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coreaudio: fix undefined behavior when flushing

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Don't consume (calling TPCircularBufferClear()) from the producer thread
(ca_Flush()).
This commit is contained in:
Thomas Guillem 2017-09-06 11:23:47 +02:00
parent e21706e9e3
commit 9ad50ca913
2 changed files with 18 additions and 2 deletions
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17
modules/audio_output/coreaudio_common.c
View File

@ -48,6 +48,14 @@ ca_Render(audio_output_t *p_aout, uint8_t *p_output, size_t i_requested)
{
struct aout_sys_common *p_sys = (struct aout_sys_common *) p_aout->sys;
bool expected = true;
if (atomic_compare_exchange_weak(&p_sys->b_do_flush, &expected, false))
{
TPCircularBufferClear(&p_sys->circular_buffer);
/* Signal that the renderer is flushed */
vlc_sem_post(&p_sys->flush_sem);
}
if (atomic_load_explicit(&p_sys->b_paused, memory_order_relaxed))
{
memset(p_output, 0, i_requested);
@ -112,8 +120,10 @@ ca_Flush(audio_output_t *p_aout, bool wait)
}
else
{
/* flush circular buffer if data is left */
TPCircularBufferClear(&p_sys->circular_buffer);
/* Request the renderer to flush, and wait for an ACK */
assert(!atomic_load(&p_sys->b_do_flush));
atomic_store_explicit(&p_sys->b_do_flush, true, memory_order_release);
vlc_sem_wait(&p_sys->flush_sem);
}
}
@ -183,6 +193,8 @@ ca_Initialize(audio_output_t *p_aout, const audio_sample_format_t *fmt,
atomic_init(&p_sys->i_underrun_size, 0);
atomic_init(&p_sys->b_paused, false);
atomic_init(&p_sys->b_do_flush, false);
vlc_sem_init(&p_sys->flush_sem, 0);
p_sys->i_rate = fmt->i_rate;
p_sys->i_bytes_per_frame = fmt->i_bytes_per_frame;
@ -232,6 +244,7 @@ ca_Uninitialize(audio_output_t *p_aout)
/* clean-up circular buffer */
TPCircularBufferCleanup(&p_sys->circular_buffer);
vlc_sem_destroy(&p_sys->flush_sem);
}
AudioUnit

3
modules/audio_output/coreaudio_common.h
View File

@ -29,6 +29,7 @@
#import <vlc_common.h>
#import <vlc_atomic.h>
#import <vlc_aout.h>
#import <vlc_threads.h>
#import <AudioUnit/AudioUnit.h>
#import <AudioToolbox/AudioToolbox.h>
@ -53,6 +54,8 @@ struct aout_sys_common
TPCircularBuffer circular_buffer;
atomic_uint i_underrun_size;
atomic_bool b_paused;
atomic_bool b_do_flush;
vlc_sem_t flush_sem;
int i_rate;
unsigned int i_bytes_per_frame;
unsigned int i_frame_length;