Re: [squeak-dev] The Trunk: Kernel-ar.238.mcz

> Andreas Raab uploaded a new version of Kernel to project The Trunk:
> http://source.squeak.org/trunk/Kernel-ar.238.mcz
>
> ==================== Summary ====================
>
> Name: Kernel-ar.238
> Author: ar
> Time: 3 September 2009, 9:50:51 am
> UUID: 9896c3f8-760f-e942-ac84-5f6c9127150c
> Ancestors: Kernel-ar.237
>
> http://bugs.squeak.org/view.php?id=7321
>
> Change Set:             AtomicProcessSuspend
> Date:                   23 March 2009
> Author:                 Andreas Raab
>
> In-image support for atomic process suspend.
>
> =============== Diff against Kernel-ar.237 ===============
>
> Item was changed:
>  ----- Method: Process>>suspend (in category 'changing process state') -----
>  suspend
> +       "Primitive. Stop the process that the receiver represents in such a way
> -       "Stop the process that the receiver represents in such a way
>        that it can be restarted at a later time (by sending the receiver the
>        message resume). If the receiver represents the activeProcess, suspend it.
> +       Otherwise remove the receiver from the list of waiting processes.
> +       The return value of this method is the list the receiver was previously on (if any)."
> +       | oldList |
> +       <primitive: 88>
> +       "This is fallback code for VMs which only support the old primitiveSuspend which
> +       would not accept processes that are waiting to be run."
> +       myList ifNil:[^nil]. "this allows us to use suspend multiple times"
> +       oldList := myList.
> +       myList := nil.
> +       oldList remove: self ifAbsent:[].
> +       ^oldList!
> -       Otherwise remove the receiver from the list of waiting processes."
> -
> -       self isActiveProcess ifTrue: [
> -               myList := nil.
> -               self primitiveSuspend.
> -       ] ifFalse: [
> -               myList ifNotNil: [
> -                       myList remove: self ifAbsent: [].
> -                       myList := nil].
> -       ]
> - !
>
> Item was changed:
>  ----- Method: Process>>offList (in category 'accessing') -----
>  offList
> +       "OBSOLETE. Process>>suspend will atomically reset myList if the process is suspended.
> +       There should never be a need to send #offList but some older users may not be aware
> +       of the changed semantics to suspend and may try the old hickadidoo seen here:
> -       "Inform the receiver that it has been taken off a list that it was
> -       suspended on. This is to break a backpointer."
>
> +               (suspendingList := process suspendingList) == nil
> +                       ifTrue: [process == Processor activeProcess ifTrue: [process suspend]]
> +                       ifFalse: [suspendingList remove: process ifAbsent:[].
> +                                       process offList].
> +
> +       Usages like the above should be replaced by a simple 'process suspend' "
>        myList := nil!
>
> Item was changed:
>  ----- Method: Process>>terminate (in category 'changing process state') -----
>  terminate
>        "Stop the process that the receiver represents forever.  Unwind to execute pending ensure:/ifCurtailed: blocks before terminating."
>
> +       | ctxt unwindBlock oldList |
> -       | ctxt unwindBlock inSema |
>        self isActiveProcess ifTrue: [
>                ctxt := thisContext.
>                [       ctxt := ctxt findNextUnwindContextUpTo: nil.
>                        ctxt isNil
>                ] whileFalse: [
>                        unwindBlock := ctxt tempAt: 1.
>                        unwindBlock ifNotNil: [
>                                ctxt tempAt: 1 put: nil.
>                                thisContext terminateTo: ctxt.
>                                unwindBlock value].
>                ].
>                thisContext terminateTo: nil.
> +               self suspend.
> +       ] ifFalse:[
> +               myList ifNotNil:[oldList := self suspend].
> +               suspendedContext ifNotNil:[
> -               myList := nil.
> -               self primitiveSuspend.
> -       ] ifFalse: [
> -               "Since the receiver is not the active process, drop its priority to rock-bottom so that
> -               it doesn't accidentally preempt the process that is trying to terminate it."
> -               priority := 10.
> -               myList ifNotNil: [
> -                       myList remove: self ifAbsent: [].
> -                       "Figure out if the receiver was terminated while waiting on a Semaphore"
> -                       inSema := myList class == Semaphore.
> -                       myList := nil].
> -               suspendedContext ifNotNil: [
>                        "Figure out if we are terminating the process while waiting in Semaphore>>critical:
>                        In this case, pop the suspendedContext so that we leave the ensure: block inside
>                        Semaphore>>critical: without signaling the semaphore."
> +                       (oldList class == Semaphore and:[
> -                       (inSema == true and:[
>                                suspendedContext method == (Semaphore compiledMethodAt: #critical:)]) ifTrue:[
>                                        suspendedContext := suspendedContext home.
>                        ].
>                        ctxt := self popTo: suspendedContext bottomContext.
>                        ctxt == suspendedContext bottomContext ifFalse: [
>                                self debug: ctxt title: 'Unwind error during termination']].
>        ].
>  !
>
> Item was removed:
> - ----- Method: Process>>primitiveSuspend (in category 'changing process state') -----
> - primitiveSuspend
> -       "Primitive. Stop the process that self represents in such a way
> -       that it can be restarted at a later time (by sending #resume).
> -       ASSUMES self is the active process.
> -       Essential. See Object documentation whatIsAPrimitive."
> -
> -       <primitive: 88>
> -       self primitiveFailed!
>
>
>

