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diff --git a/common-logging/src/main/java/org/openecomp/policy/common/logging/flexlogger/PropertyUtil.java b/common-logging/src/main/java/org/openecomp/policy/common/logging/flexlogger/PropertyUtil.java
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+/*-
+ * ============LICENSE_START=======================================================
+ * ECOMP-Logging
+ * ================================================================================
+ * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.openecomp.policy.common.logging.flexlogger;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.Properties;
+import java.util.Set;
+import java.util.Timer;
+import java.util.TimerTask;
+
+/**
+ * This class provides utilities to read properties from a properties
+ * file, and optionally get notifications of future changes
+ */
+public class PropertyUtil
+{
+ /**
+ * Read in a properties file
+ * @param file the properties file
+ * @return a Properties object, containing the associated properties
+ * @throws IOException - subclass 'FileNotFoundException' if the file
+ * does not exist or can't be opened, and 'IOException' if there is
+ * a problem loading the properties file.
+ */
+ static public Properties getProperties(File file) throws IOException
+ {
+ // create an InputStream (may throw a FileNotFoundException)
+ FileInputStream fis = new FileInputStream(file);
+ try
+ {
+ // create the properties instance
+ Properties rval = new Properties();
+
+ // load properties (may throw an IOException)
+ rval.load(fis);
+ return(rval);
+ }
+ finally
+ {
+ // close input stream
+ fis.close();
+ }
+ }
+
+ /**
+ * Read in a properties file
+ * @param fileName the properties file
+ * @return a Properties object, containing the associated properties
+ * @throws IOException - subclass 'FileNotFoundException' if the file
+ * does not exist or can't be opened, and 'IOException' if there is
+ * a problem loading the properties file.
+ */
+ static public Properties getProperties(String fileName) throws IOException
+ {
+ return(getProperties(new File(fileName)));
+ }
+
+ /* ============================================================ */
+
+ // timer thread used for polling for property file changes
+ private static Timer timer = null;
+
+ /**
+ * This is the callback interface, used for sending notifications of
+ * changes in the properties file.
+ */
+ public interface Listener
+ {
+ /**
+ * Notification of a properties file change
+ * @param properties the new properties
+ * @param the set of property names that have changed, including
+ * additions and removals
+ */
+ void propertiesChanged(Properties properties, Set<String> changedKeys);
+ }
+
+ // this table maps canonical file into a 'ListenerRegistration' instance
+ static private HashMap<File, ListenerRegistration> registrations =
+ new HashMap<File, ListenerRegistration>();
+
+ /**
+ * This is an internal class - one instance of this exists for each
+ * property file that is being monitored. Note that multiple listeners
+ * can be registered for the same file.
+ */
+ private static class ListenerRegistration
+ {
+ // the canonical path of the file being monitored
+ File file;
+
+ // the most recent value of 'file.lastModified()'
+ long lastModified;
+
+ // the most recent set of properties
+ Properties properties;
+
+ // the set of listeners monitoring this file
+ LinkedList<Listener> listeners;
+
+ // the 'TimerTask' instance, used for periodic polling
+ TimerTask timerTask;
+
+ /**
+ * Constructor - create a 'ListenerRegistration' instance for this
+ * file, but with no listeners
+ */
+ ListenerRegistration(File file) throws IOException
+ {
+ this.file = file;
+
+ // The initial value of 'lastModified' is set to 0 to ensure that we
+ // correctly handle the case where the file is modified within the
+ // same second that polling begins.
+ lastModified = 0;
+
+ // fetch current properties
+ properties = getProperties(file);
+
+ // no listeners yet
+ listeners = new LinkedList<Listener>();
+
+ // add to static table, so this instance can be shared
+ registrations.put(file, this);
+
+ if (timer == null)
+ {
+ // still need to create a timer thread
+ synchronized(PropertyUtil.class)
+ {
+ // an additional check is added inside the 'synchronized' block,
+ // just in case someone beat us to it
+ if (timer == null)
+ {
+ timer = new Timer("PropertyUtil-Timer", true);
+ }
+ }
+ }
+
+ // create and schedule the timer task, so this is periodically polled
+ timerTask = new TimerTask()
+ {
+ public void run()
+ {
+ try
+ {
+ poll();
+ }
+ catch (Exception e)
+ {
+ System.err.println(e);
+ }
+ }
+ };
+ timer.schedule(timerTask, 10000L, 10000L);
+ }
+
+ /**
+ * Add a listener to the notification list
+ * @param listener this is the listener to add to the list
+ * @return the properties at the moment the listener was added to the list
+ */
+ synchronized Properties addListener(Listener listener)
+ {
+ listeners.add(listener);
+ return((Properties)properties.clone());
+ }
+
+ /**
+ * Remove a listener from the notification list
+ * @param listener this is the listener to remove
+ */
+ synchronized void removeListener(Listener listener)
+ {
+ listeners.remove(listener);
+
+ // See if we need to remove this 'ListenerRegistration' instance
+ // from the table. The 'synchronized' block is needed in case
+ // another listener is being added at about the same time that this
+ // one is being removed.
