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org.ematgine.utils.concurrent
Class SynchronizedDouble  

java.lang.Object
  org.ematgine.utils.concurrent.SynchronizedVariable
      org.ematgine.utils.concurrent.SynchronizedDouble

All Implemented Interfaces:

java.lang.Cloneable, java.lang.Comparable, Executor

Direct Known Subclasses:

WaitableDouble

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public class SynchronizedDouble

extends SynchronizedVariable

implements java.lang.Comparable, java.lang.Cloneable

A class useful for offloading synch for double instance variables.

[ Introduction to this package. ]

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Field Summary
protected  double	value_

 

Fields inherited from class org.ematgine.utils.concurrent.SynchronizedVariable

lock_

 

Constructor Summary

SynchronizedDouble(double initialValue)           Make a new SynchronizedDouble with the given initial value, and using its own internal lock.

SynchronizedDouble(double initialValue, java.lang.Object lock)           Make a new SynchronizedDouble with the given initial value, and using the supplied lock.

 

Method Summary
double	add(double amount)           Add amount to value (i.e., set value += amount)
boolean	commit(double assumedValue, double newValue)           Set value to newValue only if it is currently assumedValue.
int	compareTo(double other)
int	compareTo(java.lang.Object other)           Compares this object with another, and returns a numerical result based on the comparison.
int	compareTo(SynchronizedDouble other)
double	divide(double factor)           Divide value by factor (i.e., set value /= factor)
boolean	equals(java.lang.Object other)           Determine whether this Object is semantically equal to another Object.
double	get()           Return the current value
int	hashCode()           Get a value that represents this Object, as uniquely as possible within the confines of an int.
double	multiply(double factor)           Multiply value by factor (i.e., set value *= factor)
double	set(double newValue)           Set to newValue.
double	subtract(double amount)           Subtract amount from value (i.e., set value -= amount)
double	swap(SynchronizedDouble other)           Atomically swap values with another SynchronizedDouble.
java.lang.String	toString()           Convert this Object to a human-readable String.

 

Methods inherited from class org.ematgine.utils.concurrent.SynchronizedVariable

execute, getLock

 

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

 

Field Detail

value_

protected double value_

Constructor Detail

SynchronizedDouble

public SynchronizedDouble(double initialValue)

Make a new SynchronizedDouble with the given initial value, and using its own internal lock.

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SynchronizedDouble

public SynchronizedDouble(double initialValue,
                          java.lang.Object lock)

Make a new SynchronizedDouble with the given initial value, and using the supplied lock.

Method Detail

get

public final double get()

Return the current value

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set

public double set(double newValue)

Set to newValue.

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commit

public boolean commit(double assumedValue,
                      double newValue)

Set value to newValue only if it is currently assumedValue.

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swap

public double swap(SynchronizedDouble other)

Atomically swap values with another SynchronizedDouble. Uses identityHashCode to avoid deadlock when two SynchronizedDoubles attempt to simultaneously swap with each other. (Note: Ordering via identyHashCode is not strictly guaranteed by the language specification to return unique, orderable values, but in practice JVMs rely on them being unique.)

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add

public double add(double amount)

Add amount to value (i.e., set value += amount)

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subtract

public double subtract(double amount)

Subtract amount from value (i.e., set value -= amount)

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multiply

public double multiply(double factor)

Multiply value by factor (i.e., set value *= factor)

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divide

public double divide(double factor)

Divide value by factor (i.e., set value /= factor)

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compareTo

public int compareTo(double other)

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compareTo

public int compareTo(SynchronizedDouble other)

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compareTo

public int compareTo(java.lang.Object other)

Description copied from interface: java.lang.Comparable

Compares this object with another, and returns a numerical result based on the comparison. If the result is negative, this object sorts less than the other; if 0, the two are equal, and if positive, this object sorts greater than the other. To translate this into boolean, simply perform o1.compareTo(o2) <op> 0, where op is one of <, <=, =, !=, >, or >=.

You must make sure that the comparison is mutual, ie. sgn(x.compareTo(y)) == -sgn(y.compareTo(x)) (where sgn() is defined as -1, 0, or 1 based on the sign). This includes throwing an exception in either direction if the two are not comparable; hence, compareTo(null) should always throw an Exception.

You should also ensure transitivity, in two forms: x.compareTo(y) > 0 && y.compareTo(z) > 0 implies x.compareTo(z) > 0; and x.compareTo(y) == 0 implies x.compareTo(z) == y.compareTo(z).

Specified by:

compareTo in interface java.lang.Comparable

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equals

public boolean equals(java.lang.Object other)

Description copied from class: java.lang.Object

Determine whether this Object is semantically equal to another Object.

There are some fairly strict requirements on this method which subclasses must follow:

• It must be transitive. If a.equals(b) and b.equals(c), then a.equals(c) must be true as well.
• It must be symmetric. a.equals(b) and b.equals(a) must have the same value.
• It must be reflexive. a.equals(a) must always be true.
• It must be consistent. Whichever value a.equals(b) returns on the first invocation must be the value returned on all later invocations.
• a.equals(null) must be false.
• It must be consistent with hashCode(). That is, a.equals(b) must imply a.hashCode() == b.hashCode(). The reverse is not true; two objects that are not equal may have the same hashcode, but that has the potential to harm hashing performance.

This is typically overridden to throw a java.lang.ClassCastException if the argument is not comparable to the class performing the comparison, but that is not a requirement. It is legal for a.equals(b) to be true even though a.getClass() != b.getClass(). Also, it is typical to never cause a java.lang.NullPointerException.

In general, the Collections API (java.util) use the equals method rather than the == operator to compare objects. However, java.util.IdentityHashMap is an exception to this rule, for its own good reasons.

The default implementation returns this == o.

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hashCode

public int hashCode()

Description copied from class: java.lang.Object

Get a value that represents this Object, as uniquely as possible within the confines of an int.

There are some requirements on this method which subclasses must follow:

• Semantic equality implies identical hashcodes. In other words, if a.equals(b) is true, then a.hashCode() == b.hashCode() must be as well. However, the reverse is not necessarily true, and two objects may have the same hashcode without being equal.
• It must be consistent. Whichever value o.hashCode() returns on the first invocation must be the value returned on all later invocations as long as the object exists. Notice, however, that the result of hashCode may change between separate executions of a Virtual Machine, because it is not invoked on the same object.

Notice that since hashCode is used in java.util.Hashtable and other hashing classes, a poor implementation will degrade the performance of hashing (so don't blindly implement it as returning a constant!). Also, if calculating the hash is time-consuming, a class may consider caching the results.

The default implementation returns System.identityHashCode(this)

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toString

public java.lang.String toString()

Description copied from class: java.lang.Object

Convert this Object to a human-readable String. There are no limits placed on how long this String should be or what it should contain. We suggest you make it as intuitive as possible to be able to place it into System.out.println() 55 and such.

It is typical, but not required, to ensure that this method never completes abruptly with a java.lang.RuntimeException.

This method will be called when performing string concatenation with this object. If the result is null, string concatenation will instead use "null".

The default implementation returns getClass().getName() + "@" + Integer.toHexString(hashCode()).

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