de.intarsys.tools.resourcetracker.ResourceTracker Maven / Gradle / Ivy
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/*
* Copyright (c) 2007, intarsys consulting GmbH
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* - Neither the name of intarsys nor the names of its contributors may be used
* to endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
package de.intarsys.tools.resourcetracker;
import java.lang.ref.ReferenceQueue;
/**
* An object to keep track of platform resources that should be disposed upon
* garbage collection of some container object.
*
* To use this create a subclass implementing the dispose strategy and add new
* resources using "track".
*
* The resources will be disposed automatically after garbage collection of the
* container in a separate worker thread.
*/
abstract public class ResourceTracker {
private IResourceReference[] references;
private int next = 0;
final private ResourceFinalizer finalizer;
public ResourceTracker() {
this(500);
}
public ResourceTracker(int size) {
super();
this.references = new IResourceReference[size];
this.finalizer = ResourceFinalizer.get();
}
public ResourceTracker(ResourceFinalizer finalizer) {
this(finalizer, 500);
}
public ResourceTracker(ResourceFinalizer finalizer, int size) {
super();
this.references = new IResourceReference[size];
this.finalizer = finalizer;
}
protected synchronized IResourceReference add(IResourceReference ref) {
finalizer.ensureStarted();
if (next >= references.length) {
// ooops - maybe finalizer thread is starving. help!
System.gc();
finalizer.drainQueue();
if (next >= references.length) {
IResourceReference[] newReferences = new IResourceReference[references.length << 1];
System.arraycopy(references, 0, newReferences, 0,
references.length);
references = newReferences;
}
}
references[next++] = ref;
return ref;
}
abstract protected void basicDispose(Object resource);
protected void dispose(IResourceReference ref) {
remove(ref);
if (ref.getResource() != null) {
basicDispose(ref.getResource());
}
}
protected ReferenceQueue getQueue() {
return finalizer.getQueue();
}
synchronized protected void remove(IResourceReference ref) {
int length = next;
for (int i = 0; i < length; i++) {
if (references[i] == ref) {
next--;
references[i] = references[next];
references[next] = null;
break;
}
}
// System.out.println("tracker removed instance, now " + next);
}
public IResourceReference trackPhantom(Object container, Object resource) {
return add(new PhantomResourceReference(container, resource, this));
}
public IResourceReference trackSoft(Object container, Object resource) {
return add(new SoftResourceReference(container, resource, this));
}
public IResourceReference trackWeak(Object container, Object resource) {
return add(new WeakResourceReference(container, resource, this));
}
}