edu.rice.hj.runtime.baseruntime

Class DataDrivenControl<ValueType>

java.lang.Object

edu.rice.hj.runtime.baseruntime.DataDrivenControl<ValueType>

Type Parameters:

ValueType - The type of the wrapped value

public final class DataDrivenControl<ValueType>
extends Object

A DataDrivenControl (DDC) is a wrapper over a value. The DDC also stores a list of @see Resumable instances suspended on the value. When the value becomes available those instances are resumed.

Author:

Shams Imam (shams@rice.edu)

Constructor Summary

Constructors

Constructor and Description
DataDrivenControl() No-args Constructor.
DataDrivenControl(boolean penalizeDuplicatePuts) Constructor for DataDrivenControl.

Method Summary

Modifier and Type	Method and Description
void	addResumable(Runnable resumable) Attach Runnable instances to the DDC.
ValueType	getValue() Returns the value associated with the DDC.
static void	pauseOnDdc(DataDrivenControl<?> ddc) Utility method to enable blocking busy-wait on a DataDrivenControl.
static void	pauseOnDdc(DataDrivenControl<?> ddc, int busyWaitLimit) Utility method to enable blocking busy-wait on a DataDrivenControl.
static void	pauseOnDdc(DataDrivenControl<?> ddc, int busyWaitLimit, Runnable preUnblockCallback) pauseOnDdc.
static void	pauseOnDdc(DataDrivenControl<?> ddc, Runnable preUnblockCallback) Utility method to enable blocking busy-wait on a DataDrivenControl.
boolean	setValue(ValueType theValue) Associated a new value with the DDC and resumes any suspended Runnable instances.
String	toString()
boolean	valueAvailable() This method is not synchronized.

Methods inherited from class java.lang.Object

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

Constructor Detail

DataDrivenControl

public DataDrivenControl()

No-args Constructor.

DataDrivenControl

public DataDrivenControl(boolean penalizeDuplicatePuts)

Constructor for DataDrivenControl.

Parameters:

penalizeDuplicatePuts - whether to report errors for duplicate puts.

Method Detail

pauseOnDdc

public static void pauseOnDdc(DataDrivenControl<?> ddc)
                       throws SuspendableException

Utility method to enable blocking busy-wait on a DataDrivenControl.

Delegates to pauseOnDdc(DataDrivenControl, int, Runnable) with the following call: pauseOnDdc(ddc, 1, null)

Parameters:

ddc - The DataDrivenControl to wait on.

Throws:

SuspendableException

pauseOnDdc

public static void pauseOnDdc(DataDrivenControl<?> ddc,
                              int busyWaitLimit,
                              Runnable preUnblockCallback)
                       throws SuspendableException

pauseOnDdc.

Parameters:

ddc - a DataDrivenControl object.

busyWaitLimit - The number of iterations to attempt to check the DDC before resorting to more expensive blocking thread calls

preUnblockCallback - a Runnable object.

Throws:

SuspendableException

valueAvailable

public boolean valueAvailable()

This method is not synchronized. As such it may return false even when a value has been set. It is expected the user code will handle this scenario. Since the user would end up attaching a Resumable to the DDC when the value is unavailable, synchronization issues are deferred to those methods.

Returns:

whether a value has been set on the DDC

addResumable

public void addResumable(Runnable resumable)

Attach Runnable instances to the DDC. When a value becomes available on the DDC all attached Runnables are resumed. Runnables are resumed immediately if a value is already available.

Parameters:

resumable - The Runnable instance to attach

pauseOnDdc

public static void pauseOnDdc(DataDrivenControl<?> ddc,
                              int busyWaitLimit)
                       throws SuspendableException

Utility method to enable blocking busy-wait on a DataDrivenControl.

Delegates to pauseOnDdc(DataDrivenControl, int, Runnable) with the following call: pauseOnDdc(ddc, busyWaitLimit, null)

Parameters:

ddc - The DataDrivenControl to wait on.

busyWaitLimit - The number of iterations to attempt to check the DDC before resorting to more expensive blocking thread calls

Throws:

SuspendableException

pauseOnDdc

public static void pauseOnDdc(DataDrivenControl<?> ddc,
                              Runnable preUnblockCallback)
                       throws SuspendableException

Utility method to enable blocking busy-wait on a DataDrivenControl.

Delegates to pauseOnDdc(DataDrivenControl, int, Runnable) with the following call: pauseOnDdc(ddc, 1, preUnblockCallback)

Parameters:

ddc - The DataDrivenControl to wait on.

preUnblockCallback - a Runnable object.

Throws:

SuspendableException

setValue

public boolean setValue(ValueType theValue)
                 throws IllegalStateException

Associated a new value with the DDC and resumes any suspended Runnable instances.

Parameters:

theValue - the value to associate with the DDC

Returns:

true if succeeded in associating theValue with the DDC, false otherwise

Throws:

IllegalStateException - when a second setValue() is attempted

getValue

public ValueType getValue()

Returns the value associated with the DDC. It will return the default null value when invoked before a value has been set on the DDC

Returns:

the value currently associated with the DDC

toString

public String toString()

Overrides:

toString in class Object