More progress on the distributed object stuff.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@19 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/presents/dobj/AttributeChangedEvent.java

@@ -1,8 +1,11 @@
 //
-// $Id: AttributeChangedEvent.java,v 1.1 2001/06/01 07:12:13 mdb Exp $
+// $Id: AttributeChangedEvent.java,v 1.2 2001/06/01 19:56:13 mdb Exp $
 
 package com.threerings.cocktail.cher.dobj;
 
+import java.lang.reflect.Method;
+import com.threerings.cocktail.cher.Log;
+
 /**
  * An attribute changed event is dispatched when a single attribute of a
  * distributed object has changed. It can also be constructed to request
@@ -92,6 +95,24 @@ public class AttributeChangedEvent extends DEvent
         return ((Double)_value).doubleValue();
     }
 
+    /**
+     * Applies this attribute change to the object.
+     */
+    public boolean applyToObject (DObject target)
+        throws ObjectAccessException
+    {
+        // look up the setter for this object
+        Method setter = DEventUtil.getSetter(target.getClass(), _name);
+
+        try {
+            setter.invoke(target, new Object[] { _value });
+        } catch (Exception e) {
+            throw new ObjectAccessException("Reflection error: " + e);
+        }
+
+        return true;
+    }
+
     protected String _name;
     protected Object _value;
 }

src/java/com/threerings/presents/dobj/DEvent.java

@@ -1,5 +1,5 @@
 //
-// $Id: DEvent.java,v 1.2 2001/06/01 07:12:13 mdb Exp $
+// $Id: DEvent.java,v 1.3 2001/06/01 19:56:13 mdb Exp $
 
 package com.threerings.cocktail.cher.dobj;
 
@@ -9,7 +9,7 @@ package com.threerings.cocktail.cher.dobj;
  * notification purposes, without making any modifications to the object
  * that defines the delivery group (the object's subscribers).
  */
-public class DEvent
+public abstract class DEvent
 {
     /**
      * Returns the oid of the object that is the target of this event.
@@ -19,6 +19,22 @@ public class DEvent
         return _toid;
     }
 
+    /**
+     * Applies the attribute modifications represented by this event to
+     * the specified target object. This is called by the distributed
+     * object manager in the course of dispatching events and should not
+     * be called directly.
+     *
+     * @exception ObjectAccessException thrown if there is any problem
+     * applying the event to the object (invalid attribute, etc.).
+     *
+     * @return true if the object manager should go on to notify the
+     * object's subscribers of this event, false if the event should be
+     * treated silently and the subscribers should not be notified.
+     */
+    public abstract boolean applyToObject (DObject target)
+        throws ObjectAccessException;
+
     /**
      * Constructs a new distributed object event that pertains to the
      * specified distributed object.

src/java/com/threerings/presents/dobj/DEventUtil.java

@@ -0,0 +1,66 @@
+//
+// $Id: DEventUtil.java,v 1.1 2001/06/01 19:56:13 mdb Exp $
+
+package com.threerings.cocktail.cher.dobj;
+
+import java.lang.reflect.Method;
+import java.util.HashMap;
+
+/**
+ * A repository for distributed object event related utility functions.
+ */
+public class DEventUtil
+{
+    /**
+     * Looks up and returns the method used to set an attribute of the
+     * specified name on an instance of the specified distributed object
+     * class.
+     */
+    public static Method getSetter (Class clazz, String name)
+        throws ObjectAccessException
+    {
+        // first see if it's cached
+        Method setter = (Method)_setterCache.get(name);
+        if (setter != null) {
+            return setter;
+        }
+
+        // convert the attribute name into a setter name
+        String sname = setterName(name);
+        try {
+            // look up that method (we don't have the parameter types, so
+            // we have to do our own name matching)
+            Method[] methods = clazz.getMethods();
+            for (int i = 0; i < methods.length; i++) {
+                if (methods[i].getName().equals(sname)) {
+                    setter = methods[i];
+                    break;
+                }
+            }
+
+        } catch (SecurityException se) {
+            throw new ObjectAccessException("Reflection error: " + se);
+        }
+
+        // make sure we found a matching method
+        if (setter == null) {
+            String errmsg = "No setter for attribute '" + name + "'.";
+            throw new ObjectAccessException(errmsg);
+        }
+
+        // and cache it
+        _setterCache.put(name, setter);
+        return setter;
+    }
+
+    protected static String setterName (String name)
+    {
+        StringBuffer sname = new StringBuffer();
+        sname.append("get");
+        sname.append(Character.toUpperCase(name.charAt(0)));
+        sname.append(name.substring(1));
+        return sname.toString();
+    }
+
+    protected static HashMap _setterCache = new HashMap();
+}

src/java/com/threerings/presents/dobj/DObject.java

@@ -1,5 +1,5 @@
 //
-// $Id: DObject.java,v 1.6 2001/06/01 05:17:16 mdb Exp $
+// $Id: DObject.java,v 1.7 2001/06/01 19:56:13 mdb Exp $
 
 package com.threerings.cocktail.cher.dobj;
 
