Thread safety stuff

git-svn-id: svn://cook.msm.cam.ac.uk:745/thrust3d/thrust3d@126 84d2e878-0bd5-11dd-ad15-13eda11d74c5

1 files changed, 124 insertions, 18 deletions

diff --git a/src/audio.c b/src/audio.c
index bf8343b..d252086 100644
--- a/src/audio.c
+++ b/src/audio.c
@@ -95,7 +95,11 @@ static void audio_mix(void *data, Uint8 *stream8, int len) {
 	
 }
 
-static void audio_play_wav(AudioContext *a, char *filename, float volume, int repeat) {
+static void *audio_play_wav(void *add_void) {
+
+	AudioDispatchData *add = add_void;
+	AudioContext *a = add->audiocontext;
+	char *filename = add->filename;
 
 	int idx;
 	SDL_AudioSpec wave;
@@ -104,37 +108,47 @@ static void audio_play_wav(AudioContext *a, char *filename, float volume, int re
 	SDL_AudioCVT cvt;
 	
 	/* Look for an empty sound slot */
+	pthread_mutex_lock(&a->sounds_mutex);
 	for ( idx=0; idx<AUDIO_MAX_SOUNDS; idx++ ) {
 		if ( !a->sounds[idx].inuse ) break;
 	}
 	if ( idx == AUDIO_MAX_SOUNDS ) {
 		fprintf(stderr, "Not enough audio channels to play '%s'\n", filename);
-		return;
+		return NULL;
 	}
 	a->sounds[idx].inuse = 1;
+	pthread_mutex_unlock(&a->sounds_mutex);
 	if ( a->debug ) printf("AU: Channel %i: Selected this channel for sound '%s'\n", idx, filename);
 	
 	/* Load the sound file and convert it to 16-bit stereo at 44.1 kHz */
 	if ( SDL_LoadWAV(filename, &wave, &data, &dlen) == NULL ) {
 		fprintf(stderr, "Couldn't load %s: (channel %i) %s\n", filename, idx, SDL_GetError());
-		return;
+		return NULL;
 	}
 	SDL_BuildAudioCVT(&cvt, wave.format, wave.channels, wave.freq, AUDIO_S16, 2, 44100);
 	cvt.buf = malloc(dlen*cvt.len_mult);
+	if ( cvt.buf == NULL ) {
+		fprintf(stderr, "Not enough memory to convert audio (channel %i)\n", idx);
+	}
 	memcpy(cvt.buf, data, dlen);
 	cvt.len = dlen;
 	SDL_ConvertAudio(&cvt);
 	SDL_FreeWAV(data);
 	
 	/* Put the sound data in the slot */
-	SDL_LockAudio();
 	a->sounds[idx].data = (Sint16 *)cvt.buf;
 	a->sounds[idx].dlen = cvt.len_cvt / 2;
 	a->sounds[idx].dpos = 0;
-	a->sounds[idx].playing = 1;
-	a->sounds[idx].repeat = repeat;
-	a->sounds[idx].volume = volume;
-	SDL_UnlockAudio();
+	a->sounds[idx].repeat = add->repeat;
+	a->sounds[idx].volume = add->volume;
+	a->sounds[idx].playing = 1;	/* Must be done last - tell the mixer thread it can use this */
+	
+	free(add->filename);
+	if ( a->debug ) printf("AU: Channel %i: WAV dispatch thread completed.\n", idx);
+	a->dispatch_threads_inuse[add->idx] = 0;
+	free(add);
+	
+	return NULL;
 	
 }
 
@@ -154,6 +168,7 @@ static void *audio_play_vorbis(void *add_void) {
 	SDL_AudioCVT cvt;
 	
