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/*
* Copyright 2003-2021 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_MUSIC_BUFFER_HXX
#define MPD_MUSIC_BUFFER_HXX
#include "MusicChunkPtr.hxx"
#include "util/SliceBuffer.hxx"
#include "thread/Mutex.hxx"
/**
* An allocator for #MusicChunk objects.
*/
class MusicBuffer {
/** a mutex which protects #buffer */
mutable Mutex mutex;
SliceBuffer<MusicChunk> buffer;
public:
/**
* Creates a new #MusicBuffer object.
*
* @param num_chunks the number of #MusicChunk reserved in
* this buffer
*/
explicit MusicBuffer(unsigned num_chunks);
#ifndef NDEBUG
/**
* Check whether the buffer is empty. This call is not
* protected with the mutex, and may only be used while this
* object is inaccessible to other threads.
*/
bool IsEmptyUnsafe() const {
return buffer.empty();
}
#endif
bool IsFull() const noexcept {
const std::lock_guard<Mutex> protect(mutex);
return buffer.IsFull();
}
/**
* Returns the total number of reserved chunks in this buffer. This
* is the same value which was passed to the constructor
* music_buffer_new().
*/
gcc_pure
unsigned GetSize() const noexcept {
return buffer.GetCapacity();
}
/**
* Allocates a chunk from the buffer. When it is not used anymore,
* call Return().
*
* @return an empty chunk or nullptr if there are no chunks
* available
*/
MusicChunkPtr Allocate() noexcept;
/**
* Returns a chunk to the buffer. It can be reused by
* Allocate() then.
*/
void Return(MusicChunk *chunk) noexcept;
};
#endif
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