"

 COPYRIGHT (c) 1996-2015 by Claus Gittinger

 New code and modifications done at SWING Research Group [1]:

 COPYRIGHT (c) 2010-2015 by Jan Vrany, Jan Kurs and Marcel Hlopko

                            SWING Research Group, Czech Technical University in Prague

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

 [1] Code written at SWING Research Group contains a signature

     of one of the above copright owners. For exact set of such code,

     see the differences between this version and version stx:libjava

     as of 1.9.2010

"

"{ Package: 'stx:libjava' }"

"{ NameSpace: Smalltalk }"

Object subclass:#JavaMonitor

	instanceVariableNames:'owningProcess processesEntered monitorSema count waitingSema

		processesWaiting waitEnabled ownerPrintString'

	classVariableNames:'instVarAccess'

	poolDictionaries:''

	category:'Languages-Java-Support'

!

!JavaMonitor class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1996-2015 by Claus Gittinger

 New code and modifications done at SWING Research Group [1]:

 COPYRIGHT (c) 2010-2015 by Jan Vrany, Jan Kurs and Marcel Hlopko

                            SWING Research Group, Czech Technical University in Prague

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

 [1] Code written at SWING Research Group contains a signature

     of one of the above copright owners. For exact set of such code,

     see the differences between this version and version stx:libjava

     as of 1.9.2010

"

! !

!JavaMonitor class methodsFor:'initialization'!

initialize

    instVarAccess := RecursionLock forMutualExclusion.

    "Created: / 29-11-2011 / 11:23:56 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified (format): / 09-01-2013 / 16:10:10 / Jan Vrany <jan.vrany@fit.cvut.cz>"

! !

!JavaMonitor class methodsFor:'instance creation'!

for: owningObject

    ^ self basicNew initializeFor: owningObject.

    "Created: / 30-11-2011 / 20:39:55 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

for: owningObject thread: threadOrNil nestedLockCount: count

    ^ self basicNew initializeFor: owningObject thread: threadOrNil nestedLockCount: count

    "Created: / 26-08-2012 / 17:01:43 / Jan Vrany <jan.vrany@fit.cvut.cz>"

! !

!JavaMonitor methodsFor:'accessing'!

activeProcess

    ^ Processor activeProcess

!

copyProcessesEntered

    ^ processesEntered copy.

    "Created: / 20-11-2011 / 14:45:24 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

count

    ^ count

!

processesEntered

    "dont do anything to me, access needs to be sync'd"

    ^ processesEntered.

    "Created: / 20-11-2011 / 13:22:15 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

! !

!JavaMonitor methodsFor:'atomic'!

addProcess: aProcess 

    instVarAccess critical: [ processesEntered add: aProcess ].

    "Created: / 20-11-2011 / 20:30:07 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

clearOwningProcess

    instVarAccess critical: [ owningProcess := nil ].

    "Created: / 20-11-2011 / 20:34:27 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

decrement

    "owning process released monitor, let's lower our counter so we know how many times

     we have to release it"

    "/ the lock is probably not helping here to protect against problems with

    "/ increment/decrement:

    "/ the write-access (in reinitCounter) will be either done before incrementing/decrementing or after.

    "/ if after, everything is OK;

    "/ if before, the decremented value will be zero, which is probably wrong.

    "/ without the critical region, we might also get possible inconsistencies:

    "/ if written before, the counter will drop to zero

    "/ if written in-between, the counter will have the old value decremented;

    "/ if written afterwards, everything is OK.

    "/ so, the lock should be really elsewhere, making sure that noone will count

    "/ the monitor at-all and the monitor is reinitialized without anyone depending on the

    "/ count at all.

    "/ but then, no critical section is needed in reinitCounter!!.

    instVarAccess critical: [ count := count - 1 ].

    "Created: / 22-11-2011 / 10:49:33 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified (comment): / 19-06-2017 / 14:39:51 / mawalch"

!

disableWait

    JavaVM monitorTrace ifTrue:[

        Logger log: ('Waiting is disabled on monitor for %1' bindWith: ownerPrintString) severity:Logger severityDEBUG facility:#JVM.

