Mercurial > almixer_isolated

changeset 29:1c23805d5ce9

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Optimization to destroy bookkeeping thread on BeginInterruption() and recreate it on EndInterruption(). I'm concerned that Android may be running this thread and eating up unnecessary sleep cycles, particularly on certain devices that may have pathological sleep disorders. (There is a report about Samsung Galaxy Tab.)
author Eric Wing <ewing . public |-at-| gmail . com>
date Mon, 28 Mar 2011 16:05:25 -0700
parents 60500a33735a
children a554e41eeb13
files ALmixer.c
diffstat 1 files changed, 42 insertions(+), 12 deletions(-) [+]
line wrap: on
line diff
--- a/ALmixer.c	Mon Mar 28 15:16:26 2011 -0700
+++ b/ALmixer.c	Mon Mar 28 16:05:25 2011 -0700
@@ -223,6 +223,7 @@
 /* This is for a simple lock system. It is not meant to be good,
  * but just sufficient to minimize/avoid threading issues
  */
+static ALuint g_StreamThreadEnabled = 0;
 static SDL_mutex* s_simpleLock;
 static SDL_Thread* Stream_Thread_global = NULL;
 #endif /* ENABLE_ALMIXER_THREADS */
@@ -230,6 +231,7 @@
 static LinkedList* s_listOfALmixerData = NULL;
 
 /* Special stuff for iOS interruption handling */
+ALuint g_inInterruption = 0;
 static ALCcontext* s_interruptionContext = NULL;
 
 
@@ -6192,7 +6194,7 @@
 {
 	ALint retval;
 	
-	while(ALmixer_Initialized)
+	while(g_StreamThreadEnabled)
 	{
 		retval = Update_ALmixer(data);
 		/* 0 means that nothing needed updating and 
@@ -6773,7 +6775,7 @@
 		return AL_FALSE;
 	}
 		
-
+	g_StreamThreadEnabled = 1;
 	Stream_Thread_global = SDL_CreateThread(Stream_Data_Thread_Callback, NULL);
 	if(NULL == Stream_Thread_global)
 	{
@@ -6787,6 +6789,7 @@
 		alcCloseDevice(dev);
 		ALmixer_Initialized = 0;
 		Number_of_Channels_global = 0;
+		g_StreamThreadEnabled = 0;		
 		return AL_FALSE;
 	}
 	
@@ -7330,6 +7333,7 @@
 	}
 		
 
+	g_StreamThreadEnabled = 1;
 	Stream_Thread_global = SDL_CreateThread(Stream_Data_Thread_Callback, NULL);
 	if(NULL == Stream_Thread_global)
 	{
@@ -7340,6 +7344,7 @@
 		free(Source_Map_List);
 		ALmixer_Initialized = 0;
 		Number_of_Channels_global = 0;
+		g_StreamThreadEnabled = 0;
 		return AL_FALSE;
 	}
 
@@ -7360,8 +7365,21 @@
 
 void ALmixer_BeginInterruption()
 {
-#ifdef ENABLE_ALMIXER_THREADS
-	SDL_LockMutex(s_simpleLock);
+	if(1 == g_inInterruption)
+	{
+		return;
+	}
+#ifdef ENABLE_ALMIXER_THREADS
+	/* Kill bookkeeping thread to help minimize wasted CPU resources */
+
+	/* Is locking really necessary here? */
+/*	SDL_LockMutex(s_simpleLock); */
+	g_StreamThreadEnabled = 0;
+/*	SDL_UnlockMutex(s_simpleLock); */
+
+	SDL_WaitThread(Stream_Thread_global, NULL);
+	Stream_Thread_global = NULL;
+
 #endif
 	s_interruptionContext = alcGetCurrentContext();
 	if(NULL != s_interruptionContext)
@@ -7370,16 +7388,16 @@
 		alcSuspendContext(s_interruptionContext);
 		alcMakeContextCurrent(NULL);
 	}
-#ifdef ENABLE_ALMIXER_THREADS
-	SDL_UnlockMutex(s_simpleLock);
-#endif		
+
+	g_inInterruption = 1;
 }
 
 void ALmixer_EndInterruption()
 {
-#ifdef ENABLE_ALMIXER_THREADS
-	SDL_LockMutex(s_simpleLock);
-#endif
+	if(0 == g_inInterruption)
+	{
+		return;
+	}
 
 	/* Note: iOS, you need to set the AudioSession active.
 	 * But if the AudioSession is not initialized, this SetActive 
@@ -7403,8 +7421,15 @@
 		s_interruptionContext = NULL;
 	}
 #ifdef ENABLE_ALMIXER_THREADS
-	SDL_UnlockMutex(s_simpleLock);
-#endif
+	g_StreamThreadEnabled = 1;
+
+	Stream_Thread_global = SDL_CreateThread(Stream_Data_Thread_Callback, NULL);
+	if(NULL == Stream_Thread_global)
+	{
+		fprintf(stderr, "Critical Error: Could not create bookkeeping thread in EndInterruption\n");
+	}
+#endif
+	g_inInterruption = 0;
 }
 
 /* Keep the return value void to allow easy use with
@@ -7420,6 +7445,7 @@
 	{
 		return;
 	}
+
 #ifdef ENABLE_ALMIXER_THREADS
 	SDL_LockMutex(s_simpleLock);
 #endif
@@ -7457,8 +7483,12 @@
 	/* This flag will cause the thread to terminate */
 	ALmixer_Initialized = 0;
 #ifdef ENABLE_ALMIXER_THREADS
+	g_StreamThreadEnabled = 0;
 	SDL_UnlockMutex(s_simpleLock);
+	/* This is safe to call with NULL thread, so we don't need to do anything special for interruptions. */
 	SDL_WaitThread(Stream_Thread_global, NULL);
+	Stream_Thread_global = NULL;
+	g_inInterruption = 0;
 
 	SDL_DestroyMutex(s_simpleLock);
 #endif