From beacb948b1e78ca3d32f6dfc2fddc687d41ce151 Mon Sep 17 00:00:00 2001
From: Greg Wilkins <gregw@intalio.com>
Date: Thu, 1 Jan 2015 17:04:00 +0100
Subject: [PATCH] Allow configuration of ExecutionStrategy

eg -Dorg.eclipse.jetty.io.ManagedSelector.ExecutionStrategy=org.eclipse.jetty.util.thread.ExecutionStrategy$ExecuteProduceRun
---
 .../eclipse/jetty/http2/HTTP2Connection.java  |  2 +-
 .../org/eclipse/jetty/io/ManagedSelector.java |  2 +-
 .../jetty/util/thread/ExecutionStrategy.java  | 30 +++++++++++++++++++
 3 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/jetty-http2/http2-common/src/main/java/org/eclipse/jetty/http2/HTTP2Connection.java b/jetty-http2/http2-common/src/main/java/org/eclipse/jetty/http2/HTTP2Connection.java
index 0b97cb53e18..33fe41ae481 100644
--- a/jetty-http2/http2-common/src/main/java/org/eclipse/jetty/http2/HTTP2Connection.java
+++ b/jetty-http2/http2-common/src/main/java/org/eclipse/jetty/http2/HTTP2Connection.java
@@ -51,7 +51,7 @@ public class HTTP2Connection extends AbstractConnection
         this.parser = parser;
         this.session = session;
         this.bufferSize = bufferSize;
-        this.executionStrategy = new ExecutionStrategy.ExecuteProduceRun(new HTTP2Producer(), executor);
+        this.executionStrategy = ExecutionStrategy.Factory.instanceFor(new HTTP2Producer(), executor);
     }
 
     protected ISession getSession()
diff --git a/jetty-io/src/main/java/org/eclipse/jetty/io/ManagedSelector.java b/jetty-io/src/main/java/org/eclipse/jetty/io/ManagedSelector.java
index 31ce76ab766..d473ac858dd 100644
--- a/jetty-io/src/main/java/org/eclipse/jetty/io/ManagedSelector.java
+++ b/jetty-io/src/main/java/org/eclipse/jetty/io/ManagedSelector.java
@@ -68,7 +68,7 @@ public class ManagedSelector extends AbstractLifeCycle implements Runnable, Dump
     public ManagedSelector(SelectorManager selectorManager, int id)
     {
         _selectorManager = selectorManager;
-        _strategy = new ExecutionStrategy.ExecuteProduceRun(this, selectorManager.getExecutor());
+        _strategy = ExecutionStrategy.Factory.instanceFor(this, selectorManager.getExecutor());
         _id = id;
         setStopTimeout(5000);
     }
diff --git a/jetty-util/src/main/java/org/eclipse/jetty/util/thread/ExecutionStrategy.java b/jetty-util/src/main/java/org/eclipse/jetty/util/thread/ExecutionStrategy.java
index f98079ce065..88e0392894a 100644
--- a/jetty-util/src/main/java/org/eclipse/jetty/util/thread/ExecutionStrategy.java
+++ b/jetty-util/src/main/java/org/eclipse/jetty/util/thread/ExecutionStrategy.java
@@ -18,9 +18,12 @@
 
 package org.eclipse.jetty.util.thread;
 
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Method;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicReference;
 
+import org.eclipse.jetty.util.Loader;
 import org.eclipse.jetty.util.log.Log;
 import org.eclipse.jetty.util.log.Logger;
 
@@ -56,6 +59,33 @@ public interface ExecutionStrategy
         Runnable produce();
     }
 
+    public static class Factory
+    {
+        private static final Logger LOG = Log.getLogger(Factory.class);
+
+        public static ExecutionStrategy instanceFor(Producer producer, Executor executor)
+        {
+            // TODO remove this mechanism before release
+            String strategy = System.getProperty(producer.getClass().getName()+".ExecutionStrategy");
+            if (strategy!=null)
+            {
+                try
+                {
+                    Class<? extends ExecutionStrategy> c = Loader.loadClass(producer.getClass(),strategy);
+                    Constructor<? extends ExecutionStrategy> m = c.getConstructor(Producer.class,Executor.class);
+                    LOG.info("Use {} for {}",c.getSimpleName(),producer.getClass().getName());
+                    return  m.newInstance(producer,executor);
+                }
+                catch(Exception e)
+                {
+                    LOG.warn(e);
+                }
+            }
+            
+            return new ExecuteProduceRun(producer,executor);
+        }
+    }
+    
     /**
      * <p>A strategy where the caller thread iterates over task production, submitting each
      * task to an {@link Executor} for execution.</p>