An active object that performs processing that is only performed once. More...
#include <e32base.h>
Public Member Functions | |
| IMPORT_C | CAsyncOneShot (TInt aPriority) |
| Constructor taking a priority value. | |
| virtual IMPORT_C void | DoCancel () |
| Implements cancellation of an outstanding request. | |
| virtual IMPORT_C void | Call () |
| Queues this active object to be run once. | |
| virtual IMPORT_C | ~CAsyncOneShot () |
| Frees resources prior to destruction. | |
| RThread & | Thread () |
| Gets a handle to the current thread. | |
 Public Member Functions inherited from CActive | |
| IMPORT_C | ~CActive () |
| Frees resources prior to destruction. | |
| IMPORT_C void | Cancel () |
| Cancels the wait for completion of an outstanding request. | |
| IMPORT_C void | Deque () |
| Removes the active object from the active scheduler's list of active objects. | |
| IMPORT_C void | SetPriority (TInt aPriority) |
| Sets the priority of the active object. | |
| TBool | IsActive () const |
| Determines whether the active object has a request outstanding. | |
| TBool | IsAdded () const |
| Determines whether the active object has been added to the active scheduler's list of active objects. | |
| TInt | Priority () const |
| Gets the priority of the active object. | |
| Public Member Functions inherited from CBase | |
| CBase () | |
| Default constructor. | |
| virtual IMPORT_C | ~CBase () |
| Virtual destructor. | |
| TAny * | operator new (TUint aSize, TAny *aBase) __NO_THROW |
| Initialises the object to binary zeroes. | |
| TAny * | operator new (TUint aSize) __NO_THROW |
| Allocates the object from the heap and then initialises its contents to binary zeroes. | |
| TAny * | operator new (TUint aSize, TLeave) |
| Allocates the object from the heap and then initialises its contents to binary zeroes. | |
| TAny * | operator new (TUint aSize, TUint aExtraSize) __NO_THROW |
| Allocates the object from the heap and then initialises its contents to binary zeroes. | |
| TAny * | operator new (TUint aSize, TLeave, TUint aExtraSize) |
| Allocates the object from the heap and then initialises its contents to binary zeroes. | |
Additional Inherited Members | |
| Public Types inherited from CActive | |
| enum | TPriority { EPriorityIdle =-100 , EPriorityLow =-20 , EPriorityStandard =0 , EPriorityUserInput =10 , EPriorityHigh =20 } |
| Defines standard priorities for active objects. More... | |
| Static Public Member Functions inherited from CBase | |
| static IMPORT_C void | Delete (CBase *aPtr) |
| Deletes the specified object. | |
| Public Attributes inherited from CActive | |
| TRequestStatus | iStatus |
| The request status associated with an asynchronous request. | |
| Protected Member Functions inherited from CActive | |
| IMPORT_C | CActive (TInt aPriority) |
| Constructs the active object with the specified priority. | |
| IMPORT_C void | SetActive () |
| Indicates that the active object has issued a request and that it is now outstanding. | |
| virtual void | RunL ()=0 |
| Handles an active object's request completion event. | |
| virtual IMPORT_C TInt | RunError (TInt aError) |
| Handles a leave occurring in the request completion event handler RunL(). | |
| virtual IMPORT_C TInt | Extension_ (TUint aExtensionId, TAny *&a0, TAny *a1) |
| Extension function. | |
Detailed Description
An active object that performs processing that is only performed once.
The active object is intended to be given a low priority, so that it runs only when no higher-priority active objects are ready to run. In addition, the class ensures that the current thread cannot be closed until the active object is destroyed.
The class needs to be derived from to make use of its behaviour, in particular, it needs to define and implement a RunL() function.
NB: the constructor creates a process-relative handle to the current thread and this is stored within this object. If the thread subsequently dies abnormally, then this handle will not be closed, and the thread will not be destroyed until the process terminates.
NB: if Call() is called from a different thread (for example, to implement a kind of inter-thread communication), a client-specific mechanism must be used to ensure that the thread that created this object is still alive.
NB: if the thread that created this object has its own heap and terminates abnormally, then the handle stored within this object is lost.
- See also
- CActive::RunL
- CAsyncOneShot::Call
- API status
- Published to all clients. Released API.
Constructor & Destructor Documentation
◆ CAsyncOneShot()
| IMPORT_C CAsyncOneShot::CAsyncOneShot | ( | TInt | aPriority | ) |
Constructor taking a priority value.
Specifically, the constructor:
- sets this active object's priority value
- opens a handle to the current thread to ensure that the thread cannot be closed until this CAsyncOneShot object is destroyed
- adds this active object to the current active scheduler.
- Parameters
-
aPriority The active object priority value. CActive::TPriority defines a standard set of priorities.
Panic condition: E32USER-CBase 93 if the attempt to open a handle to the current thread fails.
(generated from Symbian Developer Library)
◆ ~CAsyncOneShot()
|
virtual |
Frees resources prior to destruction.
Specifically, it closes the handle to the current thread.
(generated from Symbian Developer Library)
Member Function Documentation
◆ Call()
|
virtual |
Queues this active object to be run once.
Panic condition: E32USER-CBase 2 In debug builds only, if this active object has not already been added to the active scheduler.
(generated from Symbian Developer Library)
◆ DoCancel()
|
virtual |
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().
- See also
- CActive::Cancel
Implements CActive.
◆ Thread()
|
inline |
Gets a handle to the current thread.
(generated from Symbian Developer Library)
The documentation for this class was generated from the following files:
