--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/src/jdk.jshell/share/classes/jdk/internal/jshell/jdi/FailOverExecutionControl.java	Thu Jun 02 14:05:13 2016 -0700
@@ -0,0 +1,119 @@
+/*
+ * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code 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 General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package jdk.internal.jshell.jdi;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import jdk.internal.jshell.debug.InternalDebugControl;
+import jdk.jshell.JShellException;
+import jdk.jshell.spi.ExecutionControl;
+import jdk.jshell.spi.ExecutionEnv;
+
+/**
+ * A meta implementation of ExecutionControl which cycles through the specified
+ * ExecutionControl instances until it finds one that starts.
+ */
+public class FailOverExecutionControl implements ExecutionControl {
+
+    private final List<ExecutionControl> ecl = new ArrayList<>();
+    private ExecutionControl active = null;
+    private final List<Exception> thrown = new ArrayList<>();
+
+    /**
+     * Create the ExecutionControl instance with at least one actual
+     * ExecutionControl instance.
+     *
+     * @param ec0 the first instance to try
+     * @param ecs the second and on instance to try
+     */
+    public FailOverExecutionControl(ExecutionControl ec0, ExecutionControl... ecs) {
+        ecl.add(ec0);
+        for (ExecutionControl ec : ecs) {
+            ecl.add(ec);
+        }
+    }
+
+    @Override
+    public void start(ExecutionEnv env) throws Exception {
+        for (ExecutionControl ec : ecl) {
+            try {
+                ec.start(env);
+                // Success! This is our active ExecutionControl
+                active = ec;
+                return;
+            } catch (Exception ex) {
+                thrown.add(ex);
+            } catch (Throwable ex) {
+                thrown.add(new RuntimeException(ex));
+            }
+            InternalDebugControl.debug(env.state(), env.userErr(),
+                    thrown.get(thrown.size() - 1), "failed one in FailOverExecutionControl");
+        }
+        // They have all failed -- rethrow the first exception we encountered
+        throw thrown.get(0);
+    }
+
+    @Override
+    public void close() {
+        active.close();
+    }
+
+    @Override
+    public boolean addToClasspath(String path) {
+        return active.addToClasspath(path);
+    }
+
+    @Override
+    public String invoke(String classname, String methodname) throws JShellException {
+        return active.invoke(classname, methodname);
+    }
+
+    @Override
+    public boolean load(Collection<String> classes) {
+        return active.load(classes);
+    }
+
+    @Override
+    public boolean redefine(Collection<String> classes) {
+        return active.redefine(classes);
+    }
+
+    @Override
+    public ClassStatus getClassStatus(String classname) {
+        return active.getClassStatus(classname);
+    }
+
+    @Override
+    public void stop() {
+        active.stop();
+    }
+
+    @Override
+    public String varValue(String classname, String varname) {
+        return active.varValue(classname, varname);
+    }
+
+}