1 files changed, 124 insertions, 0 deletions
diff --git a/trunk/qpid/java/systests/src/main/java/org/apache/qpid/test/framework/clocksynch/ClockSynchThread.java b/trunk/qpid/java/systests/src/main/java/org/apache/qpid/test/framework/clocksynch/ClockSynchThread.java
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index 0000000000..3d4c4f7d12
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+++ b/trunk/qpid/java/systests/src/main/java/org/apache/qpid/test/framework/clocksynch/ClockSynchThread.java
@@ -0,0 +1,124 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+package org.apache.qpid.test.framework.clocksynch;
+
+import org.apache.log4j.Logger;
+
+import org.apache.qpid.junit.extensions.ShutdownHookable;
+import org.apache.qpid.junit.extensions.Throttle;
+
+/**
+ * ClockSynchThread is a convenient utility for running a thread that periodically synchronizes the clock against
+ * a reference. Supply it with a {@link ClockSynchronizer} and a {@link Throttle} and it will continually keep the
+ * clock up-to-date at a rate determined by the throttle.
+ *
+ * <p/><table id="crc"><caption>CRC Card</caption>
+ * <tr><th> Responsibilities <th> Collaborations
+ * <tr><td> Continually sychronize the clock at a throttled rate.
+ * </table>
+ */
+public class ClockSynchThread extends Thread implements ShutdownHookable
+{
+    /** Used for debugging. */
+    private static final Logger log = Logger.getLogger(ClockSynchThread.class);
+
+    /** Holds the clock syncher for the synch thread. */
+    private ClockSynchronizer clockSyncher;
+
+    /** Holds the throttle to limit the synch rate. */
+    private Throttle throttle;
+
+    /** Flag to indicate that the periodic clock syncher should keep running. */
+    boolean doSynch = true;
+
+    /**
+     * Creates a clock synchronizer thread from a clock synchronizer and a throttle.
+     *
+     * @param syncher  The clock synchronizer.
+     * @param throttle The throttle.
+     */
+    public ClockSynchThread(ClockSynchronizer syncher, Throttle throttle)
+    {
+        this.clockSyncher = syncher;
+        this.throttle = throttle;
+    }
+
+    /**
+     * Terminates the synchronization thread.
+     */
+    public void terminate()
+    {
+        doSynch = false;
+    }
+
+    /**
+     * Continually updates the clock, until {@link #terminate()} is called.
+     */
+    public void run()
+    {
+        while (doSynch)
+        {
+            // Perform a clock clockSynch.
+            try
+            {
+                // Wait controlled by the throttle before doing the next synch.
+                throttle.throttle();
+
+                clockSyncher.synch();
+                log.debug("Clock synched, delta = " + clockSyncher.getDelta() + ", epsilon = " + clockSyncher.getEpsilon()
+                    + ".");
+            }
+            // Terminate the synch thread if the synchronization cannot be achieved.
+            catch (ClockSynchFailureException e)
+            {
+                log.debug("Cannot synchronize the clock (reference service may be down). Terminating the synch thread.");
+                doSynch = false;
+            }
+        }
+    }
+
+    /**
+     * Gets the clock synchronizer that is kept continually up to date.
+     *
+     * @return The clock synchronizer that is kept continually up to date.
+     */
+    public ClockSynchronizer getClockSyncher()
+    {
+        return clockSyncher;
+    }
+
+    /**
+     * Supplies a shutdown hook, that terminates the synching thread.
+     *
+     * @return The shut down hook.
+     */
+    public Thread getShutdownHook()
+    {
+        return new Thread(new Runnable()
+                {
+                    public void run()
+                    {
+                        doSynch = false;
+                    }
+                });
+    }
+}
+