@@ -73,17 +73,17 @@ import java.util.ArrayList;
 public class DObject
 {
     /**
-     * Constructs a new distributed object with the supplied object id.
-     * This should not be called directly, rather objects should be
-     * created via the distributed object manager.
+     * Initializes this distributed object with the supplied object id and
+     * distributed object manager. This is called by the distributed
+     * object manager when an object is created and registered with the
+     * system. Don't call this function yourself.
      *
      * @see DObjectManager.createObject
      */
-    public DObject (int oid, DObjectManager manager)
+    public void init (int oid, DObjectManager mgr)
     {
         _oid = oid;
-        _mgr = manager;
-        _subscribers = new ArrayList();
+        _mgr = mgr;
     }
 
     /**
@@ -106,10 +106,10 @@ public class DObject
      * <p> If the specified subscriber is already subscribed to this
      * object, they will not be added to the list a second time.
      */
-    public void addSubscriber (Subscriber subscriber)
+    public void addSubscriber (Subscriber sub)
     {
-        if (!_subscribers.contains(subscriber)) {
-            _subscribers.add(subscriber);
+        if (!_subscribers.contains(sub)) {
+            _subscribers.add(sub);
         }
     }
 
@@ -121,12 +121,66 @@ public class DObject
      * subscriber is not currently on the list of subscribers for this
      * object, nothing happens.
      */
-    public void removeSubscriber (Subscriber subscriber)
+    public void removeSubscriber (Subscriber sub)
     {
-        _subscribers.remove(subscriber);
+        _subscribers.remove(sub);
+    }
+
+    /**
+     * Checks to ensure that the specified subscriber has access to this
+     * object. This will be called before satisfying any fetch or
+     * subscription request. By default objects are accessible to all
+     * subscriber, but certain objects may wish to implement more fine
+     * grained access control.
+     *
+     * @param sub the subscriber that will fetch or subscribe to this
+     * object.
+     *
+     * @return true if the subscriber has access to the object, false if
+     * they do not.
+     */
+    public boolean checkPermissions (Subscriber sub)
+    {
+        return true;
+    }
+
+    /**
+     * Checks to ensure that this event which is about to be processed,
+     * has the appropriate permissions. By default objects accept all
+     * manner of events, but certain objects may wish to implement more
+     * fine grained access control.
+     *
+     * @param event the event that will be dispatched, object permitting.
+     *
+     * @return true if the event is valid and should be dispatched, false
+     * if the event fails the permissions check and should be aborted.
+     */
+    public boolean checkPermissions (DEvent event)
+    {
+        return true;
+    }
+
+    /**
+     * Called by the distributed object manager after it has applied an
+     * event to this object. This dispatches an event notification to all
+     * of the subscribers of this object.
+     *
+     * @param event the event that was just applied.
+     */
+    public void notifySubscribers (DEvent event)
+    {
+        for (int i = 0; i < _subscribers.size(); i++) {
+            Subscriber sub = (Subscriber)_subscribers.get(i);
+            // notify the subscriber
+            if (!sub.handleEvent(event, this)) {
+                // if they return false, we need to remove them from the
+                // subscriber list
+                _subscribers.remove(i--);
+            }
+        }
     }
 
     protected int _oid;
     protected DObjectManager _mgr;
-    protected ArrayList _subscribers;
+    protected ArrayList _subscribers = new ArrayList();
 }

