From 27a3ceeb27a7178fa6f5a9504636d2ab1987dd1c Mon Sep 17 00:00:00 2001
From: Greg Wilkins <gregw@intalio.com>
Date: Thu, 17 Oct 2013 12:43:28 +1100
Subject: [PATCH] Optimised SelectorManager to avoid changeQ for interest ops

---
 .../jetty/io/SelectChannelEndPoint.java       |  3 +-
 .../org/eclipse/jetty/io/SelectorManager.java | 36 +++++++++++++++++++
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/jetty-io/src/main/java/org/eclipse/jetty/io/SelectChannelEndPoint.java b/jetty-io/src/main/java/org/eclipse/jetty/io/SelectChannelEndPoint.java
index 7f012d9dc1d..b3bf8e8a9a7 100644
--- a/jetty-io/src/main/java/org/eclipse/jetty/io/SelectChannelEndPoint.java
+++ b/jetty-io/src/main/java/org/eclipse/jetty/io/SelectChannelEndPoint.java
@@ -133,7 +133,7 @@ public class SelectChannelEndPoint extends ChannelEndPoint implements SelectorMa
                 if (_interestOps.compareAndSet(oldInterestOps, newInterestOps))
                 {
                     LOG.debug("Local interests updated {} -> {} for {}", oldInterestOps, newInterestOps, this);
-                    _selector.submit(_updateTask);
+                    _selector.updateKey(_updateTask);
                 }
                 else
                 {
@@ -152,7 +152,6 @@ public class SelectChannelEndPoint extends ChannelEndPoint implements SelectorMa
 
     private void setKeyInterests(int oldInterestOps, int newInterestOps)
     {
-        assert _selector.isSelectorThread();
         LOG.debug("Key interests updated {} -> {}", oldInterestOps, newInterestOps);
         _key.interestOps(newInterestOps);
     }
diff --git a/jetty-io/src/main/java/org/eclipse/jetty/io/SelectorManager.java b/jetty-io/src/main/java/org/eclipse/jetty/io/SelectorManager.java
index f14c3b950b4..f711ce6e4f3 100644
--- a/jetty-io/src/main/java/org/eclipse/jetty/io/SelectorManager.java
+++ b/jetty-io/src/main/java/org/eclipse/jetty/io/SelectorManager.java
@@ -59,11 +59,14 @@ import org.eclipse.jetty.util.thread.Scheduler;
 public abstract class SelectorManager extends AbstractLifeCycle implements Dumpable
 {
     protected static final Logger LOG = Log.getLogger(SelectorManager.class);
+    
     /**
      * The default connect timeout, in milliseconds
      */
     public static final int DEFAULT_CONNECT_TIMEOUT = 15000;
 
+    private final static boolean __submitKeyUpdates=Boolean.valueOf(System.getProperty("org.eclipse.jetty.io.SelectorManager.SubmitKeyUpdates","FALSE"));
+    
     private final Executor executor;
     private final Scheduler scheduler;
     private final ManagedSelector[] _selectors;
@@ -356,6 +359,39 @@ public abstract class SelectorManager extends AbstractLifeCycle implements Dumpa
             LOG.debug("Stopped {}", this);
         }
 
+        /**
+         * Submit a task to update a selector key.  If the System property
+         * "org.eclipse.jetty.io.SelectorManager.SubmitKeyUpdates" is set true (default is false), the
+         * task is passed to {@link #submit(Runnable)}.   Otherwise it is run immediately and the selector 
+         * woken up if need be.   
+         * @param update the update to a key
+         */
+        public void updateKey(Runnable update)
+        {
+            if (__submitKeyUpdates)
+                submit(update);
+            else
+            {
+                update.run();
+
+                out: while (true)
+                {
+                    switch (_state.get())
+                    {
+                        case SELECT:
+                            // Avoid multiple wakeup() calls if we the CAS fails
+                            if (!_state.compareAndSet(State.SELECT, State.WAKEUP))
+                                continue;
+                            wakeup();
+                            break out;
+                        default:
+                            break out;
+                    }
+                }
+            }
+            
+        }
+        
         /**
          * <p>Submits a change to be executed in the selector thread.</p>
          * <p>Changes may be submitted from any thread, and the selector thread woken up