d0f6131ba4
Coverity discovered that the Pulse plugin could throw exceptions from Pause(), but that method was marked "noexcept" because its caller was not designed to catch exceptions. So instead of avoiding exceptions (by catching and logging them in each and every implementation), let's allow them, and do the catch/log game in the MPD core.
154 lines
4.0 KiB
C++
154 lines
4.0 KiB
C++
/*
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* Copyright 2003-2017 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program 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 2 of the License, or
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* (at your option) any later version.
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*
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* This program 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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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef MPD_AUDIO_OUTPUT_INTERFACE_HXX
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#define MPD_AUDIO_OUTPUT_INTERFACE_HXX
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#include <chrono>
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struct AudioFormat;
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struct Tag;
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class AudioOutput {
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const unsigned flags;
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bool need_fully_defined_audio_format = false;
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protected:
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static constexpr unsigned FLAG_ENABLE_DISABLE = 0x1;
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static constexpr unsigned FLAG_PAUSE = 0x2;
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public:
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explicit AudioOutput(unsigned _flags):flags(_flags) {}
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virtual ~AudioOutput() = default;
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AudioOutput(const AudioOutput &) = delete;
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AudioOutput &operator=(const AudioOutput &) = delete;
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bool SupportsEnableDisable() const {
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return flags & FLAG_ENABLE_DISABLE;
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}
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bool SupportsPause() const {
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return flags & FLAG_PAUSE;
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}
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bool GetNeedFullyDefinedAudioFormat() const {
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return need_fully_defined_audio_format;
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}
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/**
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* Plugins shall call this method if they require an
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* "audio_format" setting which evaluates
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* AudioFormat::IsFullyDefined().
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*/
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void NeedFullyDefinedAudioFormat() {
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need_fully_defined_audio_format = true;
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}
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/**
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* Enable the device. This may allocate resources, preparing
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* for the device to be opened.
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*
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* Throws #std::runtime_error on error.
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*/
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virtual void Enable() {}
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/**
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* Disables the device. It is closed before this method is
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* called.
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*/
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virtual void Disable() noexcept {}
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/**
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* Really open the device.
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*
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* Throws #std::runtime_error on error.
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*
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* @param audio_format the audio format in which data is going
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* to be delivered; may be modified by the plugin
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*/
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virtual void Open(AudioFormat &audio_format) = 0;
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/**
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* Close the device.
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*/
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virtual void Close() noexcept = 0;
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/**
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* Returns a positive number if the output thread shall further
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* delay the next call to Play() or Pause(), which will happen
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* until this function returns 0. This should be implemented
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* instead of doing a sleep inside the plugin, because this
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* allows MPD to listen to commands meanwhile.
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*
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* @return the duration to wait
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*/
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virtual std::chrono::steady_clock::duration Delay() const noexcept {
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return std::chrono::steady_clock::duration::zero();
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}
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/**
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* Display metadata for the next chunk. Optional method,
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* because not all devices can display metadata.
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*/
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virtual void SendTag(const Tag &) {}
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/**
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* Play a chunk of audio data.
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*
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* Throws #std::runtime_error on error.
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*
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* @return the number of bytes played
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*/
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virtual size_t Play(const void *chunk, size_t size) = 0;
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/**
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* Wait until the device has finished playing.
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*/
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virtual void Drain() {}
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/**
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* Try to cancel data which may still be in the device's
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* buffers.
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*/
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virtual void Cancel() noexcept {}
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/**
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* Pause the device. If supported, it may perform a special
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* action, which keeps the device open, but does not play
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* anything. Output plugins like "shout" might want to play
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* silence during pause, so their clients won't be
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* disconnected. Plugins which do not support pausing will
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* simply be closed, and have to be reopened when unpaused.
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*
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* @return false on error (output will be closed by caller),
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* true for continue to pause
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*
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* Instead of returning false, the method may throw an
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* exception, which will be logged.
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*/
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virtual bool Pause() {
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/* fail because this method is not implemented */
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return false;
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}
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};
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#endif
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