Arc::IntraProcessCounter Class Reference

A class for counters used by threads within a single process. More...

#include <IntraProcessCounter.h>

Inheritance diagram for Arc::IntraProcessCounter:

Public Member Functions
	IntraProcessCounter (int limit, int excess)
virtual	~IntraProcessCounter ()
virtual int	getLimit ()
virtual int	setLimit (int newLimit)
virtual int	changeLimit (int amount)
virtual int	getExcess ()
virtual int	setExcess (int newExcess)
virtual int	changeExcess (int amount)
virtual int	getValue ()
virtual CounterTicket	reserve (int amount=1, Glib::TimeVal duration=ETERNAL, bool prioritized=false, Glib::TimeVal timeOut=ETERNAL)
Protected Member Functions
virtual void	cancel (IDType reservationID)
virtual void	extend (IDType &reservationID, Glib::TimeVal &expiryTime, Glib::TimeVal duration=ETERNAL)

Detailed Description

A class for counters used by threads within a single process.

This is a class for shared among different threads within a single process. See the Counter class for further information about counters and examples of usage.

Constructor & Destructor Documentation

Arc::IntraProcessCounter::IntraProcessCounter	(	int	limit,
		int	excess
	)

Creates an IntraProcessCounter with specified limit and excess.

This constructor creates a counter with the specified limit (amount of resources available for reservation) and excess limit (an extra amount of resources that may be used for prioritized reservations).

Parameters:

	limit	The limit of the counter.
	excess	The excess limit of the counter.

virtual Arc::IntraProcessCounter::~IntraProcessCounter ( ) [virtual]

Destructor.

This is the destructor of the IntraProcessCounter class. Does not need to do anything.

Member Function Documentation

virtual void Arc::IntraProcessCounter::cancel ( IDType reservationID ) [protected, virtual]

Cancellation of a reservation.

This method cancels a reservation. It is called by the CounterTicket that corresponds to the reservation.

Parameters:

reservationID

The identity number (key) of the reservation to cancel.

Implements Arc::Counter.

virtual int Arc::IntraProcessCounter::changeExcess ( int amount ) [virtual]

Changes the excess limit of the counter.

Changes the excess limit of the counter by adding a certain amount to the current excess limit.

Parameters:

amount

The amount by which to change the excess limit.

Returns:: The new excess limit.

Implements Arc::Counter.

virtual int Arc::IntraProcessCounter::changeLimit ( int amount ) [virtual]

Changes the limit of the counter.

Changes the limit of the counter by adding a certain amount to the current limit.

Parameters:

amount

The amount by which to change the limit.

Returns:: The new limit.

Implements Arc::Counter.

virtual void Arc::IntraProcessCounter::extend	(	IDType &	reservationID,
		Glib::TimeVal &	expiryTime,
		Glib::TimeVal	duration = `ETERNAL`
	)			`[protected, virtual]`

Extension of a reservation.

This method extends a reservation. It is called by the CounterTicket that corresponds to the reservation.

Parameters:

	reservationID	Used for input as well as output. Contains the identification number of the original reservation on entry and the new identification number of the extended reservation on exit.
	expiryTime	Used for input as well as output. Contains the expiry time of the original reservation on entry and the new expiry time of the extended reservation on exit.
	duration	The time by which to extend the reservation. The new expiration time is computed based on the current time, NOT the previous expiration time.

Implements Arc::Counter.

virtual int Arc::IntraProcessCounter::getExcess ( ) [virtual]

Returns the excess limit of the counter.

Returns the excess limit of the counter, i.e. by how much the usual limit may be exceeded by prioritized reservations.

Returns:: The excess limit.

Implements Arc::Counter.

virtual int Arc::IntraProcessCounter::getLimit ( ) [virtual]

Returns the current limit of the counter.

This method returns the current limit of the counter, i.e. how many units can be reserved simultaneously by different threads without claiming high priority.

Returns:: The current limit of the counter.

Implements Arc::Counter.

virtual int Arc::IntraProcessCounter::getValue ( ) [virtual]

Returns the current value of the counter.

Returns the current value of the counter, i.e. the number of unreserved units. Initially, the value is equal to the limit of the counter. When a reservation is made, the the value is decreased. Normally, the value should never be negative, but this may happen if there are prioritized reservations. It can also happen if the limit is decreased after some reservations have been made, since reservations are never revoked.

Returns:: The current value of the counter.

Implements Arc::Counter.

virtual CounterTicket Arc::IntraProcessCounter::reserve	(	int	amount = `1`,
		Glib::TimeVal	duration = `ETERNAL`,
		bool	prioritized = `false`,
		Glib::TimeVal	timeOut = `ETERNAL`
	)			`[virtual]`

Makes a reservation from the counter.

This method makes a reservation from the counter. If the current value of the counter is too low to allow for the reservation, the method blocks until the reservation is possible or times out.

Parameters:

	amount	The amount to reserve, default value is 1.
	duration	The duration of a self expiring reservation, default is that it lasts forever.
	prioritized	Whether this reservation is prioritized and thus allowed to use the excess limit.
	timeOut	The maximum time to block if the value of the counter is too low, default is to allow "eternal" blocking.