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package com.c2kernel.entity.proxy;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.StringTokenizer;
import com.c2kernel.common.ObjectNotFoundException;
import com.c2kernel.entity.C2KLocalObject;
import com.c2kernel.utils.Logger;
public class MemberSubscription<C extends C2KLocalObject> implements Runnable {
public static final String ERROR = "Error";
public static final String END = "theEND";
ItemProxy subject;
String interest;
// keep the subscriber by weak reference, so it is not kept from the garbage collector if no longer used
WeakReference<ProxyObserver<C>> observerReference;
ArrayList<String> contents = new ArrayList<String>();
boolean preLoad;
public MemberSubscription(ProxyObserver<C> observer, String interest, boolean preLoad) {
setObserver(observer);
this.interest = interest;
this.preLoad = preLoad;
}
@Override
public void run() {
Thread.currentThread().setName("Member Subscription: "+subject.getPath()+":"+interest);
if (preLoad) loadChildren();
}
private void loadChildren() {
C newMember;
ProxyObserver<C> observer = getObserver();
if (observer == null) return; //reaped
try {
// fetch contents of path
String children = subject.queryData(interest+"/all");
StringTokenizer tok = new StringTokenizer(children, ",");
ArrayList<String> newContents = new ArrayList<String>();
while (tok.hasMoreTokens())
newContents.add(tok.nextToken());
// look to see what's new
for (String newChild: newContents) {
// load child object
try {
newMember = (C)subject.getObject(interest+"/"+newChild);
contents.remove(newChild);
observer.add(newMember);
} catch (ObjectNotFoundException ex) {
observer.control(ERROR, "Listed member "+newChild+" was not found.");
} catch (ClassCastException ex) {
Logger.error(ex);
observer.control(ERROR, "Listed member "+newChild+" was the wrong type.");
}
}
// report what's left in old contents as deleted
for (String oldChild: contents) {
observer.remove(interest+"/"+oldChild);
}
//replace contents arraylist
contents = newContents;
//report that we're done
observer.control(END, null);
} catch (Exception ex) {
observer.control(ERROR, "Query on "+interest+" failed with "+ex.getMessage());
}
}
public boolean isRelevant(String path) {
Logger.msg(7, "Checking relevance of "+path+" to "+interest);
return (path.startsWith(interest));
}
public void update(String path, boolean deleted) {
ProxyObserver<C> observer = getObserver();
if (observer == null) return; //reaped
Logger.msg(7, "Processing proxy message path "+path +" for "+observer+". Interest: "+interest+" Was Deleted:"+deleted);
if (!path.startsWith(interest)) // doesn't concern us
return;
if (path.equals(interest)) // refresh contents
loadChildren();
else {
String name = path.substring(interest.length());
if (deleted) {
Logger.msg(4, "Removing "+path);
contents.remove(name);
observer.remove(name);
}
else {
try {
C newMember = (C)subject.getObject(path);
Logger.msg(4, "Adding "+path);
contents.add(name);
observer.add(newMember);
} catch (ObjectNotFoundException e) {
Logger.error("Member Subscription: could not load "+path);
Logger.error(e);
}
}
}
}
public void setObserver(ProxyObserver<C> observer) {
observerReference = new WeakReference<ProxyObserver<C>>(observer);
}
public void setSubject(ItemProxy subject) {
this.subject = subject;
}
public ProxyObserver<C> getObserver() {
return observerReference.get();
}
}
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