    ].

    "/ critical region not needed here

    "/ instVarAccess critical: [ waitEnabled := false ].

    waitEnabled := false.

    "Created: / 30-11-2011 / 20:34:40 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified: / 02-03-2015 / 14:06:51 / Jan Vrany <jan.vrany@fit.cvut.cz>"

!

enableWait

    "/ critical region not needed here

    "/ instVarAccess critical: [waitEnabled := true].

    waitEnabled := true

    "Created: / 30-11-2011 / 20:34:31 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified (format): / 11-10-2013 / 11:17:58 / Jan Vrany <jan.vrany@fit.cvut.cz>"

!

increment

    "owning process entered monitor again (recursion ...), let's raise our counter so we know how many times

     we have to release it"

    "/ the lock is probably not helping here to protect against problems with

    "/ increment/decrement:

    "/ the write-access (in reinitCounter) will be either done before incrementing/decrementing or after.

    "/ if after, everything is OK;

    "/ if before, the decremented value will be zero, which is probably wrong.

    "/ without the critical region, we might also get possible inconsistencies:

    "/ if written before, the counter will drop to zero

    "/ if written in-between, the counter will have the old value decremented;

    "/ if written afterwards, everything is OK.

    "/ so, the lock should be really elsewhere, making sure that noone will count

    "/ the monitor at-all and the monitor is reinitialized without anyone depending on the

    "/ count at all.

    "/ but then, no critical section is needed in reinitCounter!!.

    instVarAccess critical: [ count := count + 1 ].

    "Created: / 22-11-2011 / 10:49:07 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified: / 27-08-2012 / 10:42:11 / Jan Vrany <jan.vrany@fit.cvut.cz>"

    "Modified (comment): / 19-06-2017 / 14:56:26 / mawalch"

!

owningProcess: aProcess 

    instVarAccess critical: [ owningProcess := aProcess ].

    "Created: / 20-11-2011 / 20:32:26 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

processesWaitingAdd: aProcess 

    instVarAccess 

        critical: [

            self assert: (processesWaiting includesKey: aProcess) not.

            processesWaiting at: aProcess put: count

        ].

    "Created: / 22-11-2011 / 11:57:50 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

processesWaitingRestore: aProcess 

    instVarAccess 

        critical: [

            self assert: (processesWaiting includesKey: aProcess).

            self reinitCounter: (processesWaiting at: aProcess).

            processesWaiting removeKey: aProcess

        ].

    "Created: / 22-11-2011 / 12:59:14 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

reinitCounter

    "owning process is different from previous, let's start counting from beginning"

    "/ the lock is probably not helping here to protect against problems with

    "/ increment/decrement:

    "/ the write-access here will be either done before incrementing/decrementing or after.

    "/ if after, everything is OK;

    "/ if before, the decremented value will be zero, which is probably wrong.

    "/ without the critical region, we might also get possible inconsistencies:

    "/ if written before, the counter will drop to zero

    "/ if written in-between, the counter will have the old value decremented;

    "/ if written afterwards, everything is OK.

    "/ so, the lock should be really elsewhere, making sure that noone will count

    "/ the monitor at-all and the monitor is reinitialized without anyone depending on the

    "/ count at all.

    "/ but then, no critical section is needed!!.

    instVarAccess critical: [ count := 1 ].

    "Created: / 22-11-2011 / 10:51:09 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified (comment): / 19-06-2017 / 14:56:31 / mawalch"

!

reinitCounter: newCount

    "/ the lock is probably not helping here to protect against problems with

    "/ increment/decrement:

    "/ the write-access here will be either done before incrementing/decrementing or after.

    "/ if after, everything is OK;

    "/ if before, the decremented value will be zero, which is probably wrong.

    "/ without the critical region, we might also get possible inconsistencies:

    "/ if written before, the counter will drop to zero

    "/ if written in-between, the counter will have the old value decremented;

    "/ if written afterwards, everything is OK.

    "/ so, the lock should be really elsewhere, making sure that noone will count

    "/ the monitor at-all and the monitor is reinitialized without anyone depending on the

    "/ count at all.

