream") << "Stream and system time out of sync: "
                                                                   << std::chrono::duration_cast<std::chrono::microseconds>(stream2systime_diff).count() / 1000.
                                                                   << " ms, resetting stream time.\n";
                                        first_ = true;
                                    }
                                }
                                if (first_)
                                {
                                    first_ = false;
                                    tvEncodedChunk_ = std::chrono::steady_clock::now() - chunk_->duration<std::chrono::nanoseconds>();
                                    nextTick_ = std::chrono::steady_clock::now();
                                }

                                chunkRead(*chunk_);
                                nextTick_ += chunk_->duration<std::chrono::nanoseconds>();
                                auto currentTick = std::chrono::steady_clock::now();

                                // Synchronize read to chunk_ms_
                                if (nextTick_ >= currentTick)
                                {
                                    read_timer_.expires_after(nextTick_ - currentTick);
                                    read_timer_.async_wait([this](const boost::system::error_code& ec) {
                                        if (ec)
                                        {
                                            LOG(ERROR, "AsioStream") << "Error during async wait: " << ec.message() << "\n";
                                        }
                                        else
                                        {
                                            do_read();
                                        }
                                    });
                                    return;
                                }
                                // Read took longer, wait for the buffer to fill up
                                else
                                {
                                    resync(std::chrono::duration_cast<std::chrono::nanoseconds>(currentTick - nextTick_));
                                    nextTick_ = currentTick + std::chrono::milliseconds(buffer_ms_);
                                    first_ = true;
                                    do_read();
                                }
                            });
}

} // namespace streamreader

#endif