"

 COPYRIGHT (c) 1993,2015 by Claus Gittinger

              All Rights Reserved

 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.

"

"{ Package: 'stx:libbasic' }"

"{ NameSpace: Smalltalk }"

WeakIdentityDictionary subclass:#Registry

	instanceVariableNames:''

	classVariableNames:''

	poolDictionaries:''

	category:'Collections-Weak'

!

!Registry class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1993,2015 by Claus Gittinger

              All Rights Reserved

 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.

"

!

documentation

"

    Registries provide an easy interface to using WeakArrays.

    A class, which wants to be informed of instance-death, can put a created object

    into a registry. The registry will create an executor, which is a (shallow-)copy

    of the object, and watch out for death of the original object. When it dies,

    the executor will be sent a #finalize message.

    The trick with the shallow copy is especially nice, you can think of it as

    being the original object which died.

    All objects, which keep external resources (such as fileDescriptors, fonts,

    colormap-entries etc.) should be registered, so that the underlying resource

    can be freed when the object goes away.

    Of course, you too can use it to do whatever you need to do in case of the

    death of an object.

    Registries use #executor to acquire the copy of the original,

    this can be redefined in individual classes for faster copying

    (typically, not all internal state, but only some device handles are needed for

    finalization). If the to-be-registered object is large, this method may also

    return a stub (placeHolder) object. (i.e. there is no need for the copy to be

    of the same class as the original, as long as it implements #finalize and frees

    the relevant OS resources. Some classes return a specialized private-class instance,

    which only holds on the handle and implements #finalize.)

    Example uses are found in Form, Color, ExternalStream and Font

    [author:]

        Claus Gittinger

    [see also:]

        WeakArray WeakIdentityDictionary

        Font Form Color Cursor ExternalStream

"

! !

!Registry methodsFor:'accessing'!

contents

    "return the collection of registered objects.

     Warning: this returns a weak collection."

    ^ self keys.

! !

!Registry methodsFor:'element disposal'!

clearDeadSlots

    |wasBlocked executors|

    "

     have to block here - dispose may be done at a low priority

     from the background finalizer. If new items are added by a

     higher prio process, the dictionary might get corrupted otherwise

    "

    wasBlocked := OperatingSystem blockInterrupts.

    [

        keyArray

            forAllDeadIndicesDo:[:idx |

                                    executors isNil ifTrue:[

                                        executors := OrderedCollection new.

                                    ].

                                    executors add:(valueArray basicAt:idx).

                                    valueArray basicAt:idx put:nil.

                                    tally := tally - 1.

                                ]

            replacingCorpsesWith:DeletedEntry.

    ] ensure:[

        wasBlocked ifFalse:[OperatingSystem unblockInterrupts].

        executors notNil ifTrue:[

            executors do:[:eachExecutor|

                [

                    self informDispose:eachExecutor.

                ] on:Error do:[:ex|

                    Logger error:'Error %1 during finalization of: %2' with:ex description with:eachExecutor.

                    ex suspendedContext fullPrintAllLevels:10.

                ].

            ].

        ].

    ].

!

informDispose:someHandle

    "send a dispose message - this is sent to the executor,

     since the original is already gone"

    someHandle finalize

!

update:something with:aParameter from:changedObject

    "an instance has been destroyed - look which one it was"

    something == #ElementExpired ifTrue:[

        self clearDeadSlots. 

        ^ self.

    ].

    something == #earlyRestart ifTrue:[

        self removeAll.

    ].

    super update:something with:aParameter from:changedObject.

    "Created: 15.6.1996 / 15:24:41 / cg"

    "Modified: 8.1.1997 / 14:05:02 / stefan"

    "Modified: 2.6.1997 / 18:15:23 / cg"

! !

!Registry methodsFor:'enumerating'!

detect:aBlock ifNone:exceptionValue

    keyArray validElementsDo:[:obj |

        (obj ~~ DeletedEntry and:[aBlock value:obj]) ifTrue:[^ obj].

    ].

    ^ exceptionValue value

!

do:aBlock

    "evaluate aBlock for each registered object"

    "#keysDo: would not work, since the keyArray instvar may change if

     elements are unregistered while looping."

    ^ keyArray validElementsDo:[:each|

        each ~~ DeletedEntry ifTrue:[aBlock value:each].

