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Location:
e32base.h
Link against: euser.lib
class CAsyncOneShot : public CActive;
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.
CBase
- Base class for all classes to be instantiated on the heap
CActive
- The core class of the active object abstraction
CAsyncOneShot
- An active object that performs processing that is only performed once
Defined in CAsyncOneShot
:
CAsyncOneShot()
, Call()
, DoCancel()
, Thread()
, ~CAsyncOneShot()
Inherited from CActive
:
Cancel()
,
Deque()
,
EPriorityHigh
,
EPriorityIdle
,
EPriorityLow
,
EPriorityStandard
,
EPriorityUserInput
,
Extension_()
,
IsActive()
,
IsAdded()
,
Priority()
,
RunError()
,
RunL()
,
SetActive()
,
SetPriority()
,
TPriority
,
iStatus
Inherited from CBase
:
Delete()
,
operator new()
IMPORT_C CAsyncOneShot(TInt aPriority);
Constructor taking a priority value.
Specifically, the constructor:
1. sets this active object's priority value
2. opens a handle to the current thread to ensure that the thread cannot be closed until this CAsyncOneShot object is destroyed
3. adds this active object to the current active scheduler.
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virtual IMPORT_C ~CAsyncOneShot();
Frees resources prior to destruction.
Specifically, it closes the handle to the current thread.
virtual IMPORT_C void DoCancel();
Implements cancellation of an outstanding request.
The class provides an empty implementation.
This is called by the destructor.
virtual IMPORT_C void Call();
Queues this active object to be run once.
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inline RThread &Thread();
Gets a handle to the current thread.
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