src/java/com/threerings/presents/server/PresentsDObjectMgr.java

@@ -0,0 +1,272 @@
+//
+// $Id: PresentsDObjectMgr.java,v 1.1 2001/06/01 19:56:13 mdb Exp $
+
+package com.threerings.cocktail.cher.server;
+
+import com.samskivert.util.Queue;
+
+import com.threerings.cocktail.cher.Log;
+import com.threerings.cocktail.cher.dobj.*;
+import com.threerings.cocktail.cher.util.IntMap;
+
+/**
+ * The cher distributed object manager implements the
+ * <code>DObjectManager</code> interface, providing an object manager that
+ * runs on the server. By virtue of running on the server, it manages its
+ * objects directly rather than managing proxies of objects which is what
+ * is done on the client. Thus it simply queues up events and dispatches
+ * them to subscribers.
+ *
+ * <p> The server object manager is meant to run on the main thread of the
+ * server application and thus provides a method to be invoked by the
+ * application main thread which won't return until the manager has been
+ * requested to shut down.
+ */
+public class CherDObjectMgr implements DObjectManager
+{
+    // inherit documentation from the interface
+    public void createObject (Class dclass, Subscriber target,
+                              boolean subscribe)
+    {
+        // queue up a create object event
+        postEvent(new CreateObjectEvent(dclass, target, subscribe));
+    }
+
+    // inherit documentation from the interface
+    public void subscribeToObject (int oid, Subscriber target)
+    {
+        // queue up an access object event
+        postEvent(new AccessObjectEvent(oid, target, true));
+    }
+
+    // inherit documentation from the interface
+    public void fetchObject (int oid, Subscriber target)
+    {
+        // queue up an access object event
+        postEvent(new AccessObjectEvent(oid, target, false));
+    }
+
+    // inherit documentation from the interface
+    public void postEvent (DEvent event)
+    {
+        // just append it to the queue
+        _evqueue.append(event);
+    }
+
+    /**
+     * Initializes the dobjmgr and prepares it for operation.
+     */
+    public void init ()
+    {
+        // we create a dummy object to live as oid zero and we'll use that
+        // for some internal event trickery
+        DObject dummy = new DObject();
+        dummy.init(0, this);
+        _objects.put(0, new DObject());
+    }
+
+    /**
+     * Runs the dobjmgr event loop until it is requested to exit. This
+     * should be called from the main application thread.
+     */
+    public void run ()
+    {
+        Log.info("DOMGR running.");
+
+        while (isRunning()) {
+            // pop the next event off the queue
+            DEvent event = (DEvent)_evqueue.get();
+
+            // look up the target object
+            DObject target = (DObject)_objects.get(event.getTargetOid());
+            if (target == null) {
+                Log.warning("Event target no longer exists " +
+                            "[event=" + event + "].");
+                continue;
+            }
+
+            // check the event's permissions
+            if (!target.checkPermissions(event)) {
+                Log.warning("Event failed permissions check " +
+                            "[event=" + event + ", target=" + target + "].");
+                continue;
+            }
+
+            try {
+                // everything's good so far, apply the event to the object
+                if (!event.applyToObject(target)) {
+                    // if the event returns false from applyToObject, this
+                    // means it's a silent event and we shouldn't notify
+                    // the subscribers
+                    continue;
+                }
+
+            } catch (Exception e) {
+                Log.warning("Failure applying event [event=" + event +
+                            ", target=" + target + ", error=" + e + "].");
+                continue;
+            }
+
+            try {
+                // and notify the object's subscribers
+                target.notifySubscribers(event);
+
+            } catch (Exception e) {
+                Log.warning("Failure dispatching event [event=" + event +
+                            ", target=" + target + "].");
+                Log.logStackTrace(e);
+            }
+        }
+
+        Log.info("DOMGR exited.");
+    }
+
+    /**
+     * Requests that the dobjmgr shut itself down. It will exit the event
+     * processing loop which cause <code>run()</code> to return.
+     */
+    public void shutdown ()
+    {
+        _running = false;
+        // stick a bogus object on the event queue to ensure that the mgr