 	/* Look for an empty sound slot */
+	pthread_mutex_lock(&a->sounds_mutex);
 	for ( idx=0; idx<AUDIO_MAX_SOUNDS; idx++ ) {
 		if ( !a->sounds[idx].inuse ) break;
 	}
@@ -162,6 +177,7 @@ static void *audio_play_vorbis(void *add_void) {
 		return NULL;
 	}
 	a->sounds[idx].inuse = 1;
+	pthread_mutex_unlock(&a->sounds_mutex);
 	if ( a->debug ) printf("AU: Channel %i: Selected this channel for sound '%s'\n", idx, filename);
 	
 	err = ov_fopen(filename, &vf);
@@ -175,6 +191,9 @@ static void *audio_play_vorbis(void *add_void) {
 	vi = ov_info(&vf,-1);
 	if ( a->debug ) printf("AU: Channel %i: %i channels, %li Hz\n", idx, vi->channels, vi->rate);
 	data = malloc(vi->channels*2*len);	/* Two bytes per sample per channel */
+	if ( data == NULL ) {
+		fprintf(stderr, "Not enough memory to decode Vorbis stream (channel %i)\n", idx);
+	}
 	
 	offs = 0;
 	finished = 0;
@@ -194,25 +213,29 @@ static void *audio_play_vorbis(void *add_void) {
 	/* Convert to 44.1 kHz */
 	SDL_BuildAudioCVT(&cvt, AUDIO_S16, vi->channels, vi->rate, AUDIO_S16, 2, 44100);
 	cvt.buf = malloc(vi->channels*2*len*cvt.len_mult);
+	if ( cvt.buf == NULL ) {
+		fprintf(stderr, "Not enough memory to convert audio (channel %i)\n", idx);
+	}
 	memcpy(cvt.buf, data, vi->channels*2*len);
 	cvt.len = vi->channels*2*len;
 	SDL_ConvertAudio(&cvt);
+	free(data);
 	
 	ov_clear(&vf);
 	
 	/* Put the sound data in the slot */
-	SDL_LockAudio();
 	a->sounds[idx].data = (Sint16 *)cvt.buf;
 	a->sounds[idx].dlen = cvt.len_cvt / 2;
 	a->sounds[idx].dpos = 0;
-	a->sounds[idx].playing = 1;
 	a->sounds[idx].repeat = add->repeat;
 	a->sounds[idx].volume = add->volume;
-	SDL_UnlockAudio();
+	a->sounds[idx].playing = 1;	/* Must be done last - tell the mixer thread it can use this */
 	
 	free(add->filename);
+	if ( a->debug ) printf("AU: Channel %i: Vorbis dispatch thread completed.\n", idx);
+	a->dispatch_threads_inuse[add->idx] = 0;
 	free(add);
-	if ( a->debug ) printf("AU: Channel %i: audio_play_vorbis dispatch thread completed.\n", idx);
+	
 	return NULL;
 	
 }
@@ -226,18 +249,40 @@ void audio_play(AudioContext *a, char *name, float volume, int repeat) {
 	snprintf(filename, 127, "%s%s.ogg", DATADIR"/sound/", name);
 	if ( stat(filename, &statbuf) == 0 ) {
 		
-		int rval;
+		int rval, idx;
 		AudioDispatchData *add;
-		pthread_t thread;
+		pthread_attr_t attr;
 		
 		add = malloc(sizeof(AudioDispatchData));
 		add->audiocontext = a;
 		add->filename = strdup(filename);
 		add->volume = volume;
 		add->repeat = repeat;
-		rval = pthread_create(&thread, NULL, audio_play_vorbis, add);
+		
+		/* Claim a dispatch thread slot */
+		for ( idx=0; idx<AUDIO_MAX_SOUNDS; idx++ ) {
+			if ( !a->dispatch_threads_inuse[idx] ) break;
+		}
+		if ( idx == AUDIO_MAX_SOUNDS ) {
+			fprintf(stderr, "Not enough dispatch thread space to play '%s'\n", filename);
+			free(add->filename);
+			free(add);
+			return;
+		}
+		a->dispatch_threads_inuse[idx] = 1;
+		add->idx = idx;
+		
+		/* Start the dispatch thread */
+		pthread_attr_init(&attr);
+		pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+		rval = pthread_create(&a->dispatch_threads[idx], &attr, audio_play_vorbis, add);
+		pthread_attr_destroy(&attr);
 		if ( rval != 0 ) {
 			fprintf(stderr, "Couldn't create audio dispatch thread (%i)\n", rval);
+			free(add->filename);
+			free(add);
+			a->dispatch_threads_inuse[idx] = 0;
+			return;
 		}
 		
