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/*
* Copyright 2003-2017 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.
*/
#ifndef MPD_PIPE_H
#define MPD_PIPE_H
#include "thread/Mutex.hxx"
#include "Compiler.h"
#ifndef NDEBUG
#include "AudioFormat.hxx"
#endif
#include <assert.h>
struct MusicChunk;
class MusicBuffer;
/**
* 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 */
MusicChunk *head = nullptr;
/** a pointer to the tail of the chunk */
MusicChunk **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:
/**
* Creates a new #MusicPipe object. It is empty.
*/
MusicPipe() = default;
MusicPipe(const MusicPipe &) = delete;
/**
* Frees the object. It must be empty now.
*/
~MusicPipe() {
assert(head == nullptr);
assert(tail_r == &head);
}
MusicPipe &operator=(const MusicPipe &) = delete;
#ifndef NDEBUG
/**
* Checks if the audio format if the chunk is equal to the specified
* audio_format.
*/
gcc_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.
*/
gcc_pure
bool Contains(const MusicChunk *chunk) const noexcept;
#endif
/**
* Returns the first #MusicChunk from the pipe. Returns
* nullptr if the pipe is empty.
*/
gcc_pure
const MusicChunk *Peek() const noexcept {
return head;
}
/**
* Removes the first chunk from the head, and returns it.
*/
MusicChunk *Shift() noexcept;
/**
* Clears the whole pipe and returns the chunks to the buffer.
*
* @param buffer the buffer object to return the chunks to
*/
void Clear(MusicBuffer &buffer) noexcept;
/**
* Pushes a chunk to the tail of the pipe.
*/
void Push(MusicChunk *chunk) noexcept;
/**
* Returns the number of chunks currently in this pipe.
*/
gcc_pure
unsigned GetSize() const noexcept {
return size;
}
gcc_pure
bool IsEmpty() const noexcept {
return GetSize() == 0;
}
};
#endif
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