Fixes for shutdown sequence, including prevention of a race condition

* Throw an exception if any events, runnables or messages are posted after shutdown. These were previosuly being silently ignored. We really should know about them.
* Don't exit the connection manager thread until the object manager thread exits. This fixes a race condition where the wakeup time of the conmgr thread would determine if it shutdown before or after the object manager, meaning it would sometimes ignore messages around shutdown time.
* Add a shutdown constraint to make the client manager shutdown before the invoker/event/conmgr threads. This gives a single point in the shutdown sequence that applications can use as a constraint (TODO: shutdown groups?)
* Emit a log message for each shutdown method call. This could be very useful in production.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@5491 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/presents/server/net/ConnectionManager.java

@@ -255,6 +255,13 @@ public class ConnectionManager extends LoopingThread
         report.append(avgOut).append(" avg size, ");
         report.append(bytesOut*1000/sinceLast).append(" bps\n");
     }
+    
+    @Override // from LoopingThread
+    public boolean isRunning ()
+    {
+        // Prevent exiting our thread until the object manager is done.
+        return super.isRunning() || _omgr.isRunning();
+    }
 
     /**
      * Notifies the connection observers of a connection event. Used internally.
@@ -722,6 +729,9 @@ public class ConnectionManager extends LoopingThread
         sendOutgoingMessages(System.currentTimeMillis());
 
         // unbind our listening socket
+        // Note: because we wait for the object manager to exit before we do, we will still be
+        // accepting connections as long as there are events pending.
+        // TODO: consider shutting down the listen socker earlier, like in the shutdown method
         try {
             _ssocket.socket().close();
         } catch (IOException ioe) {
@@ -846,6 +856,10 @@ public class ConnectionManager extends LoopingThread
      */
     void postMessage (Connection conn, DownstreamMessage msg)
     {
+        if (!isRunning()) {
+            throw new IllegalStateException("Connection manager has been shutdown");
+        }
+        
         // sanity check
         if (conn == null || msg == null) {
             log.warning("postMessage() bogosity", "conn", conn, "msg", msg, new Exception());