mpd/src/output/Control.hxx

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/*
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* Copyright 2003-2018 The Music Player Daemon Project
* http://www.musicpd.org
*
* 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 2 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
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#ifndef MPD_OUTPUT_CONTROL_HXX
#define MPD_OUTPUT_CONTROL_HXX
#include "Source.hxx"
#include "AudioFormat.hxx"
#include "thread/Thread.hxx"
#include "thread/Mutex.hxx"
#include "thread/Cond.hxx"
#include "system/PeriodClock.hxx"
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#include "util/Compiler.h"
#include <utility>
#include <exception>
#include <memory>
#include <string>
#include <map>
#ifndef NDEBUG
#include <assert.h>
#endif
#include <stdint.h>
enum class ReplayGainMode : uint8_t;
struct FilteredAudioOutput;
struct MusicChunk;
struct ConfigBlock;
class MusicPipe;
class Mixer;
class AudioOutputClient;
/**
* Controller for an #AudioOutput and its output thread.
*/
class AudioOutputControl {
std::unique_ptr<FilteredAudioOutput> output;
/**
* The PlayerControl object which "owns" this output. This
* object is needed to signal command completion.
*/
AudioOutputClient &client;
/**
* Source of audio data.
*/
AudioOutputSource source;
/**
* The error that occurred in the output thread. It is
* cleared whenever the output is opened successfully.
*
* Protected by #mutex.
*/
std::exception_ptr last_error;
/**
* If not nullptr, the device has failed, and this timer is used
* to estimate how long it should stay disabled (unless
* explicitly reopened with "play").
*/
PeriodClock fail_timer;
/**
* The thread handle, or nullptr if the output thread isn't
* running.
*/
Thread thread;
/**
* This condition object wakes up the output thread after
* #command has been set.
*/
Cond wake_cond;
/**
* This condition object signals #command completion to the
* client.
*/
Cond client_cond;
/**
* Additional data for #command. Protected by #mutex.
*/
struct Request {
/**
* The #AudioFormat requested by #Command::OPEN.
*/
AudioFormat audio_format;
/**
* The #MusicPipe passed to #Command::OPEN.
*/
const MusicPipe *pipe;
} request;
/**
* The next command to be performed by the output thread.
*/
enum class Command {
NONE,
ENABLE,
DISABLE,
/**
* Open the output, or reopen it if it is already
* open, adjusting for input #AudioFormat changes.
*/
OPEN,
CLOSE,
PAUSE,
/**
* Close or pause the device, depending on the
* #always_on setting.
*/
RELEASE,
/**
* Drains the internal (hardware) buffers of the device. This
* operation may take a while to complete.
*/
DRAIN,
CANCEL,
KILL
} command = Command::NONE;
/**
* Will this output receive tags from the decoder? The
* default is true, but it may be configured to false to
* suppress sending tags to the output.
*/
bool tags;
/**
* Shall this output always play something (i.e. silence),
* even when playback is stopped?
*/
bool always_on;
/**
* Has the user enabled this device?
*/
bool enabled = true;
/**
* Is this device actually enabled, i.e. the "enable" method
* has succeeded?
*/
bool really_enabled = false;
/**
* Is the device (already) open and functional?
*
* This attribute may only be modified by the output thread.
* It is protected with #mutex: write accesses inside the
* output thread and read accesses outside of it may only be
* performed while the lock is held.
*/
bool open = false;
/**
* Is the device paused? i.e. the output thread is in the
* ao_pause() loop.
*/
bool pause = false;
/**
* When this flag is set, the output thread will not do any
* playback. It will wait until the flag is cleared.
*
* This is used to synchronize the "clear" operation on the
* shared music pipe during the CANCEL command.
*/
bool allow_play = true;
/**
* True while the OutputThread is inside ao_play(). This
* means the PlayerThread does not need to wake up the
* OutputThread when new chunks are added to the MusicPipe,
* because the OutputThread is already watching that.
*/
bool in_playback_loop = false;
/**
* Has the OutputThread been woken up to play more chunks?
* This is set by audio_output_play() and reset by ao_play()
* to reduce the number of duplicate wakeups.