    ]

! !

!Registry methodsFor:'private'!

findKeyOrNil:key

    "Look for the key in the receiver.

     If it is found, return the index,

     otherwise the index of the first unused slot.

     Grow the receiver, if key was not found, and no unused slots were present.

     Warning: an empty slot MUST be filled by the sender - it is only to be sent

              by at:put: / add: - like methods.

     Redefined to not nil values of expired keys here."

    |index  "{ Class:SmallInteger }"

     length "{ Class:SmallInteger }"

     startIndex probe

     delIndex "{ Class:SmallInteger }"|

    (OperatingSystem blockInterrupts) ifFalse:[

        "/

        "/ may never be entered with interrupts enabled

        "/

        OperatingSystem unblockInterrupts.

        self error:'unblocked call of findKeyOrNil'.

    ].

    delIndex := 0.

    length := keyArray basicSize.

    startIndex := index := self initialIndexForKey:key.

    [

        probe := keyArray basicAt:index.

        key == probe ifTrue:[^ index].

        probe isNil ifTrue:[

            delIndex == 0 ifTrue:[^ index].

            keyArray basicAt:delIndex put:nil.

            ^ delIndex

        ].

        (delIndex == 0 and:[probe == DeletedEntry]) ifTrue:[

            delIndex := index

        ].

        index == length ifTrue:[

            index := 1

        ] ifFalse:[

            index := index + 1

        ].

        index == startIndex ifTrue:[

            delIndex ~~ 0 ifTrue:[

                keyArray basicAt:delIndex put:nil.

                ^ delIndex

            ].

            self grow.

            length := keyArray basicSize.

            startIndex := index := self initialIndexForKey:key.

        ].

    ] loop.

    "Modified: 30.1.1997 / 15:04:34 / cg"

    "Modified: 1.10.1997 / 11:25:32 / stefan"

! !

!Registry methodsFor:'registering objects'!

register:anObject

    "register anObject, so that a copy of it gets the disposed message

     when anObject dies (some time in the future)"

    |executor|

    executor := anObject executor.

    executor notNil ifTrue:[

        self register:anObject as:executor.

    ].

!

register:anObject as:aHandle

    "register anObject, so that I later receive informDispose: with aHandle

     (some time in the future)"

    aHandle isNil ifTrue:[

        self unregister:anObject.

        ^ self.

    ].

    self at:anObject put:aHandle.

!

registerChange:anObject

    "a registered object has changed, create a new executor"

    self register:anObject as:anObject executor.

!

unregister:anObject

    "remove registration of anObject, without telling the executor;

     should be sent, if we are no more interested in destruction of

     anObject (i.e. it no longer holds external resources)."

    self removeKey:anObject ifAbsent:[].

!

unregisterAllForWhich:aBlock

    "remove registration of all entries, for which the argument block

     evaluates to true.

     should be sent, if we are no more interested in destruction of

     a group of objects (i.e. it no longer holds external resources)."

    |wasBlocked any|

    wasBlocked := OperatingSystem blockInterrupts.

    keyArray validElementsDo:[:eachObject|

        (eachObject ~~ DeletedEntry and:[aBlock value:eachObject]) ifTrue:[

            self safeRemoveKey:eachObject.      

            any := true.

        ].

    ].

    any ifTrue:[ self possiblyShrink ].

    wasBlocked ifFalse:[OperatingSystem unblockInterrupts].

!

unregisterAllForWhichHandle:aBlock

    "remove registration of all handles, for which the argument block

     evaluates to true.

     should be sent, if we are no more interested in destruction of

     a group of objects (i.e. it no longer holds external resources)."

    |wasBlocked any|

    wasBlocked := OperatingSystem blockInterrupts.

    self keysAndValuesDo:[:eachObject :eachHandle|

        (eachObject class ~~ SmallInteger and:[aBlock value:eachHandle]) ifTrue:[

            self safeRemoveKey:eachObject.      

            any := true.

        ].

    ].

    any ifTrue:[ self possiblyShrink ].

    wasBlocked ifFalse:[OperatingSystem unblockInterrupts].

! !

!Registry class methodsFor:'documentation'!

version

    ^ '$Header$'

!

version_CVS

    ^ '$Header$'

! !