 		goto done;
@@ -247,8 +292,45 @@ void audio_play(AudioContext *a, char *name, float volume, int repeat) {
 	/* Try to find a WAV file */
 	snprintf(filename, 127, "%s%s.wav", DATADIR"/sound/", name);
 	if ( stat(filename, &statbuf) == 0 ) {
-		audio_play_wav(a, filename, volume, repeat);
+		
+		int rval, idx;
+		AudioDispatchData *add;
+		pthread_attr_t attr;
+		
+		add = malloc(sizeof(AudioDispatchData));
+		add->audiocontext = a;
+		add->filename = strdup(filename);
+		add->volume = volume;
+		add->repeat = repeat;
+		
+		/* Claim a dispatch thread slot */
+		for ( idx=0; idx<AUDIO_MAX_SOUNDS; idx++ ) {
+			if ( !a->dispatch_threads_inuse[idx] ) break;
+		}
+		if ( idx == AUDIO_MAX_SOUNDS ) {
+			fprintf(stderr, "Not enough dispatch thread space to play '%s'\n", filename);
+			free(add->filename);
+			free(add);
+			return;
+		}
+		a->dispatch_threads_inuse[idx] = 1;
+		add->idx = idx;
+		
+		/* Start the dispatch thread */
+		pthread_attr_init(&attr);
+		pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+		rval = pthread_create(&a->dispatch_threads[idx], &attr, audio_play_wav, add);
+		pthread_attr_destroy(&attr);
+		if ( rval != 0 ) {
+			fprintf(stderr, "Couldn't create audio dispatch thread (%i)\n", rval);
+			free(add->filename);
+			free(add);
+			a->dispatch_threads_inuse[idx] = 0;
+			return;
+		}
+		
 		goto done;
+		
 	}
 	
 	/* Still not found */
@@ -280,9 +362,11 @@ AudioContext *audio_setup(int debug) {
 	a->startup = 1;
 	a->startup_volume = 0.0;
 	a->paused = 1;
+	pthread_mutex_init(&a->sounds_mutex, NULL);
 	for ( i=0; i<AUDIO_MAX_SOUNDS; i++ ) {
 		a->sounds[i].inuse = 0;
 		a->sounds[i].playing = 0;
+		a->dispatch_threads[i] = 0;
 	}
 	
 	/* 16-bit stereo audio at 44.1 kHz */
@@ -307,8 +391,30 @@ AudioContext *audio_setup(int debug) {
 	
 }
 
-void audio_shutdown(AudioContext *ctx) {
+void audio_shutdown(AudioContext *a) {
+
+	int i;
+	
 	SDL_CloseAudio();
-	free(ctx);
+	
+	/* Wait for dispatch threads */
+	for ( i=0; i<AUDIO_MAX_SOUNDS; i++ ) {
+		if ( a->dispatch_threads_inuse[i] ) {
+			pthread_join(a->dispatch_threads[i], NULL);
+		}
+	}
+	
+	/* Now that all the dispatch threads are done, and the mixer callback
+	   is no longer getting called, the sound system is in a consistent
+	   state. i.e. 'inuse' means memory is allocated and can be freed */
+	for ( i=0; i<AUDIO_MAX_SOUNDS; i++ ) {
+		if ( a->sounds[i].inuse ) {
+			free(a->sounds[i].data);
+		}
+	}
+	
+	/* Now this can be freed */
+	free(a);
+	
 }