*/
bool woken_for_play = false;
/**
* If this flag is set, then the next WaitForDelay() call is
* skipped. This is used to avoid delays after resuming
* playback.
*/
bool skip_delay;
public:
/**
* This mutex protects #open, #fail_timer, #pipe.
*/
mutable Mutex mutex;
AudioOutputControl(std::unique_ptr<FilteredAudioOutput> _output,
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AudioOutputClient &_client) noexcept;
~AudioOutputControl() noexcept;
AudioOutputControl(const AudioOutputControl &) = delete;
AudioOutputControl &operator=(const AudioOutputControl &) = delete;
/**
* Throws #std::runtime_error on error.
*/
void Configure(const ConfigBlock &block);
gcc_pure
const char *GetName() const noexcept;
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gcc_pure
const char *GetPluginName() const noexcept;
gcc_pure
const char *GetLogName() const noexcept;
AudioOutputClient &GetClient() noexcept {
return client;
}
gcc_pure
Mixer *GetMixer() const noexcept;
/**
* Caller must lock the mutex.
*/
bool IsEnabled() const noexcept {
return enabled;
}
/**
* @return true if the value has been modified
*/
bool LockSetEnabled(bool new_value) noexcept;
/**
* @return the new "enabled" value
*/
bool LockToggleEnabled() noexcept;
/**
* Caller must lock the mutex.
*/
bool IsOpen() const noexcept {
return open;
}
/**
* Caller must lock the mutex.
*/
bool IsBusy() const noexcept {
return IsOpen() && !IsCommandFinished();
}
/**
* Caller must lock the mutex.
*/
const std::exception_ptr &GetLastError() const noexcept {
return last_error;
}
void StartThread();
/**
* Caller must lock the mutex.
*/
bool IsCommandFinished() const noexcept {
return command == Command::NONE;
}
void CommandFinished() noexcept;
/**
* Waits for command completion.
*
* Caller must lock the mutex.
*/
void WaitForCommand(std::unique_lock<Mutex> &lock) noexcept;
void LockWaitForCommand() noexcept {
std::unique_lock<Mutex> lock(mutex);
WaitForCommand(lock);
}
/**
* Sends a command, but does not wait for completion.
*
* Caller must lock the mutex.
*/
void CommandAsync(Command cmd) noexcept;
/**
* Sends a command to the object and waits for completion.
*
* Caller must lock the mutex.
*/
void CommandWait(std::unique_lock<Mutex> &lock, Command cmd) noexcept;
/**
* Lock the object and execute the command synchronously.
*/
void LockCommandWait(Command cmd) noexcept;
void BeginDestroy() noexcept;
const std::map<std::string, std::string> GetAttributes() const noexcept;
void SetAttribute(std::string &&name, std::string &&value);
/**
* Enables the device, but don't wait for completion.
*
* Caller must lock the mutex.
*/
void EnableAsync();
/**
* Disables the device, but don't wait for completion.
*
* Caller must lock the mutex.
*/
void DisableAsync() noexcept;
/**
* Attempt to enable or disable the device as specified by the
* #enabled attribute; attempt to sync it with #really_enabled
* (wrapper for EnableAsync() or DisableAsync()).
*
* Caller must lock the mutex.
*/
void EnableDisableAsync();
void LockEnableDisableAsync() {
const std::lock_guard<Mutex> protect(mutex);
EnableDisableAsync();
}
void LockPauseAsync() noexcept;
void CloseWait(std::unique_lock<Mutex> &lock) noexcept;
void LockCloseWait() noexcept;
/**
* Closes the audio output, but if the "always_on" flag is set, put it
* into pause mode instead.
*/
void LockRelease() noexcept;
void SetReplayGainMode(ReplayGainMode _mode) noexcept {
source.SetReplayGainMode(_mode);
}
/**
* Caller must lock the mutex.
*
* Throws #std::runtime_error on error.
*/
void InternalOpen2(AudioFormat in_audio_format);
/**
* Caller must lock the mutex.
*/
bool Open(std::unique_lock<Mutex> &lock,
AudioFormat audio_format, const MusicPipe &mp) noexcept;
/**
* Opens or closes the device, depending on the "enabled"
* flag.
