org.jcsp.lang

Class AltingChannelInputSymmetricImpl<T>

java.lang.Object

org.jcsp.lang.Guard

org.jcsp.lang.AltingChannelInput<T>

org.jcsp.lang.AltingChannelInputSymmetricImpl<T>

All Implemented Interfaces:

ChannelInput<T>, MultiwaySynchronisation, Poisonable

class AltingChannelInputSymmetricImpl<T>
extends AltingChannelInput<T>
implements MultiwaySynchronisation

Field Summary

Fields

Modifier and Type	Field and Description
private AltingBarrier	ab
private ChannelInput<T>	in
private boolean	syncDone

Constructor Summary

Constructors

Constructor and Description
AltingChannelInputSymmetricImpl(AltingBarrier ab, ChannelInput<T> in)

Method Summary

Modifier and Type	Method and Description
(package private) boolean	disable() Disables the guard for selection.
(package private) boolean	enable(Alternative alt) Returns true if the event is ready.
void	endRead() End an extended rendezvous.
boolean	pending() Returns whether there is data pending on this channel.
void	poison(int strength) This injects poison into the channel.
T	read() Read an Object from the channel.
T	startRead() Begin an extended rendezvous read from the channel.

Methods inherited from class org.jcsp.lang.Guard

schedule

Methods inherited from class java.lang.Object

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

Field Detail

ab

private final AltingBarrier ab

in

private final ChannelInput<T> in

syncDone

private boolean syncDone

Constructor Detail

AltingChannelInputSymmetricImpl

public AltingChannelInputSymmetricImpl(AltingBarrier ab,
                                       ChannelInput<T> in)

Method Detail

enable

boolean enable(Alternative alt)

Description copied from class: Guard

Returns true if the event is ready. Otherwise, this enables the guard for selection and returns false.

Note: this method should only be called by the Alternative class

Specified by:

enable in class Guard

Parameters:

alt - the Alternative class that is controlling the selection

Returns:

true if and only if the event is ready

disable

boolean disable()

Description copied from class: Guard

Disables the guard for selection. Returns true if the event was ready.

Note: this method should only be called by the Alternative class

Specified by:

disable in class Guard

Returns:

true if and only if the event was ready

read

public T read()

Description copied from interface: ChannelInput

Read an Object from the channel.

Specified by:

read in interface ChannelInput<T>

Returns:

the object read from the channel

pending

public boolean pending()

Description copied from class: AltingChannelInput

Returns whether there is data pending on this channel.

Note: if there is, it won't go away until you read it. But if there isn't, there may be some by the time you check the result of this method.

Specified by:

pending in class AltingChannelInput<T>

Returns:

state of the channel.

poison

public void poison(int strength)

Description copied from interface: Poisonable

This injects poison into the channel. If the channel was not explicitly constructed to be poisonable or if the strength of poison is not greater than the channel immunity level, the poison will have no effect.

Specified by:

poison in interface Poisonable

Parameters:

strength - the strength of the poison (must be >= 0).

endRead

public void endRead()

Description copied from interface: ChannelInput

End an extended rendezvous. It must be invoked once (and only once) following a startRead.

Specified by:

endRead in interface ChannelInput<T>

startRead

public T startRead()

Description copied from interface: ChannelInput

Begin an extended rendezvous read from the channel. An extended rendezvous is not completed until the reader has completed its extended action. This method starts an extended rendezvous. When a writer to this channel writes, this method returns what was sent immediately. The extended rendezvous continues with reader actions until the reader invokes endRead. Only then will the writer be released (from its write method). The writer is unaware of the extended nature of the communication.

The reader process must call endRead at some point after this function, otherwise the writer will not be freed and deadlock will probably follow.

The reader process may perform any actions between calling startRead and endRead, including communications on other channels. Further communications on this channel, of course, should not be made.

An extended rendezvous may be started after the channel's Guard has been selected by an Alternative (i.e. startRead instead of read).

Specified by:

startRead in interface ChannelInput<T>

Returns:

The object read from the channel