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Buffer and source objects' allocated field is no longer atomic.
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The mixer thread now only cares whether it is marked AL_PLAYING, and doesn't
touch this field, and since API calls don't race, there's no need for
atomicity here.
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@icculus
icculus committed Jun 29, 2019
1 parent a08be74 commit a8924e7
Showing 1 changed file with 17 additions and 17 deletions.
34 changes: 17 additions & 17 deletions mojoal.c
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Expand Up @@ -378,7 +378,7 @@ static void free_simd_aligned(void *ptr)

typedef struct ALbuffer
{
SDL_atomic_t allocated;
ALboolean allocated;
ALuint name;
ALint channels;
ALint bits; /* always float32 internally, but this is what alBufferData saw */
Expand Down Expand Up @@ -419,9 +419,9 @@ SIMDALIGNEDSTRUCT ALsource
ALfloat velocity[4];
ALfloat direction[4];
ALfloat panning[2]; /* we only do stereo for now */
SDL_atomic_t allocated;
SDL_atomic_t mixer_accessible;
SDL_atomic_t state; /* initial, playing, paused, stopped */
ALboolean allocated;
ALenum type; /* undetermined, static, streaming */
ALboolean recalc;
ALboolean source_relative;
Expand Down Expand Up @@ -1674,8 +1674,9 @@ static ALCboolean mix_source(ALCcontext *ctx, ALsource *src, float *stream, int
{
ALCboolean keep;

keep = ((SDL_AtomicGet(&src->allocated) == 1) && (SDL_AtomicGet(&src->state) == AL_PLAYING));
keep = (SDL_AtomicGet(&src->state) == AL_PLAYING);
if (keep) {
SDL_assert(src->allocated);
if (src->recalc || force_recalc) {
SDL_MemoryBarrierAcquire();
src->recalc = AL_FALSE;
Expand Down Expand Up @@ -1773,7 +1774,8 @@ static void mix_disconnected_context(ALCcontext *ctx)

/* remove from playlist; all playing things got stopped, paused/initial/stopped shouldn't be listed. */
SDL_AtomicSet(&i->mixer_accessible, 1);
if ((SDL_AtomicGet(&i->allocated) == 1) && (SDL_AtomicGet(&i->state) == AL_PLAYING)) {
if (SDL_AtomicGet(&i->state) == AL_PLAYING) {
SDL_assert(i->allocated);
SDL_AtomicSet(&i->state, AL_STOPPED);
source_mark_all_buffers_processed(i);
}
Expand Down Expand Up @@ -1991,7 +1993,7 @@ static void _alcDestroyContext(ALCcontext *ctx)
ALsizei i;
for (i = 0; i < SDL_arraysize(sb->sources); i++) {
ALsource *src = &sb->sources[i];
if (!SDL_AtomicGet(&src->allocated)) {
if (!src->allocated) {
continue;
}

Expand Down Expand Up @@ -2492,7 +2494,7 @@ static ALsource *get_source(ALCcontext *ctx, const ALuint name, SourceBlock **_b

block = ctx->source_blocks[blockidx];
source = &block->sources[block_offset];
if (SDL_AtomicGet(&source->allocated) == 1) {
if (source->allocated) {
if (_block) *_block = block;
return source;
}
Expand Down Expand Up @@ -2522,7 +2524,7 @@ static ALbuffer *get_buffer(ALCcontext *ctx, const ALuint name, BufferBlock **_b

block = ctx->device->playback.buffer_blocks[blockidx];
buffer = &block->buffers[block_offset];
if (SDL_AtomicGet(&buffer->allocated) == 1) {
if (buffer->allocated) {
if (_block) *_block = block;
return buffer;
}
Expand Down Expand Up @@ -3319,7 +3321,7 @@ static void _alGenSources(const ALsizei n, ALuint *names)
src->cone_inner_angle = 360.0f;
src->cone_outer_angle = 360.0f;
source_needs_recalc(src);
SDL_AtomicSet(&src->allocated, 1); /* we officially own it. */
src->allocated = AL_TRUE; /* we officially own it. */
}

if (objects != stackobjs) SDL_free(objects);
Expand Down Expand Up @@ -3359,8 +3361,9 @@ static void _alDeleteSources(const ALsizei n, const ALuint *names)
SDL_assert(source != NULL);

/* "A playing source can be deleted--the source will be stopped automatically and then deleted." */
SDL_AtomicSet(&source->allocated, 0); /* will make mixer reject it if currently playing. */
SDL_AtomicSet(&source->state, AL_STOPPED); /* will make mixer reject it if currently playing. */
wait_if_source_is_mixing(ctx, source);
source->allocated = AL_FALSE;
source_release_buffer_queue(ctx, source);
if (source->buffer) {
SDL_assert(source->type == AL_STATIC);
Expand Down Expand Up @@ -4220,7 +4223,7 @@ static void _alGenBuffers(const ALsizei n, ALuint *names)
buffer->name = names[i];
buffer->channels = 1;
buffer->bits = 16;
SDL_AtomicSet(&buffer->allocated, 1); /* we officially own it. */
buffer->allocated = AL_TRUE; /* we officially own it. */
}

if (objects != stackobjs) SDL_free(objects);
Expand Down Expand Up @@ -4262,12 +4265,9 @@ static void _alDeleteBuffers(const ALsizei n, const ALuint *names)
void *data;
SDL_assert(buffer != NULL);
data = (void *) buffer->data;
if (!SDL_AtomicCAS(&buffer->allocated, 1, 0)) {
/* uh-oh!! */
} else {
buffer->data = NULL;
free_simd_aligned(data);
}
buffer->allocated = AL_FALSE;
buffer->data = NULL;
free_simd_aligned(data);
block->used--;
}
}
Expand Down Expand Up @@ -4310,7 +4310,7 @@ static void _alBufferData(const ALuint name, const ALenum alfmt, const ALvoid *d
}

/* This check was from the wild west of lock-free programming, now we shouldn't pass get_buffer() if not allocated. */
SDL_assert(SDL_AtomicGet(&buffer->allocated) == 1);
SDL_assert(buffer->allocated);

/* right now we take a moment to convert the data to float32, since that's
the format we want to work in, but we don't resample or change the channels */
Expand Down

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