+ synchronized(registrations)
+ {
+ if (listeners.size() == 0)
+ {
+ timerTask.cancel();
+ registrations.remove(file);
+ }
+ }
+ }
+
+ /**
+ * This method is periodically called to check for property list updates
+ * @throws IOException if there is an error in reading the properties file
+ */
+ synchronized void poll() throws IOException
+ {
+ long timestamp = file.lastModified();
+ if (timestamp != lastModified)
+ {
+ // update the record, and send out the notifications
+ lastModified = timestamp;
+
+ // Save old set, and initial set of changed properties.
+ Properties oldProperties = properties;
+ HashSet<String> changedProperties =
+ new HashSet<String>(oldProperties.stringPropertyNames());
+
+ // Fetch the list of listeners that we will potentially notify,
+ // and the new properties. Note that this is in a 'synchronized'
+ // block to ensure that all listeners receiving notifications
+ // actually have a newer list of properties than the one
+ // returned on the initial 'getProperties' call.
+ properties = getProperties(file);
+
+ Set<String> newPropertyNames = properties.stringPropertyNames();
+ changedProperties.addAll(newPropertyNames);
+
+ // At this point, 'changedProperties' is the union of all properties
+ // in both the old and new properties files. Iterate through all
+ // of the entries in the new properties file - if the entry
+ // matches the one in the old file, remove it from
+ // 'changedProperties'.
+ for (String name : newPropertyNames)
+ {
+ if (properties.getProperty(name).equals
+ (oldProperties.getProperty(name)))
+ {
+ // Apparently, any property that exists must be of type
+ // 'String', and can't be null. For this reason, we don't
+ // need to worry about the case where
+ // 'properties.getProperty(name)' returns 'null'. Note that
+ // 'oldProperties.getProperty(name)' may be 'null' if the
+ // old property does not exist.
+ changedProperties.remove(name);
+ }
+ }
+
+ // 'changedProperties' should be correct at this point
+ if (changedProperties.size() != 0)
+ {
+ // there were changes - notify everyone in 'listeners'
+ for (final Listener notify : listeners)
+ {
+ // Copy 'properties' and 'changedProperties', so it doesn't
+ // cause problems if the recipient makes changes.
+ final Properties tmpProperties =
+ (Properties)(properties.clone());
+ final HashSet<String> tmpChangedProperties =
+ new HashSet<String>(changedProperties);
+
+ // Do the notification in a separate thread, so blocking
+ // won't cause any problems.
+ new Thread()
+ {
+ public void run()
+ {
+ notify.propertiesChanged
+ (tmpProperties, tmpChangedProperties);
+ }
+ }.start();
+ }
+ }
+ }
+ }
+ }
+
+ /**
+ * Read in a properties file, and register for update notifications.
+ * NOTE: it is possible that the first callback will occur while this
+ * method is still in progress. To avoid this problem, use 'synchronized'
+ * blocks around this invocation and in the callback -- that will ensure
+ * that the processing of the initial properties complete before any
+ * updates are processed.
+ *
+ * @param file the properties file
+ * @param notify if not null, this is a callback interface that is used for
+ * notifications of changes
+ * @return a Properties object, containing the associated properties
+ * @throws IOException - subclass 'FileNotFoundException' if the file
+ * does not exist or can't be opened, and 'IOException' if there is
+ * a problem loading the properties file.
+ */
+ static public Properties getProperties(File file, Listener listener)
+ throws IOException
+ {
+ if (listener == null)
+ {
+ // no listener specified -- just fetch the properties
+ return(getProperties(file));
+ }
+
+ // