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 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 completed

Members

Defined in CMsvOperationWait:
DoCancel(), NewLC(), RunL(), Start(), ~CMsvOperationWait()

Inherited from CActive:
Cancel(), Deque(), EPriorityHigh, EPriorityIdle, EPriorityLow, EPriorityStandard, EPriorityUserInput, Extension_(), IsActive(), IsAdded(), Priority(), RunError(), SetActive(), SetPriority(), TPriority, iStatus

Inherited from CBase:
Delete(), operator new()

See also:

• CActiveScheduler

static IMPORT_C 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()

protected: virtual void DoCancel();

Description

Implements cancellation of an outstanding request.

See also:

• CActive::DoCancel()