Merge pull request #869 from grgrzybek/jetty-9.2.x-868

Issue #868 - Use static Throwables without backtrace/stackTrace

jetty-continuation/src/main/java/org/eclipse/jetty/continuation/ContinuationThrowable.java

@@ -43,4 +43,9 @@ package org.eclipse.jetty.continuation;
  * </p>
  */
 public class ContinuationThrowable extends Error
-{}
+{
+    public ContinuationThrowable()
+    {
+        super(null, null, false, false);
+    }
+}

jetty-util/src/main/java/org/eclipse/jetty/util/BlockingCallback.java

@@ -36,11 +36,7 @@ public class BlockingCallback implements Callback
 {
     private static final Logger LOG = Log.getLogger(BlockingCallback.class);
     
-    private static Throwable SUCCEEDED=new Throwable()
-    {
-        @Override
-        public String toString() { return "SUCCEEDED"; }
-    };
+    private static Throwable SUCCEEDED = new ConstantThrowable("SUCCEEDED");
     
     private final CountDownLatch _latch = new CountDownLatch(1);
     private final AtomicReference<Throwable> _state = new AtomicReference<>();

jetty-util/src/main/java/org/eclipse/jetty/util/ConstantThrowable.java

@@ -0,0 +1,43 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.util;
+
+/**
+ * A {@link Throwable} that may be used in static contexts. It uses Java 7
+ * constructor that prevents setting stackTrace inside exception object.
+ */
+public class ConstantThrowable extends Throwable {
+
+    private String name;
+
+    public ConstantThrowable() {
+        this(null);
+    }
+
+    public ConstantThrowable(String name) {
+        super(null, null, false, false);
+        this.name = name;
+    }
+
+    @Override
+    public String toString() {
+        return name;
+    }
+
+}

jetty-util/src/main/java/org/eclipse/jetty/util/FutureCallback.java

@@ -29,7 +29,7 @@ import java.util.concurrent.atomic.AtomicBoolean;
 
 public class FutureCallback implements Future<Void>,Callback
 {
-    private static Throwable COMPLETED=new Throwable();
+    private static Throwable COMPLETED=new ConstantThrowable();
     private final AtomicBoolean _done=new AtomicBoolean(false);
     private final CountDownLatch _latch=new CountDownLatch(1);
     private Throwable _cause;

jetty-util/src/main/java/org/eclipse/jetty/util/FuturePromise.java

@@ -29,7 +29,7 @@ import java.util.concurrent.atomic.AtomicBoolean;
 
 public class FuturePromise<C> implements Future<C>,Promise<C>
 {
-    private static Throwable COMPLETED=new Throwable();
+    private static Throwable COMPLETED=new ConstantThrowable();
     private final AtomicBoolean _done=new AtomicBoolean(false);
     private final CountDownLatch _latch=new CountDownLatch(1);
     private Throwable _cause;

jetty-util/src/main/java/org/eclipse/jetty/util/SharedBlockingCallback.java

@@ -54,33 +54,12 @@ public class SharedBlockingCallback
     final Condition _idle = _lock.newCondition();
     final Condition _complete = _lock.newCondition();
 
-    
-    private static Throwable IDLE = new Throwable()
-    {
-        @Override
-        public String toString()
-        {
-            return "IDLE";
-        }
-    };
 
-    private static Throwable SUCCEEDED = new Throwable()
-    {
-        @Override
-        public String toString()
-        {
-            return "SUCCEEDED";
-        }
-    };
-    
-    private static Throwable FAILED = new Throwable()
-    {
-        @Override
-        public String toString()
-        {
-            return "FAILED";
-        }
-    };
+    private static Throwable IDLE = new ConstantThrowable("IDLE");
+
+    private static Throwable SUCCEEDED = new ConstantThrowable("SUCCEEDED");
+
+    private static Throwable FAILED = new ConstantThrowable("FAILED");
 
     Blocker _blocker;