edu.rit.pj.reduction

Class SharedBoolean

java.lang.Object

edu.rit.pj.reduction.SharedBoolean

public class SharedBoolean
extends java.lang.Object

Class SharedBoolean provides a reduction variable for a value of type boolean.

Class SharedBoolean is multiple thread safe. The methods use lock-free atomic compare-and-set.

Note: Class SharedBoolean is implemented using class java.util.concurrent.atomic.AtomicBoolean. The Boolean value is stored as an int with 0 = false and 1 = true.

Constructor Summary

Constructors

Constructor and Description
SharedBoolean() Construct a new Boolean reduction variable with the initial value false.
SharedBoolean(boolean initialValue) Construct a new Boolean reduction variable with the given initial value.

Method Summary

Modifier and Type	Method and Description
boolean	compareAndSet(boolean expect, boolean update) Atomically set this reduction variable to the given updated value if the current value equals the expected value.
boolean	get() Returns this reduction variable's current value.
boolean	getAndSet(boolean value) Set this reduction variable to the given value and return the previous value.
boolean	reduce(boolean value, BooleanOp op) Combine this reduction variable with the given value using the given operation.
void	set(boolean value) Set this reduction variable to the given value.
java.lang.String	toString() Returns a string version of this reduction variable.
boolean	weakCompareAndSet(boolean expect, boolean update) Atomically set this reduction variable to the given updated value if the current value equals the expected value.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

SharedBoolean

public SharedBoolean()

Construct a new Boolean reduction variable with the initial value false.

SharedBoolean

public SharedBoolean(boolean initialValue)

Construct a new Boolean reduction variable with the given initial value.

Parameters:

initialValue - Initial value.

Method Detail

get

public boolean get()

Returns this reduction variable's current value.

Returns:

Current value.

set

public void set(boolean value)

Set this reduction variable to the given value.

Parameters:

value - New value.

getAndSet

public boolean getAndSet(boolean value)

Set this reduction variable to the given value and return the previous value.

Parameters:

value - New value.

Returns:

Previous value.

compareAndSet

public boolean compareAndSet(boolean expect,
                             boolean update)

Atomically set this reduction variable to the given updated value if the current value equals the expected value.

Parameters:

expect - Expected value.

update - Updated value.

Returns:

True if the update happened, false otherwise.

weakCompareAndSet

public boolean weakCompareAndSet(boolean expect,
                                 boolean update)

Atomically set this reduction variable to the given updated value if the current value equals the expected value. May fail spuriously.

Parameters:

expect - Expected value.

update - Updated value.

Returns:

True if the update happened, false otherwise.

reduce

public boolean reduce(boolean value,
                      BooleanOp op)

Combine this reduction variable with the given value using the given operation. The result is stored back into this reduction variable and is returned.

Parameters:

value - Value.

op - Binary operation.

Returns:

(This variable) op (value).

toString

public java.lang.String toString()

Returns a string version of this reduction variable.

Overrides:

toString in class java.lang.Object

Returns:

String version.