+        // wakes up and smells the coffee
+        _evqueue.append(this);
+    }
+
+    protected synchronized boolean isRunning ()
+    {
+        return _running;
+    }
+
+    protected int getNextOid ()
+    {
+        // look for the next unused oid. in theory if we had two billion
+        // objects, this would loop infinitely, but the world would have
+        // come to an end long before we had two billion objects
+        do {
+            _nextOid = (_nextOid + 1) % Integer.MAX_VALUE;
+        } while (_objects.contains(_nextOid));
+
+        return _nextOid;
+    }
+
+    protected boolean _running = true;
+    protected Queue _evqueue = new Queue();
+    protected IntMap _objects = new IntMap();
+    protected int _nextOid = 0;
+
+    /**
+     * Used to create a distributed object and register it with the
+     * system.
+     */
+    protected class CreateObjectEvent extends DEvent
+    {
+        public CreateObjectEvent (Class clazz, Subscriber target,
+                                  boolean subscribe)
+        {
+            super(0); // target the fake object
+            _class = clazz;
+            _target = target;
+            _subscribe = subscribe;
+        }
+
+        public boolean applyToObject (DObject target)
+            throws ObjectAccessException
+        {
+            try {
+                // create a new instance of this object
+                DObject obj = (DObject)_class.newInstance();
+                int oid = getNextOid();
+
+                // initialize this object
+                obj.init(oid, CherDObjectMgr.this);
+                // insert it into the table
+                _objects.put(oid, obj);
+
+                if (_target != null) {
+                    // add the subscriber to this object's subscriber list
+                    // if they requested it
+                    if (_subscribe) {
+                        obj.addSubscriber(_target);
+                    }
+
+                    // let the target subscriber know that their object is
+                    // available
+                    _target.objectAvailable(obj);
+                }
+
+            } catch (Exception e) {
+                Log.warning("Object creation failure " +
+                            "[class=" + _class.getName() +
+                            ", error=" + e + "].");
+
+                // let the subscriber know shit be fucked
+                if (_target != null) {
+                    String errmsg = "Object instantiation failed: " + e;
+                    _target.requestFailed(new ObjectAccessException(errmsg));
+                }
+            }
+
+            // and return false to ensure that this event is not
+            // dispatched to the fake object's subscriber list (even
+            // though it's empty)
+            return false;
+        }
+
+        protected Class _class;
+        protected Subscriber _target;
+        protected boolean _subscribe;
+    }
+
+    /**
+     * Used to make an object available to a subscriber (with or without
+     * the associated subscription).
+     */
+    protected class AccessObjectEvent extends DEvent
+    {
+        public AccessObjectEvent (int oid, Subscriber target,
+                                  boolean subscribe)
+        {
+            super(0); // target the bogus object
+            _oid = oid;
+            _target = target;
+            _subscribe = subscribe;
+        }
+
+        public boolean applyToObject (DObject target)
+            throws ObjectAccessException
+        {
+            // look up the target object
+            DObject obj = (DObject)_objects.get(_oid);
+
+            // if it don't exist, let them know
+            if (obj == null) {
+                _target.requestFailed(new NoSuchObjectException(_oid));
+                return false;
+            }
+
+            // check permissions
+            if (!obj.checkPermissions(_target)) {
+                String errmsg = "m.access_denied\t" + _oid;
+                _target.requestFailed(new ObjectAccessException(errmsg));
+                return false;
+            }
+
+            // if they wanted to subscribe, do so
+            if (_subscribe) {
+                obj.addSubscriber(_target);
+            }
+
+            // let them know that things are groovy
+            _target.objectAvailable(obj);
+
+            // return false to ensure that this event is not dispatched to
+            // the fake object's subscriber list (even though it's empty)
+            return false;
+        }
+
+        protected int _oid;
+        protected Subscriber _target;
+        protected boolean _subscribe;
+    }
+}

