add: ITriggerable with method trigger() and a TimerTask that triggers based on files being present

SVN: 1901

common/source/java/ch/systemsx/cisd/common/utilities/ITriggerable.java

+/*
+ * Copyright 2007 ETH Zuerich, CISD
+ *
+ * Licensed 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 ch.systemsx.cisd.common.utilities;
+
+/**
+ * A role that allows to trigger some operation.  
+ *
+ * @author Bernd Rinn
+ */
+public interface ITriggerable
+{
+
+    /**
+     * The trigger.
+     */
+    public void trigger();
+    
+}

common/source/java/ch/systemsx/cisd/common/utilities/TriggeringTimerTask.java

+/*
+ * Copyright 2007 ETH Zuerich, CISD
+ *
+ * Licensed 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 ch.systemsx.cisd.common.utilities;
+
+import java.io.File;
+import java.util.TimerTask;
+
+import org.apache.log4j.Logger;
+
+import ch.systemsx.cisd.common.logging.LogCategory;
+import ch.systemsx.cisd.common.logging.LogFactory;
+
+/**
+ * A role that triggers an {@link ITriggerable} when
+ * 
+ * @author Bernd Rinn
+ */
+public class TriggeringTimerTask extends TimerTask
+{
+
+    private static final Logger operationLog = LogFactory.getLogger(LogCategory.OPERATION, TriggeringTimerTask.class);
+
+    private static final Logger notificationLog = LogFactory.getLogger(LogCategory.NOTIFY, TriggeringTimerTask.class);
+
+    private final ITriggerable triggerable;
+
+    private final File triggerFile;
+
+    private final SynchronizationMonitor monitor;
+
+    /**
+     * Creates a <var>TriggeringTimerTask</var>.
+     * 
+     * @param triggerFile The file that triggers.
+     * @param triggerable The handler that can perform a recovery action, or <code>null</code> if there is no recovery
+     *            action available.
+     */
+    public TriggeringTimerTask(File triggerFile, ITriggerable triggerable)
+    {
+        this(triggerFile, triggerable, SynchronizationMonitor.create());
+    }
+
+    /**
+     * Creates a <var>TriggeringTimerTask</var>.
+     * 
+     * @param triggerFile The file that triggers.
+     * @param triggerable The handler that can perform a recovery action, or <code>null</code> if there is no recovery
+     *            action available.
+     * @param monitor The monitor to synchronize on.
+     */
+    public TriggeringTimerTask(File triggerFile, ITriggerable triggerable, SynchronizationMonitor monitor)
+    {
+        assert triggerFile != null;
+        assert triggerable != null;
+        assert monitor != null;
+
+        this.triggerFile = triggerFile;
+        this.triggerable = triggerable;
+        this.monitor = monitor;
+    }
+
+    /**
+     * Handles all entries in the source directory that are picked by the filter.
+     */
+    @Override
+    public synchronized void run()
+    {
+        synchronized(monitor)
+        {
+            try
+            {
+                if (triggerFile.exists())
+                {
+                    trigger();
+                    triggerFile.delete();
+                }
+            } catch (Exception ex)
+            {
+                notificationLog.error("An exception has occurred. (thread still running)", ex);
+            }
+        }
+    }
+
+    private void trigger()
+    {
+        if (triggerable != null)
+        {
+            if (operationLog.isInfoEnabled())
+            {
+                operationLog.info(String.format("File '%s' found - triggering.", triggerFile.getAbsolutePath()));
+            }
+            triggerable.trigger();
+        }
+
+    }
+
+}