--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.max.graal.compiler/src/com/sun/c1x/observer/ObservableCompiler.java	Wed Jun 08 08:42:25 2011 +0200
@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2011, 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.
+ *
+ * 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 com.sun.c1x.observer;
+
+import java.util.*;
+
+import com.sun.c1x.debug.*;
+
+/**
+ * Base class for compilers that notify subscribed {@link CompilationObserver CompilationObservers} of
+ * {@link CompilationEvent CompilationEvents} that occur during their compilations.
+ *
+ * @author Peter Hofer
+ */
+public class ObservableCompiler {
+
+    private List<CompilationObserver> observers;
+
+    /**
+     * @return {@code true} if one or more observers are subscribed to receive notifications from this compiler,
+     *         {@code false} otherwise.
+     */
+    public boolean isObserved() {
+        return observers != null && !TTY.isSuppressed();
+    }
+
+    /**
+     * Add the specified observer to receive events from this compiler.
+     *
+     * @param observer The observer to add.
+     */
+    public void addCompilationObserver(CompilationObserver observer) {
+        assert observer != null;
+
+        if (observers == null) {
+            observers = new LinkedList<CompilationObserver>();
+        }
+        observers.add(observer);
+    }
+
+    public void fireCompilationStarted(CompilationEvent event) {
+        if (isObserved()) {
+            for (CompilationObserver observer : observers) {
+                observer.compilationStarted(event);
+            }
+        }
+    }
+
+    public void fireCompilationEvent(CompilationEvent event) {
+        if (isObserved()) {
+            for (CompilationObserver observer : observers) {
+                observer.compilationEvent(event);
+            }
+        }
+    }
+
+    public void fireCompilationFinished(CompilationEvent event) {
+        if (isObserved()) {
+            for (CompilationObserver observer : observers) {
+                observer.compilationFinished(event);
+            }
+        }
+    }
+
+    /**
+     * Remove the specified observer so that it no longer receives events from this compiler.
+     *
+     * @param observer The observer to remove.
+     */
+    public void removeCompilationObserver(CompilationObserver observer) {
+        if (observers != null) {
+            observers.remove(observer);
+            if (observers.size() == 0) {
+                observers = null;
+            }
+        }
+    }
+
+}