Life -cycle of active objects

diff -r 51a74ef9ed63 -r ae94777fff8f Symbian3/SDK/Source/GUID-E61A931D-6E66-5E17-AE61-ABFB74CB8EF2.dita --- a/Symbian3/SDK/Source/GUID-E61A931D-6E66-5E17-AE61-ABFB74CB8EF2.dita Wed Mar 31 11:11:55 2010 +0100 +++ b/Symbian3/SDK/Source/GUID-E61A931D-6E66-5E17-AE61-ABFB74CB8EF2.dita Fri Jun 11 12:39:03 2010 +0100 @@ -1,52 +1,52 @@ - - - - - -Life -cycle of active objectsThis document describes the life cycle of an active objet. -

The diagram illustrates the life-cycle of an active object.

- -Flow diagram showing the life cycle of an active object - - -

Procedural flow follows the black arrows; control is transferred along -the blue links, as follows:

the main program creates -and installs an active scheduler
active objects are created; -their constructors ensure that every active object is added to the active -scheduler (which keeps a reference to the object in its queue)
an active object is -called to issue an initial request. This sets the object's iActive true -(indicating a request was issued but not yet completed) and schedules the -underlying service, which sets the object's iStatus to KRequestPending. -(If this step is omitted, no service will be requested, so no handler will -be invoked and hence the active scheduler will wait forever in its loop, never -calling any object's RunL())
the active scheduler -is started. This now takes over; control is only returned to the main program -for termination when the active scheduler is stopped
when a requested service -completes, it's handler terminates by signaling service completion; this alters -the associated active object's iStatus
when any service handler -signals completion, the active scheduler tests each object in its queues for -one with iActive true (request not completed) and iStatus not -set to KRequestPending (i.e. the request has been handled)
if the active scheduler -finds an object with the above conditions, it sets iActive false -and calls the object's RunL()
the RunL() may -reschedule the request (so that the handler is again invoked when the requested -service completes and the cycle continues.) or may stop the active scheduler, -returning control to the main program for termination.

+ + + + + +Life +cycle of active objectsThis document describes the life cycle of an active objet. +

The diagram illustrates the life-cycle of an active object.

+ +Flow diagram showing the life cycle of an active object + + +

Procedural flow follows the black arrows; control is transferred along +the blue links, as follows:

the main program creates +and installs an active scheduler
active objects are created; +their constructors ensure that every active object is added to the active +scheduler (which keeps a reference to the object in its queue)
an active object is +called to issue an initial request. This sets the object's iActive true +(indicating a request was issued but not yet completed) and schedules the +underlying service, which sets the object's iStatus to KRequestPending. +(If this step is omitted, no service will be requested, so no handler will +be invoked and hence the active scheduler will wait forever in its loop, never +calling any object's RunL())
the active scheduler +is started. This now takes over; control is only returned to the main program +for termination when the active scheduler is stopped
when a requested service +completes, it's handler terminates by signaling service completion; this alters +the associated active object's iStatus
when any service handler +signals completion, the active scheduler tests each object in its queues for +one with iActive true (request not completed) and iStatus not +set to KRequestPending (i.e. the request has been handled)
if the active scheduler +finds an object with the above conditions, it sets iActive false +and calls the object's RunL()
the RunL() may +reschedule the request (so that the handler is again invoked when the requested +service completes and the cycle continues.) or may stop the active scheduler, +returning control to the main program for termination.

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