Fix for logic to handle termination of process which waits for the lock

Author: dionisiydk

ReadWriteLock-Tests.package/ReadWriteLockTests.class/instance/testTerminatingReadWhichWaitingWriteAndAnotherRead.st

@@ -18,6 +18,9 @@ testTerminatingReadWhichWaitingWriteAndAnotherRead
 	self passForkedProcesses.
 	lastReaderExecuted should be: false.
 	secondReader terminate.
+	
+	self passForkedProcesses. "Now last read should be still locked"
+	lastReaderExecuted should be: false.
 	writeSemaphore signal.
 	self waitForkedProcesses.
 	lastReaderExecuted should be: true.

ReadWriteLock.package/PrimitiveLock.class/instance/handleProcessTerminationOfWaitingContext..st

@@ -7,18 +7,15 @@ This method called from Process>>terminate when it detects waiting me. My users
 		ensure: [ releaseNotRequired ifFalse: [ lock release ] ]
 This code is not working correctly by itself. When current process waits on 'lock acquire' somebody can terminate it and ensure will release me which shoud not happens in this case. But if I was acquired but process is just suspended on 'lock acquire' then process termination should execute ensure block to release me.  
 This problem solved by this special method. Process>>terminate detects first case and inject right value for tracking variable.  Senders should mark method with special pragma 
-<lockAt: #lockVariableName tracksStateAt: 1> 'index of local variable'
-Method can contain mulpible pragmas for referenced locks. (ReadWriteLock for example needs this).
-"
-	| receiver lockFlagIndex |
+<lockAt: #lockVariableName tracksStateAt: #tempName> 'var name which keeps the lock state'
+Method can contain multiple pragmas for referenced locks. (ReadWriteLock for example needs this)"
+	| receiver |
 	receiver := suspendedContext receiver.
 
-	suspendedContext method pragmas do: [ :pragma | 
-		
+	suspendedContext method pragmas do: [ :pragma | 		
 		pragma keyword == #lockAt:tracksStateAt: ifTrue: [ 
 			(receiver readSlotNamed: pragma arguments first) == self ifTrue: [ 
-				lockFlagIndex := pragma arguments last.
-				suspendedContext home namedTempAt: lockFlagIndex put: true
+				self resetLockFlag: pragma arguments last in: suspendedContext home.
 			 ]
 		]
 	 ].

ReadWriteLock.package/PrimitiveLock.class/instance/resetLockFlag.in..st

@@ -0,0 +1,4 @@
+process termination handling
+resetLockFlag: flagTempName in: criticalContext
+	
+	criticalContext debuggerMap tempNamed: flagTempName in: criticalContext put: true

ReadWriteLock.package/ReadWriteLock.class/instance/criticalRead..st

@@ -7,8 +7,8 @@ criticalRead: aBlock
 	Given block is safe for recursive read/write sections
 "
 	| readLockAcquiredNotHere newReadersCount  writeLockAcquiredNotHere readingPrepared writeLockWasAsked |
-	<lockAt: #readLock tracksStateAt: 1>
-	<lockAt: #writeLock tracksStateAt: 3>
+	<lockAt: #readLock tracksStateAt: #readLockAcquiredNotHere>
+	<lockAt: #writeLock tracksStateAt: #writeLockAcquiredNotHere>
 
 	readLockAcquiredNotHere := true.
 	writeLockAcquiredNotHere := true.
@@ -26,9 +26,10 @@ criticalRead: aBlock
 	readingPrepared := true.
 	readLockAcquiredNotHere := true.
 	readLock release] ifCurtailed: [
+
 		newReadersCount ifNotNil: [ currentReaders := newReadersCount - 1 ]. "we should restore previous value because we can't prepare reading (process was terminated)"
 		readLockAcquiredNotHere ifFalse: [readLock release].
-		writeLockAcquiredNotHere ifFalse: [ writeLock release]].		
+		writeLockAcquiredNotHere ifFalse: [writeLock release]].		
 	^aBlock value] ensure: [ 
 		readingPrepared ifTrue: [ 
 			readLock acquire.

ReadWriteLock.package/ReadWriteLock.class/instance/criticalWrite..st

@@ -7,7 +7,7 @@ criticalWrite: aBlock
 	Given block is safe for recursive read/write sections
 "
 	| lockAcquiredNotHere |
-	<lockAt: #writeLock tracksStateAt: 1>
+	<lockAt: #writeLock tracksStateAt: #lockAcquiredNotHere>
 
 	lockAcquiredNotHere := true.