4e0e4c00bf
SonarLint reports the latter to be better:
std::scoped_lock basically provides the same feature as std::lock_guard,
but is more generic: It can lock several mutexes at the same time, with a
deadlock prevention mechanism (see {rule:cpp:S5524}). The equivalent code
to perform simultaneous locking with std::lock_guard is significantly more
complex. Therefore, it is simpler to use std::scoped_lock all the time,
even when locking only one mutex (there will be no performance impact).
Signed-off-by: Rosen Penev <rosenp@gmail.com>
115 lines
2.6 KiB
C++
115 lines
2.6 KiB
C++
/*
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* Copyright 2003-2021 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_PIPE_H
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#define MPD_PIPE_H
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#include "MusicChunkPtr.hxx"
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#include "thread/Mutex.hxx"
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#ifndef NDEBUG
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#include "pcm/AudioFormat.hxx"
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#endif
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/**
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* A queue of #MusicChunk objects. One party appends chunks at the
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* tail, and the other consumes them from the head.
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*/
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class MusicPipe {
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/** the first chunk */
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MusicChunkPtr head;
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/** a pointer to the tail of the chunk */
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MusicChunkPtr *tail_r = &head;
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/** the current number of chunks */
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unsigned size = 0;
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/** a mutex which protects #head and #tail_r */
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mutable Mutex mutex;
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#ifndef NDEBUG
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AudioFormat audio_format = AudioFormat::Undefined();
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#endif
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public:
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~MusicPipe() noexcept {
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Clear();
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}
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#ifndef NDEBUG
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/**
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* Checks if the audio format if the chunk is equal to the specified
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* audio_format.
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*/
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[[gnu::pure]]
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bool CheckFormat(AudioFormat other) const noexcept {
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return !audio_format.IsDefined() ||
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audio_format == other;
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}
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/**
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* Checks if the specified chunk is enqueued in the music pipe.
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*/
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[[gnu::pure]]
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bool Contains(const MusicChunk *chunk) const noexcept;
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#endif
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/**
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* Returns the first #MusicChunk from the pipe. Returns
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* nullptr if the pipe is empty.
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*/
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[[gnu::pure]]
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const MusicChunk *Peek() const noexcept {
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const std::scoped_lock<Mutex> protect(mutex);
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return head.get();
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}
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/**
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* Removes the first chunk from the head, and returns it.
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*/
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MusicChunkPtr Shift() noexcept;
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/**
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* Clears the whole pipe and returns the chunks to the buffer.
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*/
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void Clear() noexcept;
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/**
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* Pushes a chunk to the tail of the pipe.
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*/
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void Push(MusicChunkPtr chunk) noexcept;
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/**
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* Returns the number of chunks currently in this pipe.
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*/
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[[gnu::pure]]
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unsigned GetSize() const noexcept {
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const std::scoped_lock<Mutex> protect(mutex);
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return size;
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}
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[[gnu::pure]]
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bool IsEmpty() const noexcept {
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return GetSize() == 0;
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}
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};
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#endif
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