From b1938610dd285f7d339babdb95dee6958649fae0 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Mon, 20 Oct 2014 12:56:37 -0400
Subject: [PATCH] Revert "Use a semaphore to prevent us from having to busy
 wait on the audio buffer queue"

This reverts commit f3b3d2bd089508d1cf245b3447c50f981c2cd98e.
---
 Limelight/Connection.m | 23 ++---------------------
 1 file changed, 2 insertions(+), 21 deletions(-)

diff --git a/Limelight/Connection.m b/Limelight/Connection.m
index fe9c783..e275524 100644
--- a/Limelight/Connection.m
+++ b/Limelight/Connection.m
@@ -11,8 +11,6 @@
 #import <AudioUnit/AudioUnit.h>
 #import <AVFoundation/AVFoundation.h>
 
-#include <dispatch/dispatch.h>
-
 #include "Limelight.h"
 #include "opus.h"
 
@@ -42,7 +40,6 @@ struct AUDIO_BUFFER_QUEUE_ENTRY {
 static short decodedPcmBuffer[512];
 static NSLock *audioLock;
 static struct AUDIO_BUFFER_QUEUE_ENTRY *audioBufferQueue;
-static dispatch_semaphore_t audioQueueSemaphore;
 static int audioBufferQueueLength;
 static AudioComponentInstance audioUnit;
 static VideoDecoderRenderer* renderer;
@@ -94,8 +91,6 @@ void ArInit(void)
     opusDecoder = opus_decoder_create(48000, 2, &err);
     
     audioLock = [[NSLock alloc] init];
-    
-    audioQueueSemaphore = dispatch_semaphore_create(0);
 }
 
 void ArRelease(void)
@@ -140,15 +135,9 @@ void ArDecodeAndPlaySample(char* sampleData, int sampleLength)
                 // Clear all values from the buffer queue
                 struct AUDIO_BUFFER_QUEUE_ENTRY *entry;
                 while (audioBufferQueue != NULL) {
-                    // Unlink the current entry
                     entry = audioBufferQueue;
                     audioBufferQueue = entry->next;
-                    
-                    // Decrease the semaphore count and queue length
                     audioBufferQueueLength--;
-                    dispatch_semaphore_wait(audioQueueSemaphore, DISPATCH_TIME_NOW);
-                    
-                    // Free the entry
                     free(entry);
                 }
             }
@@ -163,13 +152,9 @@ void ArDecodeAndPlaySample(char* sampleData, int sampleLength)
                 }
                 lastEntry->next = newEntry;
             }
-            
-            // Increment the queue size and unlock
             audioBufferQueueLength++;
-            [audioLock unlock];
             
-            // Signal the other thread
-            dispatch_semaphore_signal(audioQueueSemaphore);
+            [audioLock unlock];
         }
     }
 }
@@ -333,13 +318,10 @@ static OSStatus playbackCallback(void *inRefCon,
             }
             
             // Wait for a buffer to be available
+            // FIXME: This needs optimization to avoid busy waiting for buffers
             struct AUDIO_BUFFER_QUEUE_ENTRY *audioEntry = NULL;
             while (audioEntry == NULL)
             {
-                // Wait for an entry to be present in the queue
-                dispatch_semaphore_wait(audioQueueSemaphore, DISPATCH_TIME_FOREVER);
-                
-                // If there's an entry there, dequeue it
                 [audioLock lock];
                 if (audioBufferQueue != NULL) {
                     // Dequeue this entry temporarily
@@ -368,7 +350,6 @@ static OSStatus playbackCallback(void *inRefCon,
                 audioBufferQueue = audioEntry;
                 audioBufferQueueLength++;
                 [audioLock unlock];
-                dispatch_semaphore_signal(audioQueueSemaphore);
             }
             else {
                 // This entry is fully depleted so free it