    "/ but then, no critical section is needed!!.

    instVarAccess critical: [ count := newCount ].

    "Created: / 22-11-2011 / 13:00:51 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified (comment): / 19-06-2017 / 14:56:35 / mawalch"

!

removeProcess: aProcess 

    instVarAccess 

        critical: [

            self assert: processesEntered last == aProcess.

            processesEntered remove: aProcess

        ].

    "Created: / 20-11-2011 / 20:28:37 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

waitEnabled

    "/ critical region not needed here

    "/ instVarAccess critical: [ ^ waitEnabled].

    ^ waitEnabled.

    "Created: / 30-11-2011 / 20:34:56 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

! !

!JavaMonitor methodsFor:'initialization'!

initialize

    "Q: is this ever called?"

    owningProcess := nil.

    processesEntered := OrderedCollection new.

    monitorSema := Semaphore new: 1.

    processesWaiting := Dictionary new.

    waitingSema := Semaphore new: 0.

    waitEnabled := true.

    "Created: / 20-11-2011 / 13:28:28 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

initializeFor: owningObject

    self initializeFor: owningObject thread: 0 nestedLockCount: 0.

    "Created: / 30-11-2011 / 20:39:31 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified: / 26-08-2012 / 17:25:55 / Jan Vrany <jan.vrany@fit.cvut.cz>"

!

initializeFor:owningObject thread:threadId nestedLockCount:cnt 

"/    self assert: (owningObject isJavaObject or:[owningObject isJavaClass]).

    processesEntered := OrderedCollection new.

    waitEnabled := true.

    processesWaiting := Dictionary new.

    waitingSema := Semaphore new:0.

    ownerPrintString := owningObject class name , '@' , owningObject identityHash printString.

    "/Not locked...    

    threadId == 0 ifTrue:[

        monitorSema := Semaphore new:1.

        count := 0.

        ^self.

    ] ifFalse: [

        "threadId is not zero (zero is threadId of scheduler process, which will never try to acquire the monitor)"

        "so it means it is possible that the thin lock is already locked for other thread, we must be careful " 

        owningProcess := ObjectMemory processesKnownInVM detect:[:p|p id == threadId] ifNone:[nil].

        self assert: owningProcess notNil.

        processesEntered add: owningProcess.  

        cnt timesRepeat:[

"/            JavaVM enteredMonitorsOf:  owningProcess add: owningObject.

"/            JavaVM acquiredMonitorsOf: owningProcess add: owningObject.

        ].

        monitorSema := Semaphore new: 0.

        count := cnt.

    ].

    "Created: / 26-08-2012 / 17:02:29 / Jan Vrany <jan.vrany@fit.cvut.cz>"

! !

!JavaMonitor methodsFor:'public'!

acquire

    | thisProcess |

    thisProcess := self activeProcess.

    (self isOwnedBy: thisProcess) ifTrue: [

        self increment.

        ^ self

    ].

    monitorSema wait.

    self owningProcess: thisProcess.

    count := 1.

    "Created: / 20-11-2011 / 13:21:46 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified: / 27-08-2012 / 11:45:46 / Jan Vrany <jan.vrany@fit.cvut.cz>"

!

enter

    | thisProcess |

    thisProcess := self activeProcess.

    self addProcess: thisProcess.

    self acquire.

    "Created: / 20-11-2011 / 13:21:42 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

exit

    | thisProcess |

    thisProcess := self activeProcess.

    (self isOwnedBy: thisProcess) ifTrue: [ self release. ].    

    processesEntered remove: thisProcess ifAbsent: nil.

    "Created: / 20-11-2011 / 13:21:54 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified: / 26-08-2012 / 19:54:14 / Jan Vrany <jan.vrany@fit.cvut.cz>"

!

notify

    "wakeup one waiting process"

    | thisProcess |

    thisProcess := Processor activeProcess.

    self assert: (self isOwnedBy: thisProcess).

