Modified event helper mechanism to allow helpers to abort the event

dispatch. Added code to abort object added events that are trying to add a
non-existent object to an oid list. Wrote test driver for this and
duplicate object add request handling.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@196 542714f4-19e9-0310-aa3c-eee0fc999fb1

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

@@ -1,5 +1,5 @@
 //
-// $Id: PresentsDObjectMgr.java,v 1.12 2001/08/08 00:28:49 mdb Exp $
+// $Id: PresentsDObjectMgr.java,v 1.13 2001/08/08 21:56:47 mdb Exp $
 
 package com.threerings.cocktail.cher.server;
 
@@ -126,16 +126,22 @@ public class CherDObjectMgr implements DObjectManager
             }
 
             try {
-                // everything's good so far, apply the event to the object
-                boolean notify = event.applyToObject(target);
-
                 // do any internal management necessary based on this
                 // event
                 Method helper = (Method)_helpers.get(event.getClass());
                 if (helper != null) {
-                    helper.invoke(this, new Object[] { event, target });
+                    // invoke the helper method
+                    Object rv =
+                        helper.invoke(this, new Object[] { event, target });
+                    // if helper returns false, we abort event processing
+                    if (!((Boolean)rv).booleanValue()) {
+                        continue;
+                    }
                 }
 
+                // everything's good so far, apply the event to the object
+                boolean notify = event.applyToObject(target);
+
                 // if the event returns false from applyToObject, this
                 // means it's a silent event and we shouldn't notify the
                 // subscribers
@@ -169,8 +175,11 @@ public class CherDObjectMgr implements DObjectManager
     /**
      * Called as a helper for <code>ObjectDestroyedEvent</code> events. It
      * removes the object from the object table.
+     *
+     * @return true if the event should be dispatched, false if it should
+     * be aborted.
      */
-    public void objectDestroyed (DEvent event, DObject target)
+    public boolean objectDestroyed (DEvent event, DObject target)
     {
         int oid = target.getOid();
 
@@ -240,6 +249,8 @@ public class CherDObjectMgr implements DObjectManager
                             "[target=" + target + ", field=" + field + "].");
             }
         }
+
+        return true;
     }
 
     /**
@@ -278,12 +289,22 @@ public class CherDObjectMgr implements DObjectManager
     /**
      * Called as a helper for <code>ObjectAddedEvent</code> events. It
      * updates the object/oid list tracking structures.
+     *
+     * @return true if the event should be dispatched, false if it should
+     * be aborted.
      */
-    public void objectAdded (DEvent event, DObject target)
+    public boolean objectAdded (DEvent event, DObject target)
     {
         ObjectAddedEvent oae = (ObjectAddedEvent)event;
         int oid = oae.getOid();
-        Reference ref = new Reference(target.getOid(), oae.getName(), oid);
+
+        // ensure that the target object exists
+        if (!_objects.contains(oid)) {
+            Log.info("Rejecting object added event of non-existent object " +
+                     "[refferOid=" + target.getOid() +
+                     ", reffedOid=" + oid + "].");
+            return false;
+        }
 
         // get the reference vector for the referenced object. we use bare
         // arrays rather than something like an array list to conserve
@@ -295,12 +316,13 @@ public class CherDObjectMgr implements DObjectManager
         }
 
         // determine where to add the reference
+        Reference ref = new Reference(target.getOid(), oae.getName(), oid);
         int rpos = -1;
         for (int i = 0; i < refs.length; i++) {
             if (ref.equals(refs[i])) {
                 Log.warning("Ignoring request to track existing " +
                             "reference " + ref + ".");
-                return;
+                return true;
             } else if (refs[i] == null && rpos == -1) {
                 rpos = i;
             }
@@ -318,13 +340,17 @@ public class CherDObjectMgr implements DObjectManager
         refs[rpos] = ref;
 
 //          Log.info("Tracked reference " + ref + ".");
+        return true;
     }
 
     /**
      * Called as a helper for <code>ObjectRemovedEvent</code> events. It
      * updates the object/oid list tracking structures.
+     *
+     * @return true if the event should be dispatched, false if it should
+     * be aborted.
      */
-    public void objectRemoved (DEvent event, DObject target)
+    public boolean objectRemoved (DEvent event, DObject target)
     {
         ObjectRemovedEvent ore = (ObjectRemovedEvent)event;
         String field = ore.getName();
@@ -342,7 +368,7 @@ public class CherDObjectMgr implements DObjectManager
 //              Log.warning("Object removed without reference to track it " +
 //                          "[toid=" + toid + ", field=" + field +
 //                          ", oid=" + oid + "].");
-            return;
+            return true;
         }
 
         // look for the matching reference
@@ -350,13 +376,14 @@ public class CherDObjectMgr implements DObjectManager
             if (refs[i].equals(toid, field)) {
 //                  Log.info("Removed reference " + refs[i] + ".");
                 refs[i] = null;
-                return;
+                return true;
             }
         }
 
         Log.warning("Unable to locate reference for removal " +
                     "[reffingOid=" + toid + ", field=" + field +
                     ", reffedOid=" + oid + "].");
+        return true;
     }
 
     protected synchronized boolean isRunning ()

tests/src/java/com/threerings/presents/server/DestroyedRefTest.java

@@ -0,0 +1,77 @@
+//
+// $Id: DestroyedRefTest.java,v 1.1 2001/08/08 21:56:48 mdb Exp $
+
+package com.threerings.cocktail.cher.server.test;
+
+import com.threerings.cocktail.cher.Log;
+import com.threerings.cocktail.cher.dobj.*;
+import com.threerings.cocktail.cher.server.CherServer;
+
+/**
+ * Tests that the dobjmgr will not allow a destroyed object to be added to
+ * an oid list.
+ */
+public class DestroyedRefTest
+    implements Runnable, Subscriber
+{
+    public void run ()
+    {
+        // create two test objects
+        CherServer.omgr.createObject(TestObject.class, this, true);
+        CherServer.omgr.createObject(TestObject.class, this, true);
+    }
+
+    public void objectAvailable (DObject object)
+    {
+        // keep references to our test objects
+        if (_objone == null) {
+            _objone = (TestObject)object;
+
+        } else {
+            _objtwo = (TestObject)object;
+
+            // add object one to object two twice in a row to make sure
+            // repeated adds don't result in the object being listed twice
+            _objtwo.addToList(_objone.getOid());
+            _objtwo.addToList(_objone.getOid());
+
+            // now that we have both objects, try to set up the reference.
+            // first we queue up a destroy event for object two, then we
+            // try to reference it on object one's oid list
+            _objtwo.destroy();
+            _objone.addToList(_objtwo.getOid());
+
+            // finally dispatch an event on which we can trigger our exit
+            _objone.setFoo(1);
+        }
+    }
+
+    public void requestFailed (int oid, ObjectAccessException cause)
+    {
+        Log.warning("Ack. Unable to create object [cause=" + cause + "].");
+    }
+
+    public boolean handleEvent (DEvent event, DObject target)
+    {
+        // when we get the attribute change, we can exit
+        if (event instanceof ObjectDestroyedEvent) {
+            Log.info("The upcoming object added event should be rejected.");
+
+        } else if (event instanceof ObjectAddedEvent &&
+                   target == _objtwo) {
+            Log.info("list should contain only one oid: " + _objtwo.list);
+
+        } else if (event instanceof AttributeChangedEvent) {
+            // go bye bye
+            CherServer.shutdown();
+
+        } else {
+            Log.info("Got unexpected event: " + event);
+        }
+
+        return true;
+    }
+
+    protected TestObject _objone;
+    protected TestObject _objtwo;
+}