org.jcsp.lang

Class RejectableAltingChannelInputImpl

java.lang.Object

org.jcsp.lang.Guard

org.jcsp.lang.AltingChannelInput

org.jcsp.lang.RejectableAltingChannelInput

org.jcsp.lang.RejectableAltingChannelInputImpl

All Implemented Interfaces:

ChannelInput, Poisonable, RejectableChannelInput

class RejectableAltingChannelInputImpl
extends RejectableAltingChannelInput

Field Summary

Fields

Modifier and Type	Field and Description
private ChannelInternals	channel
private int	immunity

Constructor Summary

Constructors

Constructor and Description
RejectableAltingChannelInputImpl(ChannelInternals _channel, int _immunity)

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.
java.lang.Object	read() Read an Object from the channel.
void	reject() Reject any data pending instead of reading it.
java.lang.Object	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

channel

private ChannelInternals channel

immunity

private int immunity

Constructor Detail

RejectableAltingChannelInputImpl

RejectableAltingChannelInputImpl(ChannelInternals _channel,
                                 int _immunity)

Method Detail

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

Returns:

state of the channel.

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

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

endRead

public void endRead()

Description copied from interface: ChannelInput

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

read

public java.lang.Object read()

Description copied from interface: ChannelInput

Read an Object from the channel.

Returns:

the object read from the channel

startRead

public java.lang.Object 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).

Returns:

The object read from 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.

Parameters:

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

reject

public void reject()

Description copied from class: RejectableAltingChannelInput

Reject any data pending instead of reading it. The currently blocked writer will receive a ChannelDataRejectedException.

Specified by:

reject in interface RejectableChannelInput

Specified by:

reject in class RejectableAltingChannelInput