> Andreas Raab uploaded a new version of Kernel to project The Trunk:
> http://source.squeak.org/trunk/Kernel-ar.238.mcz
>
> ==================== Summary ====================
>
> Name: Kernel-ar.238
> Author: ar
> Time: 3 September 2009, 9:50:51 am
> UUID: 9896c3f8-760f-e942-ac84-5f6c9127150c
> Ancestors: Kernel-ar.237
>
> http://bugs.squeak.org/view.php?id=7321
>
> Change Set: AtomicProcessSuspend
> Date: 23 March 2009
> Author: Andreas Raab
>
> In-image support for atomic process suspend.
>
> =============== Diff against Kernel-ar.237 ===============
>
> Item was changed:
>   ----- Method: Process>>suspend (in category 'changing process state')
> -----
>   suspend
> + "Primitive. Stop the process that the receiver represents in such a way
> - "Stop the process that the receiver represents in such a way
>   that it can be restarted at a later time (by sending the receiver the
>   message resume). If the receiver represents the activeProcess, suspend
> it.
> + Otherwise remove the receiver from the list of waiting processes.
> + The return value of this method is the list the receiver was previously
> on (if any)."
> + | oldList |
> + <primitive: 88>
> + "This is fallback code for VMs which only support the old
> primitiveSuspend which
> + would not accept processes that are waiting to be run."
> + myList ifNil:[^nil]. "this allows us to use suspend multiple times"
> + oldList := myList.
> + myList := nil.
> + oldList remove: self ifAbsent:[].
> + ^oldList!
> - Otherwise remove the receiver from the list of waiting processes."
> -
> - self isActiveProcess ifTrue: [
> - myList := nil.
> - self primitiveSuspend.
> - ] ifFalse: [
> - myList ifNotNil: [
> - myList remove: self ifAbsent: [].
> - myList := nil].
> - ]
> - !
>
> Item was changed:
>   ----- Method: Process>>offList (in category 'accessing') -----
>   offList
> + "OBSOLETE. Process>>suspend will atomically reset myList if the process
> is suspended.
> + There should never be a need to send #offList but some older users may
> not be aware
> + of the changed semantics to suspend and may try the old hickadidoo seen
> here:
> - "Inform the receiver that it has been taken off a list that it was
> - suspended on. This is to break a backpointer."
>
> + (suspendingList := process suspendingList) == nil
> + ifTrue: [process == Processor activeProcess ifTrue: [process suspend]]
> + ifFalse: [suspendingList remove: process ifAbsent:[].
> + process offList].
> +
> + Usages like the above should be replaced by a simple 'process suspend' "
>   myList := nil!
>
> Item was changed:
>   ----- Method: Process>>terminate (in category 'changing process state')
> -----
>   terminate
>   "Stop the process that the receiver represents forever.  Unwind to
> execute pending ensure:/ifCurtailed: blocks before terminating."
>
> + | ctxt unwindBlock oldList |
> - | ctxt unwindBlock inSema |
>   self isActiveProcess ifTrue: [
>   ctxt := thisContext.
>   [ ctxt := ctxt findNextUnwindContextUpTo: nil.
>   ctxt isNil
>   ] whileFalse: [
>   unwindBlock := ctxt tempAt: 1.
>   unwindBlock ifNotNil: [
>   ctxt tempAt: 1 put: nil.
>   thisContext terminateTo: ctxt.
>   unwindBlock value].
>   ].
>   thisContext terminateTo: nil.
> + self suspend.
> + ] ifFalse:[
> + myList ifNotNil:[oldList := self suspend].
> + suspendedContext ifNotNil:[
> - myList := nil.
> - self primitiveSuspend.
> - ] ifFalse: [
> - "Since the receiver is not the active process, drop its priority to
> rock-bottom so that
> - it doesn't accidentally preempt the process that is trying to terminate
> it."
> - priority := 10.

>> - ] ifFalse: [
>> - "Since the receiver is not the active process, drop its priority to
>> rock-bottom so that
>> - it doesn't accidentally preempt the process that is trying to terminate
>> it."
>> - priority := 10.
>
> I admit not fully understanding everything here, but should you
> perhaps have kept the priority drop here? Otherwise, by my
> understanding, the process that is meant to be terminated might be
> restarted in this line here before it gets suspended:
>
>> + myList ifNotNil:[oldList := self suspend].