AMQ-5709 Reworking Logging on Locker

https://issues.apache.org/jira/browse/AMQ-5709

This is about changing how the Log is done in case of not being able to lock (log only once)

activemq-broker/src/main/java/org/apache/activemq/store/SharedFileLocker.java

@@ -16,15 +16,15 @@
  */
 package org.apache.activemq.store;
 
+import java.io.File;
+import java.io.IOException;
+
 import org.apache.activemq.broker.AbstractLocker;
 import org.apache.activemq.util.LockFile;
 import org.apache.activemq.util.ServiceStopper;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.io.File;
-import java.io.IOException;
-
 /**
  * Represents an exclusive lock on a database to avoid multiple brokers running
  * against the same logical database.
@@ -48,14 +48,25 @@ public class SharedFileLocker extends AbstractLocker {
             if (failIfLocked) {
                 lockFile.lock();
             } else {
+                // Print a warning only once
+                boolean warned = false;
                 boolean locked = false;
                 while ((!isStopped()) && (!isStopping())) {
                     try {
                         lockFile.lock();
                         locked = keepAlive();
+                        LOG.info("locked " + locked);
                         break;
                     } catch (IOException e) {
+                        if (!warned)
+                        {
                             LOG.info("Database "
+                                         + lockFileName
+                                         + " is locked by another server. This broker is now in slave mode waiting a lock to be acquired");
+                            warned = true;
+                        }
+
+                        LOG.debug("Database "
                                     + lockFileName
                                     + " is locked... waiting "
                                     + (lockAcquireSleepInterval / 1000)

activemq-unit-tests/src/test/java/org/apache/activemq/store/SharedFileLockerTest.java

@@ -0,0 +1,109 @@
+/**
+ * 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.activemq.store;
+
+import java.io.File;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.junit.Assert;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+public class SharedFileLockerTest
+{
+   @Rule
+   public TemporaryFolder testFolder = new TemporaryFolder();
+
+   @Test
+   public void testLock() throws Exception
+   {
+      final AtomicInteger errors = new AtomicInteger(0);
+
+      Thread thread = null;
+
+      SharedFileLocker locker1 = new SharedFileLocker();
+      locker1.setDirectory(testFolder.getRoot());
+
+      final SharedFileLocker locker2 = new SharedFileLocker();
+      locker2.setLockAcquireSleepInterval(1);
+      locker2.setDirectory(testFolder.getRoot());
+
+
+      try
+      {
+         locker1.doStart();
+
+         Assert.assertTrue(locker1.keepAlive());
+
+         Thread.sleep(10);
+
+         thread = new Thread("Locker Thread")
+         {
+            public void run()
+            {
+               try
+               {
+                  locker2.doStart();
+               }
+               catch (Throwable e)
+               {
+                  errors.incrementAndGet();
+               }
+            }
+         };
+
+         thread.start();
+
+         // Waiting some small time here, you shouldn't see many messages
+         Thread.sleep(100);
+
+         Assert.assertTrue(thread.isAlive());
+
+         locker1.stop();
+
+         // 10 seconds here is an eternity, but it should only take milliseconds
+         thread.join(5000);
+
+         long timeout = System.currentTimeMillis() + 5000;
+
+         while (timeout > System.currentTimeMillis() && !locker2.keepAlive())
+         {
+            Thread.sleep(1);
+         }
+
+         Assert.assertTrue(locker2.keepAlive());
+
+         locker2.stop();
+
+      }
+      finally
+      {
+         // to make sure we won't leak threads if the test ever failed for any reason
+         thread.join(1000);
+         if (thread.isAlive())
+         {
+            thread.interrupt();
+         }
+
+         File lockFile = new File(testFolder.getRoot(), "lock");
+         lockFile.delete();
+      }
+
+   }
+}