src/java/com/threerings/presents/util/IntMap.java

@@ -0,0 +1,221 @@
+//
+// $Id: IntMap.java,v 1.1 2001/06/01 19:56:13 mdb Exp $
+
+package com.threerings.cocktail.cher.util;
+
+import java.util.Enumeration;
+import java.util.NoSuchElementException;
+
+/**
+ * An int map is like a hash map, but with ints as keys. We avoid the
+ * annoyance of having to create <code>Integer</code> objects every time
+ * we want to lookup or insert values. Like <code>java.util.HashMap</code>
+ * it is not thread safe.
+ */
+public class IntMap
+{
+    public final static int DEFAULT_BUCKETS = 64;
+
+    public IntMap (int buckets)
+    {
+	_buckets = new Record[buckets];
+    }
+
+    public IntMap ()
+    {
+	this(DEFAULT_BUCKETS);
+    }
+
+    public int size ()
+    {
+	return _size;
+    }
+
+    public void put (int key, Object value)
+    {
+	int index = Math.abs(key)%_buckets.length;
+	Record rec = _buckets[index];
+
+	// either we start a new chain
+	if (rec == null) {
+	    _buckets[index] = new Record(key, value);
+	    _size++; // we're bigger
+	    return;
+	}
+
+	// or we replace an element in an existing chain
+	Record prev = rec;
+	for (; rec != null; rec = rec.next) {
+	    if (rec.key == key) {
+		rec.value = value; // we're not bigger
+		return;
+	    }
+	    prev = rec;
+	}
+
+	// or we append it to this chain
+	prev.next = new Record(key, value);
+	_size++; // we're bigger
+    }
+
+    public Object get (int key)
+    {
+	int index = Math.abs(key)%_buckets.length;
+	for (Record rec = _buckets[index]; rec != null; rec = rec.next) {
+	    if (rec.key == key) {
+		return rec.value;
+	    }
+	}
+	return null;
+    }
+
+    public boolean contains (int key)
+    {
+	return get(key) != null;
+    }
+
+    public Object remove (int key)
+    {
+	int index = Math.abs(key)%_buckets.length;
+	Record rec = _buckets[index];
+
+	// if there's no chain, there's no object
+	if (rec == null) {
+	    return null;
+	}
+
+	// maybe it's the first one in this chain
+	if (rec.key == key) {
+	    _buckets[index] = rec.next;
+	    _size--;
+	    return rec.value;
+	}
+
+	// or maybe it's an element further down the chain
+	for (Record prev = rec; rec != null; rec = rec.next) {
+	    if (rec.key == key) {
+		prev.next = rec.next;
+		_size--;
+		return rec.value;
+	    }
+	    prev = rec;
+	}
+
+	return null;
+    }
+
+    public void clear ()
+    {
+	// abandon all of our hash chains (the joy of garbage collection)
+	for (int i = 0; i < _buckets.length; i++) {
+	    _buckets[i] = null;
+	}
+	// zero out our size
+	_size = 0;
+    }
+
+    public Enumeration keys ()
+    {
+	return new Enumerator(_buckets, true);
+    }
+
+    public Enumeration elements ()
+    {
+	return new Enumerator(_buckets, false);
+    }
+
+    protected static class Record
+    {
+	public Record next;
+	public int key;
+	public Object value;
+
+	public Record (int key, Object value)
+	{
+	    this.key = key;
+	    this.value = value;
+	}
+    }
+
+    class Enumerator implements Enumeration
+    {
+	public Enumerator (Record[] buckets, boolean returnKeys)
+	{
+	    _buckets = buckets;
+	    _index = buckets.length;
+	    _returnKeys = returnKeys;
+	}
+
+	public boolean hasMoreElements ()
+	{
+	    // if we're pointing to an entry, we've got more entries
+	    if (_record != null) {
+		return true;
+	    }
+
+	    // search backward through the buckets looking for the next
+	    // non-empty hash chain
+	    while (_index-- > 0) {
+		if ((_record = _buckets[_index]) != null) {
+		    return true;
+		}
+	    }
+
+	    // found no non-empty hash chains, we're done
+	    return false;
+	}
+
+	public Object nextElement ()
+	{
+	    // if we're not pointing to an entry, search for the next
+	    // non-empty hash chain
+	    if (_record == null) {
+		while ((_index-- > 0) &&
+		       ((_record = _buckets[_index]) == null));
+	    }
+
+	    // if we found a record, return it's value and move our record
+	    // reference to it's successor
+	    if (_record != null) {
+		Record r = _record;
+		_record = r.next;
+		return _returnKeys ? new Integer(r.key) : r.value;
+	    }
+
+	    throw new NoSuchElementException("IntMapEnumerator");
+	}
+
+	private int _index;
+	private Record _record;
+	private Record[] _buckets;
+	private boolean _returnKeys;
+    }
+
+//     public static void main (String[] args)
+//     {
+//         IntMap table = new IntMap();
+
+//         System.out.print("Inserting: ");
+//         for (int i = 10; i < 100; i++) {
+//             Integer value = new Integer(i);
+//             table.put(i, value);
+//             System.out.print("(" + i + "," + value + ")");
+//         }
+//         System.out.println("");
+
+//         System.out.print("Looking up: ");
+//         for (int i = 10; i < 100; i++) {
+//             System.out.print("(" + i + "," + table.get(i) + ")");
+//         }
+//         System.out.println("");
+
+//         System.out.print("Removing: ");
+//         for (int i = 10; i < 100; i++) {
+//             System.out.print("(" + i + "," + table.remove(i) + ")");
+//         }
+//         System.out.println("");
+//     }
+
+    private Record[] _buckets;
+    private int _size;
+}