bk commit into 6.0-falcon tree (jas:1.2592)

[U-ROWVWADEjas]

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6.0-falcon repository of . When  does a push these changes will
be propagated to the main repository and, within 24 hours after the
push, to the public repository.
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ChangeSet@stripped, 2007-07-06 10:20:14-04:00, jas@rowvwade. +1 -0
  Optimized SyncObject.

  storage/falcon/SyncObject.cpp@stripped, 2007-07-06 10:19:56-04:00, jas@rowvwade. +51 -26
    Optimized SyncObject.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	jas
# Host:	rowvwade.
# Root:	D:/MySQL/mysql-5.1-falcon

--- 1.33/storage/falcon/SyncObject.cpp	2007-07-06 10:20:36 -04:00
+++ 1.34/storage/falcon/SyncObject.cpp	2007-07-06 10:20:36 -04:00
@@ -48,6 +48,11 @@
 
 //#define STALL_THRESHOLD	1000
 
+#define BACKOFF	\
+		if (thread)\
+			thread->sleep(1);\
+		else\
+			thread = Thread::getThread("SyncObject::lock")
 
 #ifdef TRACE_SYNC_OBJECTS
 
@@ -150,10 +155,7 @@
 			if (COMPARE_EXCHANGE(&lockState, oldState, newState))
 				return;
 			
-			if (thread)
-				thread->sleep(1);
-			else
-				thread = Thread::getThread("SyncObject::lock");
+			BACKOFF;
 			}
 
 		mutex.lock();
@@ -176,10 +178,7 @@
 				return;
 				}
 
-			if (thread)
-				thread->sleep(1);
-			else
-				thread = Thread::getThread("SyncObject::lock");
+			BACKOFF;
 			}
 
 		thread = Thread::getThread("SyncObject::lock");
@@ -221,10 +220,7 @@
 				return; 
 				}
 			
-			if (thread)
-				thread->sleep(1);
-			else
-				thread = Thread::getThread("SyncObject::lock");
+			BACKOFF;
 			}
 			
 		mutex.lock();
@@ -247,10 +243,7 @@
 				return;
 				}
 			
-			if (thread)
-				thread->sleep(1);
-			else
-				thread = Thread::getThread("SyncObject::lock");
+			BACKOFF;
 			}
 		}
 
@@ -268,7 +261,8 @@
 
 		return;
 		}
-		
+	
+	/***	
 	Thread *thread = NULL;
 	
 	for (;;)
@@ -291,6 +285,23 @@
 		else
 			thread = Thread::getThread("SyncObject::lock");
 		}
+	***/
+
+	exclusiveThread = NULL;
+	
+	if (type == Shared)
+		{
+		ASSERT(lockState > 0);
+		INTERLOCKED_DECREMENT(lockState);
+		}
+	else
+		{
+		ASSERT(lockState == -1);
+		INTERLOCKED_INCREMENT(lockState);
+		}
+	
+	if (waiters)
+		grantLocks();
 }
 
 void SyncObject::downGrade(LockType type)
@@ -302,6 +313,8 @@
 	for (;;)
 		if (COMPARE_EXCHANGE(&lockState, -1, 1))
 			{
+			exclusiveThread = NULL;
+			
 			if (waiters)
 				grantLocks();
 				
@@ -431,14 +444,19 @@
 
 void SyncObject::bumpWaiters(int delta)
 {
-	for (;;)
-		{
-		INTERLOCK_TYPE oldValue = waiters;
-		INTERLOCK_TYPE newValue = waiters + delta;
-		
-		if (COMPARE_EXCHANGE(&waiters, oldValue, newValue))
-			return;
-		}
+	if (delta == 1)
+		INTERLOCKED_INCREMENT(waiters);
+	else if (delta == -1)
+		INTERLOCKED_DECREMENT(waiters);
+	else
+		for (;;)
+			{
+			INTERLOCK_TYPE oldValue = waiters;
+			INTERLOCK_TYPE newValue = waiters + delta;
+			
+			if (COMPARE_EXCHANGE(&waiters, oldValue, newValue))
+				return;
+			}
 }
 
 void SyncObject::grantLocks(void)
@@ -446,7 +464,8 @@
 	mutex.lock();
 	ASSERT ((waiters && que) || (!waiters && !que));
 	const char *description = NULL;
-
+	Thread *thread = NULL;
+	
 	for (Thread *thread = que, *prior = NULL, *next; thread; thread = next)
 		{
 		description = thread->description;
@@ -464,18 +483,24 @@
 					exclusiveThread = NULL;
 					break;
 					}
+				
+				BACKOFF;
 				}
 		else
 			{
 			ASSERT(thread->lockType == Exclusive);
 			
 			while (lockState == 0)
+				{
 				if (COMPARE_EXCHANGE(&lockState, 0, -1))
 					{
 					granted = true;
 					exclusiveThread = thread;
 					break;
 					}
+				
+				BACKOFF;
+				}
 			}
 		
 		if (granted)