mpd/src/MusicPipe.hxx
2023-03-06 14:59:48 +01:00

99 lines
1.9 KiB
C++

// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright The Music Player Daemon Project
#ifndef MPD_PIPE_H
#define MPD_PIPE_H
#include "MusicChunkPtr.hxx"
#include "thread/Mutex.hxx"
#ifndef NDEBUG
#include "pcm/AudioFormat.hxx"
#endif
/**
* A queue of #MusicChunk objects. One party appends chunks at the
* tail, and the other consumes them from the head.
*/
class MusicPipe {
/** the first chunk */
MusicChunkPtr head;
/** a pointer to the tail of the chunk */
MusicChunkPtr *tail_r = &head;
/** the current number of chunks */
unsigned size = 0;
/** a mutex which protects #head and #tail_r */
mutable Mutex mutex;
#ifndef NDEBUG
AudioFormat audio_format = AudioFormat::Undefined();
#endif
public:
~MusicPipe() noexcept {
Clear();
}
#ifndef NDEBUG
/**
* Checks if the audio format if the chunk is equal to the specified
* audio_format.
*/
[[gnu::pure]]
bool CheckFormat(AudioFormat other) const noexcept {
return !audio_format.IsDefined() ||
audio_format == other;
}
/**
* Checks if the specified chunk is enqueued in the music pipe.
*/
[[gnu::pure]]
bool Contains(const MusicChunk *chunk) const noexcept;
#endif
/**
* Returns the first #MusicChunk from the pipe. Returns
* nullptr if the pipe is empty.
*/
[[gnu::pure]]
const MusicChunk *Peek() const noexcept {
const std::scoped_lock<Mutex> protect(mutex);
return head.get();
}
/**
* Removes the first chunk from the head, and returns it.
*/
MusicChunkPtr Shift() noexcept;
/**
* Clears the whole pipe and returns the chunks to the buffer.
*/
void Clear() noexcept;
/**
* Pushes a chunk to the tail of the pipe.
*/
void Push(MusicChunkPtr chunk) noexcept;
/**
* Returns the number of chunks currently in this pipe.
*/
[[gnu::pure]]
unsigned GetSize() const noexcept {
const std::scoped_lock<Mutex> protect(mutex);
return size;
}
[[gnu::pure]]
bool IsEmpty() const noexcept {
return GetSize() == 0;
}
};
#endif