Class CMsvOperationWait

class CMsvOperationWait : public CActive;

Description

Utility class used to wait until an asynchronous messaging operation has completed.

Note that CMsvOperationActiveSchedulerWait is simpler to use, and should be used in preference to this class.

To use the class:

1. Create a new CMsvOperationWait object

2. Call the messaging function that returns the asynchronous operation. The operation observer parameter should be the iStatus word of the CMsvOperationWait object. This means that the CMsvOperationWait object will be signalled when the operation completes.

3. Call the CMsvOperationWait object's CMsvOperationWait::Start() function. This sets the object to be active.

4. Call CActiveScheduler::Start(). This starts a nested active scheduler. The program will then wait until this active scheduler is stopped. The CMsvOperationWait object stops the scheduler when the operation completes, allowing the program to continue.

These steps cause the program to wait until the operation completes.

     CMsvOperationWait* waiter=CMsvOperationWait::NewLC();
     CMsvOperation* op = function_returning_opLC(waiter->iStatus);
     waiter->Start();
     CActiveScheduler::Start();
     CleanupStack::PopAndDestroy(2); // op, waiter

Derivation

• CBase - Base class for all classes to be instantiated on the heap.

• CActive - The core class of the active object abstraction.

• CMsvOperationWait - Utility class used to wait until an asynchronous messaging operation has complet...

Members

Defined in CMsvOperationWait:

• DoCancel()Implements cancellation of an outstanding request.
• NewLC(TInt)Allocates and constructs a new CMsvOperationWait object.
• RunL()Handles a request completion event.
• Start()Sets the object to be active.
• ~CMsvOperationWait()Destructor.

Inherited from CActive:

• CActive(TInt)Constructs the active object with the specified priority.
• Cancel()Cancels the wait for completion of an outstanding request.
• Deque()Removes the active object from the active scheduler's list of active objects.
• EPriorityHighA priority higher than EPriorityUserInput.
• EPriorityIdleA low priority, useful for active objects representing background processing.
• EPriorityLowA priority higher than EPriorityIdle but lower than EPriorityStandard.
• EPriorityStandardMost active objects will have this priority.
• EPriorityUserInputA priority higher than EPriorityStandard; useful for active objects handling use...
• Extension_(TUint,TAny *&,TAny *)Extension function
• IsActive()constDetermines whether the active object has a request outstanding.
• IsAdded()constDetermines whether the active object has been added to the active scheduler's li...
• Priority()constGets the priority of the active object.
• RunError(TInt)Handles a leave occurring in the request completion event handler CActive::RunL(...
• SetActive()Indicates that the active object has issued a request and that it is now outstan...
• SetPriority(TInt)Sets the priority of the active object.
• TPriorityDefines standard priorities for active objects.
• iStatusThe request status associated with an asynchronous request.

Inherited from CBase:

• Delete(CBase *)Deletes the specified object.
• operator new(TUint)Allocates the object from the heap and then initialises its contents to binary z...
• operator new(TUint,TAny *)Initialises the object to binary zeroes.
• operator new(TUint,TLeave)Allocates the object from the heap and then initialises its contents to binary z...
• operator new(TUint,TLeave,TUint)Allocates the object from the heap and then initialises its contents to binary z...
• operator new(TUint,TUint)Allocates the object from the heap and then initialises its contents to binary z...

See also:

• CActiveScheduler...

IMPORT_C static CMsvOperationWait* NewLC(TInt aPriority=EPriorityStandard);

Description

Allocates and constructs a new CMsvOperationWait object.

The new object is added to the active scheduler and left on the cleanup stack.

Parameters

TInt aPriority Active object priority. It has a default value of EPriorityStandard.

Return value

CMsvOperationWait * New CMsvOperationWait object

Leave codes

KErrNoMemory

IMPORT_C ~CMsvOperationWait();

Description

Destructor.

Any active request on the object is cancelled.

IMPORT_C void Start();

Description

Sets the object to be active.

protected: virtual void RunL();

Description

Handles a request completion event.

The function stops the current active scheduler.

See also:

• CActive::RunL()Handles an active object's request completion event.

protected: virtual void DoCancel();

Description

Implements cancellation of an outstanding request.

See also:

• CActive::DoCancel()Implements cancellation of an outstanding request.