groovyx.gpars.dataflow
Class DataflowVariable<T>

java.lang.Object
  groovyx.gpars.serial.WithSerialId
      groovyx.gpars.dataflow.DataflowExpression<T>
          groovyx.gpars.dataflow.DataflowVariable<T>

Type Parameters:

T - Type of values to bind with the DataflowVariable

All Implemented Interfaces:

groovy.lang.GroovyObject, DataflowChannel<T>, DataflowReadChannel<T>, DataflowWriteChannel<T>, Promise<T>, java.io.Serializable

Direct Known Subclasses:

DataflowVariable.RemoteDataflowVariable

public class DataflowVariable<T>
extends DataflowExpression<T>
implements DataflowChannel<T>, Promise<T>

Represents a thread-safe single-assignment, multi-read variable. Each instance of DataflowVariable can be read repeatedly any time using the 'val' property and assigned once in its lifetime using the '<<' operator. Reads preceding assignment will be blocked until the value is assigned. For actors and Dataflow Operators the asynchronous non-blocking variants of the getValAsync() methods can be used. They register the request to read a value and will send a message to the actor or operator once the value is available.

Author:

Vaclav Pech, Alex Tkachman Date: Jun 4, 2009

See Also:

Serialized Form

Nested Class Summary

static class

DataflowVariable.RemoteDataflowVariable<T>

Nested classes/interfaces inherited from class groovyx.gpars.dataflow.DataflowExpression

DataflowExpression.BindDataflow<T>, DataflowExpression.DataflowExpressionsCollector

Field Summary

private static long

serialVersionUID

Fields inherited from class groovyx.gpars.dataflow.DataflowExpression

S_INITIALIZED, S_INITIALIZING, S_NOT_INITIALIZED, state, stateUpdater, value, waitingUpdater

Fields inherited from class groovyx.gpars.serial.WithSerialId

serialHandle

Constructor Summary

DataflowVariable()
Creates a new unbound Dataflow Variable

Method Summary

private DataflowWriteChannel<T>	bindDFV(DataflowReadChannel<T> ref)
T	get() Retrieves the value of the variable, blocking until a value is available
T	get(long timeout, java.util.concurrent.TimeUnit units) Retrieves the value of the variable, blocking up to given timeout, if the value has not been assigned yet.
java.lang.Class<DataflowVariable.RemoteDataflowVariable>	getRemoteClass() Class of remote object to be created
DataflowWriteChannel<T>	leftShift(DataflowReadChannel<T> ref) Assigns a value from one DataflowVariable instance to this variable.
DataflowWriteChannel<T>	leftShift(T value) Assigns a value to the variable.

Methods inherited from class groovyx.gpars.dataflow.DataflowExpression

bind, bindSafely, bindUnique, doBindRemote, evaluate, getMetaClass, getProperty, getVal, getVal, getValAsync, getValAsync, invokeMethod, isBound, join, join, poll, rightShift, setMetaClass, setProperty, subscribe, subscribe, toString, transform, whenBound, whenBound, whenBound, whenBound, wheneverBound, wheneverBound

Methods inherited from class groovyx.gpars.serial.WithSerialId

createRemoteHandle, getOrCreateSerialHandle, writeReplace

Methods inherited from class java.lang.Object

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

Methods inherited from interface groovyx.gpars.dataflow.DataflowReadChannel

getVal, getVal, getValAsync, getValAsync, isBound, poll, rightShift, whenBound, whenBound, whenBound, whenBound, wheneverBound, wheneverBound

Methods inherited from interface groovyx.gpars.dataflow.DataflowWriteChannel

bind

Methods inherited from interface groovyx.gpars.dataflow.Promise

getVal, getVal, getValAsync, getValAsync, isBound, rightShift, whenBound, whenBound, whenBound, whenBound

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

Constructor Detail

DataflowVariable

public DataflowVariable()

Creates a new unbound Dataflow Variable

Method Detail

leftShift

public DataflowWriteChannel<T> leftShift(T value)

Assigns a value to the variable. Can only be invoked once on each instance of DataflowVariable

Specified by:

leftShift in interface DataflowWriteChannel<T>

Parameters:

value - The value to assign

Returns:

The current channel instance

leftShift

public DataflowWriteChannel<T> leftShift(DataflowReadChannel<T> ref)

Assigns a value from one DataflowVariable instance to this variable. Can only be invoked once on each instance of DataflowVariable

Specified by:

leftShift in interface DataflowWriteChannel<T>

Parameters:

ref - The DataflowVariable instance the value of which to bind

Returns:

The current channel instance

bindDFV

private DataflowWriteChannel<T> bindDFV(DataflowReadChannel<T> ref)

get

public T get()
      throws java.lang.Throwable

Retrieves the value of the variable, blocking until a value is available

Specified by:

get in interface Promise<T>

Returns:

The value stored in the variable

Throws:

java.lang.Throwable - If the stored value is an exception instance it gets re-thrown

get

public T get(long timeout,
             java.util.concurrent.TimeUnit units)
      throws java.lang.Throwable

Retrieves the value of the variable, blocking up to given timeout, if the value has not been assigned yet.

Specified by:

get in interface Promise<T>

Parameters:

timeout - The timeout value

units - Units for the timeout

Returns:

The value stored in the variable

Throws:

java.lang.Throwable - If the stored value is an exception instance it gets re-thrown

getRemoteClass

public java.lang.Class<DataflowVariable.RemoteDataflowVariable> getRemoteClass()

Description copied from class: WithSerialId

Class of remote object to be created

Overrides:

getRemoteClass in class WithSerialId

Returns:

Throws UnsupportedOperationException