OF-1435: Ensure that we start a new thread before calling UserManager… (#942)

* OF-1435: Ensure that we start a new thread before calling UserManager::isRegisteredUser(JID)

* OF-1435: Introduce a Future to highlight that the processing may be performed asynchronously.

src/java/org/jivesoftware/openfire/pubsub/PubSubModule.java

@@ -172,7 +172,7 @@ public class PubSubModule extends BasicModule implements ServerItemsProvider, Di
         try {
             // Check if the packet is a disco request or a packet with namespace iq:register
             if (packet instanceof IQ) {
-                if (!engine.process(this, (IQ) packet)) {
+                if (engine.process(this, (IQ) packet) == null) {
                     process((IQ) packet);
                 }
             }

src/java/org/jivesoftware/openfire/user/UserManager.java

@@ -32,6 +32,7 @@ import org.jivesoftware.openfire.event.UserEventListener;
 import org.jivesoftware.openfire.user.property.DefaultUserPropertyProvider;
 import org.jivesoftware.openfire.user.property.UserPropertyProvider;
 import org.jivesoftware.util.ClassUtils;
+import org.jivesoftware.util.JiveConstants;
 import org.jivesoftware.util.JiveGlobals;
 import org.jivesoftware.util.PropertyEventDispatcher;
 import org.jivesoftware.util.PropertyEventListener;
@@ -411,6 +412,10 @@ public class UserManager implements IQResultListener {
      * remote users (i.e. domain does not match local domain) a disco#info request is going
      * to be sent to the bare JID of the user.
      *
+     * <p>WARNING: If the supplied JID could be a remote user and the disco#info result packet comes back on the same
+     * thread as the one the calls this method then it will not be processed, and this method will block for 60 seconds
+     * by default. To change the timeout, update the system property <code>usermanager.remote-disco-info-timeout-seconds</code>
+     *
      * @param user to JID of the user to check it it's a registered user.
      * @return true if the specified JID belongs to a local or remote registered user.
      */
@@ -444,9 +449,9 @@ public class UserManager implements IQResultListener {
                     server.getIQRouter().addIQResultListener(iq.getID(), this);
                     synchronized (user.toBareJID().intern()) {
                         server.getIQRouter().route(iq);
-                        // Wait for the reply to be processed. Time out in 1 minute.
+                        // Wait for the reply to be processed. Time out in 1 minute by default
                         try {
-                            user.toBareJID().intern().wait(60000);
+                            user.toBareJID().intern().wait(JiveGlobals.getLongProperty("usermanager.remote-disco-info-timeout-seconds", 60) * JiveConstants.SECOND);
                         }
                         catch (InterruptedException e) {
                             // Do nothing

src/java/org/jivesoftware/util/ImmediateFuture.java

+package org.jivesoftware.util;
+
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * A Future that returns immediately.
+ *
+ * @param <T> The type of return value
+ */
+public class ImmediateFuture<T> implements Future<T> {
+
+    private final T value;
+
+    /**
+     * Creates a Future that returns null immediately
+     */
+    public ImmediateFuture() {
+        this(null);
+    }
+
+    /**
+     * Creates a Future that returns the supplied value immediately
+     *
+     * @param value the value to return
+     */
+    public ImmediateFuture(final T value) {
+        this.value = value;
+    }
+
+    @Override
+    public boolean cancel(final boolean mayInterruptIfRunning) {
+        return false;
+    }
+
+    @Override
+    public boolean isCancelled() {
+        return false;
+    }
+
+    @Override
+    public boolean isDone() {
+        return true;
+    }
+
+    @Override
+    public T get() {
+        return value;
+    }
+
+    @Override
+    public T get(final long timeout, final TimeUnit unit) {
+        return value;
+    }
+}