    JavaVM monitorTrace ifTrue:[

        Logger 

            log: ('%1: notifying %2 processes' bindWith: thisProcess printString

                    with: processesWaiting size)

            severity: Logger severityDEBUG

            facility: #JVM.

    ].

    waitingSema signal.

    Processor yield.

    "Created: / 22-11-2011 / 12:14:23 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified: / 02-03-2015 / 14:06:43 / Jan Vrany <jan.vrany@fit.cvut.cz>"

!

notifyAll

    "wakeup one waiting process"

    | thisProcess |

    thisProcess := Processor activeProcess.

    self assert: (self isOwnedBy: thisProcess).

    JavaVM monitorTrace ifTrue:[

        Logger 

            log: ('%1: notifying all %2 processes' bindWith: thisProcess printString

                    with: processesWaiting size)

            severity: Logger severityDEBUG

            facility: #JVM.

    ].

    waitingSema signalForAll.

    Processor yield.

    "Created: / 22-11-2011 / 12:14:36 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified: / 02-03-2015 / 14:06:37 / Jan Vrany <jan.vrany@fit.cvut.cz>"

!

release

    self assert: (self isOwnedBy: owningProcess).

    count == 1 ifTrue: [

        self clearOwningProcess.

        count := 0.

        monitorSema signal.

    ] ifFalse: [

        self decrement.       

    ]

    "Created: / 20-11-2011 / 13:21:52 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified: / 11-10-2013 / 11:18:21 / Jan Vrany <jan.vrany@fit.cvut.cz>"

!

releaseAll

    count timesRepeat: [self release].

    "Created: / 22-11-2011 / 13:05:20 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

wait

    "make owning process to go to wait"

    self waitForMilliseconds: nil.

    "Created: / 22-11-2011 / 11:57:56 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

waitForMilliseconds: timeOut 

    "make owning process to go to wait, but not longer than timeout"

    | thisProcess countBeforeWait |

    thisProcess := Processor activeProcess.

    self assert: (self isOwnedBy: thisProcess).

    self waitEnabled ifFalse: [

        JavaVM monitorTrace ifTrue:[

            Logger 

                log: ('%1 wanted to go to sleep, but it cant, this monitor is for %2 which is already dead' 

                        bindWith: thisProcess printString

                        with: ownerPrintString)

                severity: Logger severityDEBUG

                facility: #JVM.

        ].

        ^ self.

    ].

    JavaVM monitorTrace ifTrue:[

        Logger 

            log: ('%1 is going to wait on %3 for timeout: %2' 

                    bindWith: thisProcess printString

                    with: timeOut

                    with: ownerPrintString printString)

            severity: #debug

            facility: #JVM.

    ].

    self processesWaitingAdd: thisProcess.

    countBeforeWait :=  count.

    self releaseAll.

     "JV@2011-11-25: zero timeout means wait without timeout!!!!!!"

    timeOut == 0 ifTrue: [ waitingSema wait ] ifFalse: [

        waitingSema waitWithTimeoutMs: timeOut

    ].

    JavaVM monitorTrace ifTrue:[ 

        Logger 

            log: ('%1 has been notified and is trying to acquire monitor for %2 which is owned by %3' 

                    bindWith: thisProcess printString with: ownerPrintString printString with: owningProcess printString)

            severity: #debug

            facility: #JVM.

    ].

    self acquire.

    count := countBeforeWait.

    self processesWaitingRestore: thisProcess.

    "Created: / 22-11-2011 / 12:52:45 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified: / 01-12-2011 / 10:57:52 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

    "Modified: / 02-03-2015 / 14:06:33 / Jan Vrany <jan.vrany@fit.cvut.cz>"

! !

!JavaMonitor methodsFor:'queries'!

isAcquired

    ^ instVarAccess critical: [ owningProcess notNil ].

    "Created: / 20-11-2011 / 13:22:26 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

!

isOwnedBy: aProcess 

    ^ instVarAccess critical: [ owningProcess == aProcess ].

    "Created: / 20-11-2011 / 13:23:14 / Marcel Hlopko <hlopkmar@fel.cvut.cz>"

! !

!JavaMonitor class methodsFor:'documentation'!

version