Class CBioAsyncWaiter

class CBioAsyncWaiter : public CActive;

Description

Utility class for waiting for asychronous requests.

This class allows asynchronous requests to be made from synchronous objects. This object is used by passing its iStatus to an asynchronous request and then calling Start(). The result of the request can be obtained by calling the Result() method.

Derivation

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

• CActive - The core class of the active object abstraction

• CBioAsyncWaiter - Utility class for waiting for asychronous requests

Members

Defined in CBioAsyncWaiter:
DoCancel(), NewLC(), Result(), RunL(), StartAndWait(), ~CBioAsyncWaiter()

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()

static IMPORT_C CBioAsyncWaiter *NewLC();

Description

Standard 2-phase contruction.

Allocates and initialises the object.

Return value

CBioAsyncWaiter * A pointer to the created object.

IMPORT_C ~CBioAsyncWaiter();

Description

Destructor.

Also cancels any outstanding requests.

IMPORT_C void StartAndWait();

Description

Starts the asynchronous request.

Starts the active scheduler and waits for the asynchronous request to complete.

IMPORT_C TInt Result() const;

Description

Obtains the result of the asynchronous request.

Returns the error code of the last asynchronous request that was made.

Return value

TInt KErrNone is request was successful, otherwise the error code that the request completed with.

private: virtual void RunL();

Description

Handles an active object's request completion event.

A derived class must provide an implementation to handle the completed request. If appropriate, it may issue another request.

The function is called by the active scheduler when a request completion event occurs, i.e. after the active scheduler's WaitForAnyRequest() function completes.

Before calling this active object's RunL() function, the active scheduler has:

1. decided that this is the highest priority active object with a completed request

2. marked this active object's request as complete (i.e. the request is no longer outstanding)

RunL() runs under a trap harness in the active scheduler. If it leaves, then the active scheduler calls RunError() to handle the leave.

Note that once the active scheduler's Start() function has been called, all user code is run under one of the program's active object's RunL() or RunError() functions.

private: virtual void DoCancel();

Description

Implements cancellation of an outstanding request.

This function is called as part of the active object's Cancel().

It must call the appropriate cancel function offered by the active object's asynchronous service provider. The asynchronous service provider's cancel is expected to act immediately.

DoCancel() must not wait for event completion; this is handled by Cancel().