*
* @param force true to ignore the #fail_timer
* @return true if the device is open
*/
bool LockUpdate(const AudioFormat audio_format,
const MusicPipe &mp,
bool force) noexcept;
/**
* Did we already consumed this chunk?
*
* Caller must lock the mutex.
*/
gcc_pure
bool IsChunkConsumed(const MusicChunk &chunk) const noexcept;
gcc_pure
bool LockIsChunkConsumed(const MusicChunk &chunk) const noexcept;
/**
* There's only one chunk left in the pipe (#pipe), and all
* audio outputs have consumed it already. Clear the
* reference.
*
* This stalls playback to give the caller a chance to shift
* the #MusicPipe without getting disturbed; after this,
* LockAllowPlay() must be called to resume playback.
*/
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void ClearTailChunk(const MusicChunk &chunk) noexcept {
if (!IsOpen())
return;
source.ClearTailChunk(chunk);
allow_play = false;
}
/**
* Locking wrapper for ClearTailChunk().
*/
void LockClearTailChunk(const MusicChunk &chunk) noexcept {
const std::lock_guard<Mutex> lock(mutex);
ClearTailChunk(chunk);
}
void LockPlay() noexcept;
void LockDrainAsync() noexcept;
/**
* Clear the "allow_play" flag and send the "CANCEL" command
* asynchronously. To finish the operation, the caller has to
* call LockAllowPlay().
*/
void LockCancelAsync() noexcept;
/**
* Set the "allow_play" and signal the thread.
*/
void LockAllowPlay() noexcept;
private:
/**
* An error has occurred and this output is defunct.
*/
void Failure(std::exception_ptr e) noexcept {
last_error = e;
/* don't automatically reopen this device for 10
seconds */
fail_timer.Update();
}
/**
* Runs inside the OutputThread.
* Caller must lock the mutex.
* Handles exceptions.
*
* @return true on success
*/
bool InternalEnable() noexcept;
/**
* Runs inside the OutputThread.
* Caller must lock the mutex.
*/
void InternalDisable() noexcept;
/**
* Runs inside the OutputThread.
* Caller must lock the mutex.
* Handles exceptions.
*/
void InternalOpen(AudioFormat audio_format,
const MusicPipe &pipe) noexcept;
/**
* Runs inside the OutputThread.
* Caller must lock the mutex.
*/
void InternalCloseOutput(bool drain) noexcept;
/**
* Runs inside the OutputThread.
* Caller must lock the mutex.
*/
void InternalClose(bool drain) noexcept;
/**
* An error has occurred, and this output must be closed.
*/
void InternalCloseError(std::exception_ptr e) noexcept {
Failure(e);
InternalClose(false);
}
/**
* Runs inside the OutputThread.
* Caller must lock the mutex.
*/
void InternalCheckClose(bool drain) noexcept;
/**
* Wait until the output's delay reaches zero.
*
* @return true if playback should be continued, false if a
* command was issued
*/
bool WaitForDelay(std::unique_lock<Mutex> &lock) noexcept;
/**
* Caller must lock the mutex.
*/
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bool FillSourceOrClose() noexcept;
/**
* Caller must lock the mutex.
*/
bool PlayChunk(std::unique_lock<Mutex> &lock) noexcept;
/**
* Plays all remaining chunks, until the tail of the pipe has
* been reached (and no more chunks are queued), or until a
* command is received.
*
* Runs inside the OutputThread.
* Caller must lock the mutex.
* Handles exceptions.
*
* @return true if at least one chunk has been available,
* false if the tail of the pipe was already reached
*/
bool InternalPlay(std::unique_lock<Mutex> &lock) noexcept;
/**
* Runs inside the OutputThread.
* Caller must lock the mutex.
* Handles exceptions.
*/
void InternalPause(std::unique_lock<Mutex> &lock) noexcept;
/**
* Runs inside the OutputThread.
* Caller must lock the mutex.
* Handles exceptions.
*/
void InternalDrain() noexcept;
/**
* The OutputThread.
*/
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void Task() noexcept;
};
#endif