More progress on the distributed object stuff.
git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@19 542714f4-19e9-0310-aa3c-eee0fc999fb1
This commit is contained in:
Michael Bayne
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//
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// $Id: PresentsDObjectMgr.java,v 1.1 2001/06/01 19:56:13 mdb Exp $
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package com.threerings.cocktail.cher.server;
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import com.samskivert.util.Queue;
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import com.threerings.cocktail.cher.Log;
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import com.threerings.cocktail.cher.dobj.*;
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import com.threerings.cocktail.cher.util.IntMap;
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/**
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* The cher distributed object manager implements the
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* <code>DObjectManager</code> interface, providing an object manager that
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* runs on the server. By virtue of running on the server, it manages its
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* objects directly rather than managing proxies of objects which is what
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* is done on the client. Thus it simply queues up events and dispatches
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* them to subscribers.
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*
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* <p> The server object manager is meant to run on the main thread of the
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* server application and thus provides a method to be invoked by the
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* application main thread which won't return until the manager has been
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* requested to shut down.
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*/
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public class CherDObjectMgr implements DObjectManager
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{
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// inherit documentation from the interface
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public void createObject (Class dclass, Subscriber target,
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boolean subscribe)
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{
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// queue up a create object event
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postEvent(new CreateObjectEvent(dclass, target, subscribe));
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}
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// inherit documentation from the interface
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public void subscribeToObject (int oid, Subscriber target)
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{
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// queue up an access object event
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postEvent(new AccessObjectEvent(oid, target, true));
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}
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// inherit documentation from the interface
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public void fetchObject (int oid, Subscriber target)
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{
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// queue up an access object event
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postEvent(new AccessObjectEvent(oid, target, false));
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}
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// inherit documentation from the interface
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public void postEvent (DEvent event)
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{
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// just append it to the queue
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_evqueue.append(event);
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}
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/**
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* Initializes the dobjmgr and prepares it for operation.
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*/
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public void init ()
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{
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// we create a dummy object to live as oid zero and we'll use that
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// for some internal event trickery
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DObject dummy = new DObject();
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dummy.init(0, this);
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_objects.put(0, new DObject());
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}
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/**
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* Runs the dobjmgr event loop until it is requested to exit. This
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* should be called from the main application thread.
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*/
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public void run ()
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{
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Log.info("DOMGR running.");
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while (isRunning()) {
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// pop the next event off the queue
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DEvent event = (DEvent)_evqueue.get();
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// look up the target object
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DObject target = (DObject)_objects.get(event.getTargetOid());
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if (target == null) {
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Log.warning("Event target no longer exists " +
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"[event=" + event + "].");
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continue;
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}
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// check the event's permissions
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if (!target.checkPermissions(event)) {
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Log.warning("Event failed permissions check " +
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"[event=" + event + ", target=" + target + "].");
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continue;
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}
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try {
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// everything's good so far, apply the event to the object
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if (!event.applyToObject(target)) {
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// if the event returns false from applyToObject, this
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// means it's a silent event and we shouldn't notify
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// the subscribers
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continue;
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}
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} catch (Exception e) {
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Log.warning("Failure applying event [event=" + event +
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", target=" + target + ", error=" + e + "].");
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continue;
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}
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try {
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// and notify the object's subscribers
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target.notifySubscribers(event);
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} catch (Exception e) {
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Log.warning("Failure dispatching event [event=" + event +
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", target=" + target + "].");
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Log.logStackTrace(e);
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}
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}
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Log.info("DOMGR exited.");
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}
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/**
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* Requests that the dobjmgr shut itself down. It will exit the event
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* processing loop which cause <code>run()</code> to return.
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*/
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public void shutdown ()
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{
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_running = false;
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// stick a bogus object on the event queue to ensure that the mgr
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// wakes up and smells the coffee
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_evqueue.append(this);
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}
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protected synchronized boolean isRunning ()
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{
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return _running;
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}
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protected int getNextOid ()
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{
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// look for the next unused oid. in theory if we had two billion
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// objects, this would loop infinitely, but the world would have
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// come to an end long before we had two billion objects
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do {
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_nextOid = (_nextOid + 1) % Integer.MAX_VALUE;
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} while (_objects.contains(_nextOid));
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return _nextOid;
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}
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protected boolean _running = true;
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protected Queue _evqueue = new Queue();
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protected IntMap _objects = new IntMap();
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protected int _nextOid = 0;
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/**
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* Used to create a distributed object and register it with the
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* system.
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*/
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protected class CreateObjectEvent extends DEvent
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{
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public CreateObjectEvent (Class clazz, Subscriber target,
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boolean subscribe)
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{
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super(0); // target the fake object
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_class = clazz;
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_target = target;
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_subscribe = subscribe;
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}
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public boolean applyToObject (DObject target)
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throws ObjectAccessException
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{
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try {
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// create a new instance of this object
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DObject obj = (DObject)_class.newInstance();
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int oid = getNextOid();
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// initialize this object
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obj.init(oid, CherDObjectMgr.this);
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// insert it into the table
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_objects.put(oid, obj);
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if (_target != null) {
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// add the subscriber to this object's subscriber list
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// if they requested it
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if (_subscribe) {
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obj.addSubscriber(_target);
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}
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// let the target subscriber know that their object is
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// available
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_target.objectAvailable(obj);
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}
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} catch (Exception e) {
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Log.warning("Object creation failure " +
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"[class=" + _class.getName() +
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", error=" + e + "].");
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// let the subscriber know shit be fucked
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if (_target != null) {
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String errmsg = "Object instantiation failed: " + e;
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_target.requestFailed(new ObjectAccessException(errmsg));
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}
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}
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// and return false to ensure that this event is not
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// dispatched to the fake object's subscriber list (even
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// though it's empty)
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return false;
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}
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protected Class _class;
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protected Subscriber _target;
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protected boolean _subscribe;
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}
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/**
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* Used to make an object available to a subscriber (with or without
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* the associated subscription).
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*/
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protected class AccessObjectEvent extends DEvent
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{
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public AccessObjectEvent (int oid, Subscriber target,
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boolean subscribe)
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{
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super(0); // target the bogus object
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_oid = oid;
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_target = target;
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_subscribe = subscribe;
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}
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public boolean applyToObject (DObject target)
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throws ObjectAccessException
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{
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// look up the target object
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DObject obj = (DObject)_objects.get(_oid);
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// if it don't exist, let them know
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if (obj == null) {
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_target.requestFailed(new NoSuchObjectException(_oid));
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return false;
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}
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// check permissions
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if (!obj.checkPermissions(_target)) {
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String errmsg = "m.access_denied\t" + _oid;
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_target.requestFailed(new ObjectAccessException(errmsg));
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return false;
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}
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// if they wanted to subscribe, do so
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if (_subscribe) {
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obj.addSubscriber(_target);
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}
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// let them know that things are groovy
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_target.objectAvailable(obj);
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// return false to ensure that this event is not dispatched to
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// the fake object's subscriber list (even though it's empty)
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return false;
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}
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protected int _oid;
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protected Subscriber _target;
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protected boolean _subscribe;
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}
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}
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