X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=mpmc-queue%2Fmpmc-queue.h;h=fa5f37a1cf054634bdb4d9c152ef7299ed7f6b63;hb=1438eb7c0715e53611a717e593bfa3fe1bd30588;hp=dc2b5618771774238c1c16f97efa87262da182a4;hpb=9f2a28f12f61001be2bd5adc74964acf5e8e6721;p=model-checker-benchmarks.git

diff --git a/mpmc-queue/mpmc-queue.h b/mpmc-queue/mpmc-queue.h
index dc2b561..fa5f37a 100644
--- a/mpmc-queue/mpmc-queue.h
+++ b/mpmc-queue/mpmc-queue.h
@@ -27,6 +27,8 @@ public:
 	//-----------------------------------------------------
 
 	t_element * read_fetch() {
+		// FIXME: We can have a relaxed for sure here since the next CAS
+		// will fix the problem
 		unsigned int rdwr = m_rdwr.load(mo_acquire);
 		unsigned int rd,wr;
 		for(;;) {
@@ -34,10 +36,12 @@ public:
 			wr = rdwr & 0xFFFF;
 
 			if ( wr == rd ) // empty
-				return false;
-
+				return NULL;
+	
 			if ( m_rdwr.compare_exchange_weak(rdwr,rdwr+(1<<16),mo_acq_rel) )
 				break;
+			else
+				thrd_yield();
 		}
 
 		// (*1)
@@ -58,6 +62,8 @@ public:
 	//-----------------------------------------------------
 
 	t_element * write_prepare() {
+		// FIXME: We can have a relaxed for sure here since the next CAS
+		// will fix the problem
 		unsigned int rdwr = m_rdwr.load(mo_acquire);
 		unsigned int rd,wr;
 		for(;;) {
@@ -69,6 +75,8 @@ public:
 
 			if ( m_rdwr.compare_exchange_weak(rdwr,(rd<<16) | ((wr+1)&0xFFFF),mo_acq_rel) )
 				break;
+			else
+				thrd_yield();
 		}
 
 		// (*1)