Holy fruity beverage Batman! I'm taking the plunge and switching to Guice for

dependency resolution and management. Things are currently in a state of
transition, but the important patterns have been established and I'll aim to
sweep through all of Narya, Nenya and Vilya in the near future and do
everything properly.

Going through the other million-odd lines of code we have scattered across our
various projects that use these libraries is not something I plan to do, so
we'll be maintaining backward compatibility with the old static member method,
though I hope to strive toward eradication of that usage entirely in MSOY while
we still have a fighting chance.

Given that some of our projects will continue to use the static member method
in perpetuity, I'm not going to @Deprecate those fields because that would fill
their logs with so much spam that they'd have to turn off deprecation warnings
which would make life worse for them. So instead we'll settle for the big scary
comment warning people away from the old bits.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@5153 542714f4-19e9-0310-aa3c-eee0fc999fb1

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

@@ -0,0 +1,81 @@
+//
+// $Id$
+//
+// Narya library - tools for developing networked games
+// Copyright (C) 2002-2008 Three Rings Design, Inc., All Rights Reserved
+// http://www.threerings.net/code/narya/
+//
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.threerings.presents.server;
+
+import com.google.inject.Singleton;
+
+import com.samskivert.util.ObserverList;
+
+import static com.threerings.presents.Log.log;
+
+/**
+ * Handles the orderly shutdown of all server services.
+ */
+@Singleton
+public class ShutdownManager
+{
+    /** Implementers of this interface will be notified when the server is shutting down. */
+    public static interface Shutdowner
+    {
+        /**
+         * Called when the server is shutting down.
+         */
+        public void shutdown ();
+    }
+
+    /**
+     * Registers an entity that will be notified when the server is shutting down.
+     */
+    public void registerShutdowner (Shutdowner downer)
+    {
+        _downers.add(downer);
+    }
+
+    /**
+     * Unregisters the shutdowner from hearing when the server is shutdown.
+     */
+    public void unregisterShutdowner (Shutdowner downer)
+    {
+        _downers.remove(downer);
+    }
+
+    public void shutdown ()
+    {
+        ObserverList<Shutdowner> downers = _downers;
+        if (downers == null) {
+            log.warning("Refusing repeat shutdown request.");
+            return;
+        }
+        _downers = null;
+
+        // shut down all shutdown participants
+        downers.apply(new ObserverList.ObserverOp<Shutdowner>() {
+            public boolean apply (Shutdowner downer) {
+                downer.shutdown();
+                return true;
+            }
+        });
+    }
+
+    /** A list of shutdown participants. */
+    protected static ObserverList<Shutdowner> _downers = ObserverList.newSafeInOrder();
+}