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Fix #8335: Race condition in music mixer (#9450)

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Charles Pigott 2021-07-21 10:32:33 +01:00 committed by GitHub
parent dd54e4c835
commit 6c33b4ed28
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1 changed files with 21 additions and 14 deletions
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35
src/mixer.cpp
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@ -9,12 +9,13 @@
#include "stdafx.h"
#include <math.h>
#include <mutex>
#include "core/math_func.hpp"
#include "framerate_type.h"
#include "settings_type.h"
#include "safeguards.h"
#include "mixer.h"
#include "mixer.h"
struct MixerChannel {
bool active;
@ -39,6 +40,7 @@ static MixerChannel _channels[8];
static uint32 _play_rate = 11025;
static uint32 _max_size = UINT_MAX;
static MxStreamCallback _music_stream = nullptr;
static std::mutex _music_stream_mutex;
/**
* The theoretical maximum volume for a single sound sample. Multiple sound
@ -152,8 +154,11 @@ void MxMixSamples(void *buffer, uint samples)
/* Clear the buffer */
memset(buffer, 0, sizeof(int16) * 2 * samples);
/* Fetch music if a sampled stream is available */
if (_music_stream) _music_stream((int16*)buffer, samples);
{
std::lock_guard<std::mutex> lock{ _music_stream_mutex };
/* Fetch music if a sampled stream is available */
if (_music_stream) _music_stream((int16*)buffer, samples);
}
/* Apply simple x^3 scaling to master effect volume. This increases the
* perceived difference in loudness to better match expectations. effect_vol
@ -227,22 +232,24 @@ void MxSetChannelVolume(MixerChannel *mc, uint volume, float pan)
void MxActivateChannel(MixerChannel *mc)
{
mc->active = true;
}
/**
* Set source of PCM music
* @param music_callback Function that will be called to fill sample buffers with music data.
* @return Sample rate of mixer, which the buffers supplied to the callback must be rendered at.
*/
uint32 MxSetMusicSource(MxStreamCallback music_callback)
{
_music_stream = music_callback;
return _play_rate;
}
/**
* Set source of PCM music
* @param music_callback Function that will be called to fill sample buffers with music data.
* @return Sample rate of mixer, which the buffers supplied to the callback must be rendered at.
*/
uint32 MxSetMusicSource(MxStreamCallback music_callback)
{
std::lock_guard<std::mutex> lock{ _music_stream_mutex };
_music_stream = music_callback;
return _play_rate;
}
bool MxInitialize(uint rate)
{
std::lock_guard<std::mutex> lock{ _music_stream_mutex };
_play_rate = rate;
_max_size = UINT_MAX / _play_rate;
_music_stream = nullptr; /* rate may have changed, any music source is now invalid */