groovyx.gpars.dataflow.impl

Class SelectBase<T>

java.lang.Object

groovyx.gpars.dataflow.impl.SelectBase<T>

public final class SelectBase<T>
extends java.lang.Object

The implementation of the core for all selects.

Author:

Vaclav Pech Date: 29th Sep 2010

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.List<SelectableChannel<? extends T>>	channels
private boolean[]	disabledDFVs Since DataflowVariables should be only read once, they need to be disabled after selecting their value The array stores a boolean flag for each index, indicating, whether the channel/variable has been disabled
private int	numberOfChannels
private java.util.Collection<SelectRequest<T>>	pendingRequests Unsatisfied requests for value, each holding a list of guards and a routine to invoke once a value is available
private java.util.Random	position

Constructor Summary

Constructors

Constructor and Description
SelectBase(PGroup pGroup, java.util.List<SelectableChannel<? extends T>> channels) Stores the input channel and registers for the wheneverBound() event on each

Method Summary

Methods

Modifier and Type	Method and Description
(package private) void	boundNotification(int index, SelectableChannel<? extends T> channel) Invoked by the SelectCallback instances, potentially concurrently to inform about new values being available for read from channels.
private void	disableDFV(int currentPosition, SelectableChannel<? extends T> channel) Sets the flag in the disabledDFVs array, if the channel is a DFV
void	doSelect(int startIndex, SelectRequest<T> selectRequest) Invoked whenever the Select is asked for the next value.

Methods inherited from class java.lang.Object

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

Field Detail

channels

private final java.util.List<SelectableChannel<? extends T>> channels

numberOfChannels

private final int numberOfChannels

disabledDFVs

private final boolean[] disabledDFVs

Since DataflowVariables should be only read once, they need to be disabled after selecting their value The array stores a boolean flag for each index, indicating, whether the channel/variable has been disabled

pendingRequests

private final java.util.Collection<SelectRequest<T>> pendingRequests

Unsatisfied requests for value, each holding a list of guards and a routine to invoke once a value is available

position

private final java.util.Random position

Constructor Detail

SelectBase

public SelectBase(PGroup pGroup,
          java.util.List<SelectableChannel<? extends T>> channels)

Stores the input channel and registers for the wheneverBound() event on each

Parameters:

pGroup - The group, the thread pool of which should be used for notification message handlers

channels - All the input channels to select on

Method Detail

boundNotification

void boundNotification(int index,
                     SelectableChannel<? extends T> channel)
                 throws java.lang.InterruptedException

Invoked by the SelectCallback instances, potentially concurrently to inform about new values being available for read from channels.

Parameters:

index - The index of the ready channel

channel - The channel itself

Throws:

java.lang.InterruptedException - If the thread is interrupted during value retrieval from the channel

doSelect

public void doSelect(int startIndex,
            SelectRequest<T> selectRequest)
              throws java.lang.InterruptedException

Invoked whenever the Select is asked for the next value. Depending on the supplied startIndex value it scans all input channels and reads the first one found, which currently has a value available for read. If no input channel is ready, the supplied SelectRequest instance is registered to be notified by the wheneverBound() channel listeners.

Parameters:

startIndex - The index of the channel to check first for available messages, -1 if start at a random position. Continue scanning by increasing the index, once the size is reached start from 0.

selectRequest - The request that holds the guards and expects a notification once a value is selected

Throws:

java.lang.InterruptedException - If the thread gets interrupted while reading messages from the channels

disableDFV

private void disableDFV(int currentPosition,
              SelectableChannel<? extends T> channel)

Sets the flag in the disabledDFVs array, if the channel is a DFV

Parameters:

currentPosition - The position to mark

channel - The channel being considered