Package VASSAL.tools.opcache

Class AbstractOpImpl<V>

java.lang.Object

VASSAL.tools.opcache.AbstractOpImpl<V>

All Implemented Interfaces:

Op<V>

Direct Known Subclasses:

AbstractOpImpl

public abstract class AbstractOpImpl<V>
extends Object
implements Op<V>

An abstract representation of an operation. AbstractOpImpl is the base class for all such operations. The results of all operations are memoized (using a memory-sensitive cache), so retrieving results is both fast and memory-efficient.

Warning: For efficiency reasons, the methods get() and get(OpObserver) do not return defensively, nor do the Futures returned by getFuture(OpObserver). That is, the object returned is possibly the one retained internally by the AbstractOpImpl. Therefore, objects obtained from an AbstractOpImpl must not be altered, as this might interfere with caching. If an object obtained this way needs to be modified, copy the object first and alter the copy.

Since:

3.1.0

Author:

Joel Uckelman

Field Summary

Fields

Modifier and Type	Field	Description
protected OpCache	cache	The cache which contains calculated results.

Constructor Summary

Constructors

Constructor	Description
AbstractOpImpl(OpCache cache)

Method Summary

Modifier and Type	Method	Description
abstract V	eval()	Runs the Op.
V	get()	V
get(OpObserver<V> obs)	Future<V>	getFuture(OpObserver<V> obs)
abstract List<Op<?>>	getSources()	Returns a list of Ops on which this Op depends.
OpCache.Key<V>	newKey()	Returns the current cache key for this Op.
void	update()	Invalidates the current cache key for this Op.

Methods inherited from class java.lang.Object

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

Field Details

cache

protected final OpCache cache

The cache which contains calculated results.

Constructor Details

AbstractOpImpl

public AbstractOpImpl(OpCache cache)

Parameters:

cache - the cache for storing our result

Method Details

getSources

public abstract List<Op<?>> getSources()

Returns a list of Ops on which this Op depends.

Specified by:

getSources in interface Op<V>

Returns:

the Ops on which this Op depends

eval

public abstract V eval()
                throws Exception

Runs the Op. This method should be called only by the caching framework.

Specified by:

eval in interface Op<V>

Returns:

the result of running this Op

Throws:

Exception

get

public V get()

get

public V get(OpObserver<V> obs)
      throws CancellationException,
InterruptedException,
ExecutionException

Throws:

CancellationException - if the operation was cancelled

InterruptedException - if the operation was interrupted

ExecutionException - if the operation failed

getFuture

public Future<V> getFuture(OpObserver<V> obs)
                    throws ExecutionException

Throws:

CancellationException - if the operation was cancelled

InterruptedException - if the operation was interrupted

ExecutionException - if the operation failed

newKey

public OpCache.Key<V> newKey()

Returns the current cache key for this Op.

Specified by:

newKey in interface Op<V>

Returns:

the current cache key for this Op

update

public void update()

Invalidates the current cache key for this Op.

Specified by:

update in interface Op<V>