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groovyx.gpars.dataflow
[Java] Class DataflowExpression

java.lang.Object
  groovyx.gpars.serial.WithSerialId
      groovyx.gpars.dataflow.DataflowExpression
All Implemented Interfaces:
groovy.lang.GroovyObject, DataflowReadChannel
@SuppressWarnings({"UnqualifiedStaticUsage", "CallToSimpleGetterFromWithinClass", "ConstantDeclaredInAbstractClass"})
public abstract class DataflowExpression
extends WithSerialId

The base class for all dataflow elements.

Authors:
Alex Tkachman, Vaclav Pech

Nested Class Summary
static class DataflowExpression.BindDataflow

Represents a remote message binding a value to a remoted DataflowExpression
class DataflowExpression.DataflowExpressionsCollector

Listener for availability of data flow expressions we depend from
private static class DataflowExpression.TransformMany

private static class DataflowExpression.TransformOne

private static class DataflowExpression.WaitingThread

A logical representation of a synchronous or asynchronous request to read the value once it is bound.
 
Field Summary
private static java.lang.String ATTACHMENT

private static java.lang.String RESULT

protected static int S_INITIALIZED

protected static int S_INITIALIZING

protected static int S_NOT_INITIALIZED

Possible states
private static DataflowExpression.WaitingThread dummyWaitingThread

A request chain terminator
private groovy.lang.MetaClass metaClass

The current metaclass
private static long serialVersionUID

protected int state

Holds the current state of the variable
protected static java.util.concurrent.atomic.AtomicIntegerFieldUpdater stateUpdater

Updater for the state field
protected T value

Holds the actual value.

private DataflowExpression.WaitingThread waiting

Points to the head of the chain of requests waiting for a value to be bound
protected static java.util.concurrent.atomic.AtomicReferenceFieldUpdater waitingUpdater

Updater for the waiting field
 
Fields inherited from class WithSerialId
serialHandle, serialVersionUID
 
Constructor Summary
DataflowExpression()

 
Method Summary
protected java.lang.Object DataflowExpression()

Creates a new unbound Dataflow Expression
void bind(T value)

Assigns a value to the variable.

void bindSafely(T value)

Assigns a value to the variable.

void bindUnique(T value)

Assigns a value to the variable.

private void doBind(T value)

Performs the actual bind operation, unblocks all blocked threads and informs all asynchronously waiting actors.
private void doBindImpl(T value)

void doBindRemote(java.util.UUID hostId, T message)

Binds the value after receiving a bing message over the wire
protected T evaluate()

Evaluate expression after the ones we depend on are ready
groovy.lang.MetaClass getMetaClass()

java.lang.Object getProperty(java.lang.String propertyName)

Returns either standard property of expression or creates expression, which will request given property when receiver became available
T getVal()

Reads the value of the variable.

T getVal(long timeout, java.util.concurrent.TimeUnit units)

Reads the value of the variable.

void getValAsync(MessageStream callback)

Asynchronously retrieves the value of the variable.

void getValAsync(java.lang.Object attachment, MessageStream callback)

Used by Dataflow operators.

private static void handleInterruption(java.util.concurrent.atomic.AtomicBoolean newWaiting)

java.lang.Object invokeMethod(java.lang.String name, java.lang.Object args)

boolean isBound()

Check if value has been set already for this expression
void join()

Blocks, if the value has not been assigned yet to the DataflowVariable
void join(long timeout, java.util.concurrent.TimeUnit units)

Blocks, if the value has not been assigned yet to the DataflowVariable
private void notifyRemote(java.util.UUID hostId)

Sends notifications to all subscribers
DataflowExpression poll()

Retrieves the bound value.

void rightShift(groovy.lang.Closure closure)

Schedule closure to be executed by pooled actor after data became available It is important to notice that even if data already available the execution of closure will not happen immediately but will be scheduled
private void scheduleCallback(java.lang.Object attachment, MessageStream callback)

Sends the result back to the actor, which is waiting asynchronously for the value to be bound.

void setMetaClass(groovy.lang.MetaClass metaClass)

void setProperty(java.lang.String propertyName, java.lang.Object newValue)

protected void subscribe()

Utility method to call at the very end of constructor of derived expressions.

protected void subscribe(DataflowExpression.DataflowExpressionsCollector listener)

java.lang.String toString()

static DataflowExpression transform(java.lang.Object another, groovy.lang.Closure closure)

void whenBound(groovy.lang.Closure closure)

Schedule closure to be executed by pooled actor after data becomes available It is important to notice that even if data already available the execution of closure will not happen immediately but will be scheduled.
void whenBound(Pool pool, groovy.lang.Closure closure)

Schedule closure to be executed by pooled actor after data becomes available It is important to notice that even if data already available the execution of closure will not happen immediately but will be scheduled.
void whenBound(PGroup group, groovy.lang.Closure closure)

