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CDeltaTimer Class Reference

class CDeltaTimer : public CActive

A queue of timed events.

A timed event is a callback function encapsulated by a TDeltaTimerEntry object, and is intended to be called when the time interval represented by the event expires.

The queue itself is a TDeltaQue list. A timed event entry is added into a position in the queue that is determined by the time interval specified for that event. Although the time interval for a timed event is specified as an interval from the present moment, when added to the queue the implementation treats each event as having an interval from the previous timed event (or now).

CDeltaTimer is an active object, driven by an RTimer which is usually set to expire upon completion of the event at the head of the queue. If the time to the next event is too great or an event at the head of the queue has been removed, the timer may be set to expire prior to the event at the head of the queue (if any).

When the timer completes, the head of the queue is inspected to see whether the timed event at the head of the queue has expired. On expiry, the callback function represented by that timed event is called, and the timed event entry is removed from the queue. The queue then inspects further events for expiry, calling and removing them as necessary until either the queue is empty or there is an event in the future to wait for.

Note that the tick period is the minimum time interval for an event and the granularity of all timings using the queue. Note that in general, any event may be called back some time after it has expired and that specifically the duration of all events will at least be rounded up to a muliple of the tick period.

TDeltaTimerEntry TDeltaQue RTimer

Inherits from

CDeltaTimer
- CActive
  - CBase

Public Member Functions
	~CDeltaTimer ()
IMPORT_C CDeltaTimer *	NewL ( TInt )
IMPORT_C CDeltaTimer *	NewL ( TInt , TTimeIntervalMicroSeconds32 )
IMPORT_C void	Queue ( TTimeIntervalMicroSeconds32 , TDeltaTimerEntry &)
IMPORT_C TInt	QueueLong ( TTimeIntervalMicroSeconds , TDeltaTimerEntry &)
IMPORT_C void	Remove ( TDeltaTimerEntry &)

Private Member Functions
	CDeltaTimer ( TInt , TInt )
void	Activate ( TBool )
void	DoCancel ()
void	RunL ()

Inherited Functions
	CActive::CActive(TInt)
	CActive::Cancel()
	CActive::Deque()
	CActive::Extension_(TUint,TAny &,TAny )
	CActive::IsActive()const
	CActive::IsAdded()const
	CActive::Priority()const
	CActive::RunError(TInt)
	CActive::SetActive()
	CActive::SetPriority(TInt)
	CActive::~CActive()
	CBase::CBase()
	CBase::Delete(CBase *)
	CBase::operator new(TUint)
	CBase::operator new(TUint,TAny *)
	CBase::operator new(TUint,TLeave)
	CBase::operator new(TUint,TLeave,TUint)
	CBase::operator new(TUint,TUint)
	CBase::~CBase()

Inherited Enumerations
	CActive:TPriority

Private Attributes
TTickCountQue	iQueue
TBool	iQueueBusy
const TInt	iTickPeriod
RTimer	iTimer

Inherited Attributes
	CActive::iStatus

Constructor & Destructor Documentation

CDeltaTimer(TInt, TInt)

CDeltaTimer	(	TInt	aPriority,
		TInt	aTickPeriod
	)	[private]

Constructor taking an active object priority value.

The constructor sets this active object's priority value through a call to the base class constructor in its c'tor list.

Parameters

TInt aPriority	The priority of this active object.
TInt aTickPeriod	The period of a tick on the system.

~CDeltaTimer()

~CDeltaTimer

(

)

Destructor.

Frees all resources before destruction of the object. Specifically, it cancels any outstanding timer requests generated by the RTimer object and then deletes all timed event entries from the timed event queue.

RTimer

Member Functions Documentation

Activate(TBool)

void

Activate

(

TBool

aRequeueTimer = EFalse

)

[private]

Issues a new RTimer request, if there is no outstanding request and the queue is not empty.

Parameters

TBool aRequeueTimer = EFalse

DoCancel()

void

DoCancel

(

)

[private, virtual]

Implements cancellation of an oustanding RTimer request.

NewL(TInt)

IMPORT_C CDeltaTimer *

NewL

(

TInt

aPriority

)

[static]

Creates a new timed event queue with the specified active object priority.

Parameters

TInt aPriority

The priority of this active object.

NewL(TInt, TTimeIntervalMicroSeconds32)

IMPORT_C CDeltaTimer *	NewL	(	TInt	aPriority,
			TTimeIntervalMicroSeconds32	aGranularity
		)	[static]

Creates a new timed event queue with the specified active object priority, and the specified timer granularity.

Parameters

TInt aPriority	The priority of this active object.
TTimeIntervalMicroSeconds32 aGranularity	Ignored. The resolution of the timer is the tick period.

Queue(TTimeIntervalMicroSeconds32, TDeltaTimerEntry &)

IMPORT_C void	Queue	(	TTimeIntervalMicroSeconds32	aTimeInMicroSeconds,
			TDeltaTimerEntry &	aEntry
		)	[virtual]

Adds a new timed event entry into the timed event queue.

Parameters

TTimeIntervalMicroSeconds32 aTimeInMicroSeconds	The interval from the present time when the timed event entry is to expire.
TDeltaTimerEntry & aEntry	The timed event entry encapsulating the call back that is to be called when this timed event entry expires.

QueueLong(TTimeIntervalMicroSeconds, TDeltaTimerEntry &)

IMPORT_C TInt	QueueLong	(	TTimeIntervalMicroSeconds	aTimeInMicroSeconds,
			TDeltaTimerEntry &	aEntry
		)

Adds a new timed event entry into the timed event queue.

Parameters

TTimeIntervalMicroSeconds aTimeInMicroSeconds	The interval from the present time when the timed event entry is to expire.
TDeltaTimerEntry & aEntry	The timed event entry encapsulating the call back that is to be called when this timed event entry expires.

Remove(TDeltaTimerEntry &)

IMPORT_C void

Remove

(

TDeltaTimerEntry &

aEntry

)

[virtual]

Removes the specified timed event entry from the timer queue.

Parameters

TDeltaTimerEntry & aEntry

The timed event entry.

RunL()

void

RunL

(

)

[private, virtual]

Deals with an RTimer completion event.

The function inspects the timed event entry at the head of the queue, and reduces its timer value by the appropriate amount. If this timed event is now found to have expired, the call back function is called, and the timed event entry removed from the queue.

If the timed event entry has not expired, it remains at the head of the queue.

The function issues a new RTimer request, using the timer granularity value as the time interval.

RTimer CActive