pt.ua.concurrent

Class Event

java.lang.Object

pt.ua.concurrent.CObject

pt.ua.concurrent.Event

All Implemented Interfaces:

InterruptibleAwaitingThreads, SyncCV

public class Event
extends CObject

A simple module supporting two valued events. An event is a double-valued variable (0 and 1), in which a client may wait for one of this two states.

This class follows DbC(tm) methodology (Wikipedia). Where possible, contracts are implement with native's Java assert.

Author:

Miguel Oliveira e Silva (mos@ua.pt)

Constructor Summary

Constructors

Constructor and Description
Event(boolean initial) Creates an event with initial state and registering waiting threads.
Event(boolean initial, boolean registerAwaitingThreads) Creates an event with initial state.

Method Summary

Modifier and Type	Method and Description
void	await(boolean state) Wait for a given state value.
void	reset() Reset the event state (false).
void	set() Set the event state (true).
boolean	stateMatches(boolean state) Does current state matches argument? This method should be used with utmost care, because its result, depending on the event's usage, might change immediately after it has been called (race condition).
void	toggle() Toggle the event state.

Methods inherited from class pt.ua.concurrent.CObject

await, await, await, broadcast, interruptWaitingThreads, lockIsMine, registerAwaitingThreads, signal, syncronizedLockIsMine

Methods inherited from class java.lang.Object

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

Constructor Detail

Event

public Event(boolean initial)

Creates an event with initial state and registering waiting threads.

Parameters:

initial - state value

Event

public Event(boolean initial,
             boolean registerAwaitingThreads)

Creates an event with initial state.

Parameters:

initial - the initial state

registerAwaitingThreads - if true, threads are registered when waiting

Method Detail

set

public void set()

Set the event state (true).

reset

public void reset()

Reset the event state (false).

toggle

public void toggle()

Toggle the event state.

stateMatches

public boolean stateMatches(boolean state)

Does current state matches argument? This method should be used with utmost care, because its result, depending on the event's usage, might change immediately after it has been called (race condition).

Parameters:

state - the state to test

Returns:

true, if state matches the argument, false otherwise

await

public void await(boolean state)
           throws ThreadInterruptedException

Wait for a given state value.

Parameters:

state - value to wait for

Throws:

ThreadInterruptedException