edu.rice.hj.runtime.eventcount

Class HjSeqEventCount

java.lang.Object

edu.rice.hj.runtime.eventcount.HjSeqEventCount

All Implemented Interfaces:

HjEventCount

public final class HjSeqEventCount
extends Object
implements HjEventCount

Author:

Shams Imam (shams@rice.edu)

Constructor Summary

Constructors

Constructor and Description
HjSeqEventCount(int initialCount)

Method Summary

Modifier and Type	Method and Description
void	advance() The primitive advance() is used to signal the occurrence of an event.
void	await(long v) Quite often, a process may not wish to execute until some event in a class in which it has interest has happened.
long	read() Return the current value of an eventcount.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HjSeqEventCount

public HjSeqEventCount(int initialCount)

Method Detail

advance

public void advance()

The primitive advance() is used to signal the occurrence of an event. The effect of this operation is to increase the integer value of the eventcount by 1.

Specified by:

advance in interface HjEventCount

read

public long read()

Return the current value of an eventcount. It equals the number of advance operations that have been performed on it. To be more precise, the value returned by read() counts all of the advance operations that precede the execution, and may or may not count those in progress during the read. Thus, although the value may be changing during the execution of the read primitive, the result of read() is a lower bound on the current value of E after the read, and an upper bound on the value of E before the read.

Specified by:

read in interface HjEventCount

Returns:

the current value of an eventcount.

await

public void await(long v)
           throws SuspendableException

Quite often, a process may not wish to execute until some event in a class in which it has interest has happened. Although that effect can be achieved by looping around an execution of a read() primitive until a specified value of the eventcount, E, is reached, it is more useful to provide a primitive that incorporates the waiting. Such a primitive would also provide the opportunity to avoid the busy form of waiting. Consequently, we define a primitive await(E, v) that suspends the calling process until the value of the eventcount E is at least v. Of course, as in all mechanisms designed for asynchronous processes, the await primitive may not return immediately once the vth advance on E is executed; the only guarantee is that at least v advances have been performed by the time await(E, v) returns.

Specified by:

await in interface HjEventCount

Parameters:

v - The value of the eventcount to wait until

Throws:

SuspendableException