Schedule closure to be executed by pooled actor after data becomes available It is important to notice that even if data already available the execution of closure will not happen immediately but will be scheduled.
void whenBound(MessageStream stream)

Send the bound data to provided stream when it becomes available
void wheneverBound(groovy.lang.Closure closure)

Send all pieces of data bound in the future to the provided stream when it becomes available *
void wheneverBound(MessageStream stream)

Send all pieces of data bound in the future to the provided stream when it becomes available
 
Methods inherited from class WithSerialId
createRemoteHandle, getOrCreateSerialHandle, getRemoteClass, writeReplace
 
Methods inherited from class java.lang.Object
java.lang.Object#wait(long), java.lang.Object#wait(), java.lang.Object#wait(long, int), java.lang.Object#equals(java.lang.Object), java.lang.Object#toString(), java.lang.Object#hashCode(), java.lang.Object#getClass(), java.lang.Object#notify(), java.lang.Object#notifyAll()
 

Field Detail

ATTACHMENT

private static final java.lang.String ATTACHMENT

RESULT

private static final java.lang.String RESULT

S_INITIALIZED

protected static final int S_INITIALIZED

S_INITIALIZING

protected static final int S_INITIALIZING

S_NOT_INITIALIZED

protected static final int S_NOT_INITIALIZED
Possible states

dummyWaitingThread

private static final DataflowExpression.WaitingThread dummyWaitingThread
A request chain terminator

metaClass

private groovy.lang.MetaClass metaClass
The current metaclass

serialVersionUID

private static final long serialVersionUID

state

protected int state
Holds the current state of the variable

stateUpdater

@SuppressWarnings({"rawtypes", "RawUseOfParameterizedType"})
protected static final java.util.concurrent.atomic.AtomicIntegerFieldUpdater stateUpdater
Updater for the state field

value

@SuppressWarnings({"InstanceVariableMayNotBeInitialized"})
protected T value
Holds the actual value. Is null before a concrete value is bound to it.

waiting

@SuppressWarnings({"UnusedDeclaration"})
    //modified through stateUpdater
private DataflowExpression.WaitingThread waiting
Points to the head of the chain of requests waiting for a value to be bound

waitingUpdater

@SuppressWarnings({"rawtypes", "RawUseOfParameterizedType"})
protected static final java.util.concurrent.atomic.AtomicReferenceFieldUpdater waitingUpdater
Updater for the waiting field

 
Constructor Detail

DataflowExpression

DataflowExpression()

 
Method Detail

DataflowExpression

protected java.lang.Object DataflowExpression()
Creates a new unbound Dataflow Expression

bind

public final void bind(T value)
Assigns a value to the variable. Can only be invoked once on each instance of DataflowVariable. Allows attempts to bind to equal values. Throws exception if invoked on an already bound variable.
Parameters:
value - The value to assign

bindSafely

public final void bindSafely(T value)
Assigns a value to the variable. Returns silently if invoked on an already bound variable.
Parameters:
value - The value to assign

bindUnique

public final void bindUnique(T value)
Assigns a value to the variable. Can only be invoked once on each instance of DataflowVariable Doesn't allow attempts to bind to equal values. Throws exception if invoked on an already bound variable.
Parameters:
value - The value to assign

doBind

private void doBind(T value)
Performs the actual bind operation, unblocks all blocked threads and informs all asynchronously waiting actors.
Parameters:
value - The value to assign

doBindImpl

private void doBindImpl(T value)

doBindRemote

public final void doBindRemote(java.util.UUID hostId, T message)
Binds the value after receiving a bing message over the wire
Parameters:
hostId - Id of the bind originator host
message - The value to bind

evaluate

protected T evaluate()
Evaluate expression after the ones we depend on are ready
Returns:
value to bind

getMetaClass

@Override
public final groovy.lang.MetaClass getMetaClass()

getProperty

@Override
public final java.lang.Object getProperty(java.lang.String propertyName)
Returns either standard property of expression or creates expression, which will request given property when receiver became available
Parameters:
propertyName - The name of the property to retrieve
Returns:
The property value, instance of DataflowGetPropertyExpression

getVal

@Override
public final T getVal()
Reads the value of the variable. Blocks, if the value has not been assigned yet.
throws:
InterruptedException If the current thread gets interrupted while waiting for the variable to be bound
Returns:
The actual value

getVal

@Override
public final T getVal(long timeout, java.util.concurrent.TimeUnit units)
Reads the value of the variable. Blocks up to given timeout, if the value has not been assigned yet.
throws:
InterruptedException If the current thread gets interrupted while waiting for the variable to be bound
Parameters:
timeout - The timeout value
units - Units for the timeout
Returns:
The actual value

getValAsync

@Override
public final void getValAsync(MessageStream callback)
Asynchronously retrieves the value of the variable. Sends the actual value of the variable as a message back the the supplied actor once the value has been bound. The actor can perform other activities or release a thread back to the pool by calling react() waiting for the message with the value of the Dataflow Variable.
Parameters:
callback - An actor to send the bound value to.

