medfall

commit 7e30adcbc9f27d53dc5bb4f05c2944aaa36356c5
parent 6c14d970d9a78d434be65479582364045c977598
Author: Michael Savage <mikejsavage@gmail.com>
Date:   Fri Sep  2 15:51:25 -0700

Add enqueue_spin for nonblocking queues

Diffstat:
mixer.cc
 | 
6
+++---
queue.h
 | 
16
++++++++++++++++
2 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/mixer.cc b/mixer.cc
@@ -219,18 +219,18 @@ void mixer_volume( PlayingSoundID sound_id, float volume ) {
 	cmd.type = MIXER_VOLUME;
 	cmd.sound_id = sound_id;
 	cmd.volume = clamp01( volume );
-	while( !command_queue.enqueue( cmd ) );
+	command_queue.enqueue_spin( cmd );
 }
 
 void mixer_stop( PlayingSoundID sound_id ) {
 	MixerCommand cmd;
 	cmd.type = MIXER_STOP;
 	cmd.sound_id = sound_id;
-	while( !command_queue.enqueue( cmd ) );
+	command_queue.enqueue_spin( cmd );
 }
 
 void mixer_stop_all() {
 	MixerCommand cmd;
 	cmd.type = MIXER_STOP_ALL;
-	while( !command_queue.enqueue( cmd ) );
+	command_queue.enqueue_spin( cmd );
 }
diff --git a/queue.h b/queue.h
@@ -1,6 +1,8 @@
 #ifndef _QUEUE_H_
 #define _QUEUE_H_
 
+#include "platform_thread.h"
+
 template< typename T >
 struct BlockingQueue {
 	virtual void enqueue( const T & x ) = 0;
@@ -15,12 +17,26 @@ struct BlockingQueue {
 
 };
 
+const int ATTEMPTS_BEFORE_YIELD = 128;
+
 template< typename T >
 struct NonblockingQueue {
 	virtual bool enqueue( const T & x ) = 0;
 	virtual T * dequeue_acquire() = 0;
 	virtual void dequeue_release() = 0;
 
+	void enqueue_spin( const T & x ) {
+		int attempt = 0;
+		while( !enqueue( x ) ) {
+			if( attempt < ATTEMPTS_BEFORE_YIELD ) {
+				attempt++;
+			}
+			else {
+				thread_yield();
+			}
+		}
+	}
+
 	bool dequeue( T * x ) {
 		T * t = dequeue_acquire();
 		if( t == NULL ) return false;