getValAsync

@Override
public final void getValAsync(java.lang.Object attachment, MessageStream callback)
Used by Dataflow operators. Asynchronously retrieves the value of the variable. Sends a message back the the supplied MessageStream with a map holding the supplied attachment under the 'attachment' key and the actual value of the variable under the 'result' key once the value has been bound. Attachment is an arbitrary value helping the actor.operator match its request with the reply. The actor/operator can perform other activities or release a thread back to the pool by calling react() waiting for the message with the value of the Dataflow Variable.
Parameters:
attachment - arbitrary non-null attachment if reader needs better identification of result
callback - An actor to send the bound value plus the supplied index to.

handleInterruption

private static void handleInterruption(java.util.concurrent.atomic.AtomicBoolean newWaiting)

invokeMethod

@Override
public final java.lang.Object invokeMethod(java.lang.String name, java.lang.Object args)

isBound

@Override
public final boolean isBound()
Check if value has been set already for this expression
Returns:
true if bound already

join

public final void join()
Blocks, if the value has not been assigned yet to the DataflowVariable
throws:
InterruptedException If the current thread gets interrupted while waiting for the variable to be bound

join

public final void join(long timeout, java.util.concurrent.TimeUnit units)
Blocks, if the value has not been assigned yet to the DataflowVariable
throws:
InterruptedException If the current thread gets interrupted while waiting for the variable to be bound
Parameters:
timeout - The timeout value
units - Units for the timeout

notifyRemote

private void notifyRemote(java.util.UUID hostId)
Sends notifications to all subscribers
Parameters:
hostId - The local host id

poll

@Override
public final DataflowExpression poll()
Retrieves the bound value. Returns null, if no value is available.
throws:
InterruptedException If the current thread is interrupted
Returns:
The value bound to the DFV or null

rightShift

@Override
public final void rightShift(groovy.lang.Closure closure)
Schedule closure to be executed by pooled actor after data became available It is important to notice that even if data already available the execution of closure will not happen immediately but will be scheduled
Parameters:
closure - closure to execute when data available

scheduleCallback

@SuppressWarnings({"TypeMayBeWeakened"})
private void scheduleCallback(java.lang.Object attachment, MessageStream callback)
Sends the result back to the actor, which is waiting asynchronously for the value to be bound. The message will either be a map holding the attachment under the 'attachment' key and the actual bound value under the 'result' key, or it will be the result itself if the callback doesn't care about the index.
Parameters:
attachment - An arbitrary object identifying the request
callback - The actor to send the message to

setMetaClass

@Override
public final void setMetaClass(groovy.lang.MetaClass metaClass)

setProperty

@Override
public final void setProperty(java.lang.String propertyName, java.lang.Object newValue)

subscribe

protected final void subscribe()
Utility method to call at the very end of constructor of derived expressions. Create and subscribe listener

subscribe

protected void subscribe(DataflowExpression.DataflowExpressionsCollector listener)

toString

@SuppressWarnings({"ArithmeticOnVolatileField"})
@Override
public java.lang.String toString()

transform

public static DataflowExpression transform(java.lang.Object another, groovy.lang.Closure closure)

whenBound

@Override
public final void whenBound(groovy.lang.Closure closure)
Schedule closure to be executed by pooled actor after data becomes available It is important to notice that even if data already available the execution of closure will not happen immediately but will be scheduled.
Parameters:
closure - closure to execute when data available

whenBound

@Override
public void whenBound(Pool pool, groovy.lang.Closure closure)
Schedule closure to be executed by pooled actor after data becomes available It is important to notice that even if data already available the execution of closure will not happen immediately but will be scheduled.
Parameters:
pool - The thread pool to use for task scheduling for asynchronous message delivery
closure - closure to execute when data available

whenBound

@Override
public final void whenBound(PGroup group, groovy.lang.Closure closure)
Schedule closure to be executed by pooled actor after data becomes available It is important to notice that even if data already available the execution of closure will not happen immediately but will be scheduled.
Parameters:
group - The PGroup to use for task scheduling for asynchronous message delivery
closure - closure to execute when data available

whenBound

@Override
public final void whenBound(MessageStream stream)
Send the bound data to provided stream when it becomes available
Parameters:
stream - stream where to send result

wheneverBound

@Override
public final void wheneverBound(groovy.lang.Closure closure)
Send all pieces of data bound in the future to the provided stream when it becomes available *
Parameters:
closure - closure to execute when data available

wheneverBound

@Override
public final void wheneverBound(MessageStream stream)
Send all pieces of data bound in the future to the provided stream when it becomes available
Parameters:
stream - stream where to send result

 

Copyright © 2008–2010 Václav Pech. All Rights Reserved.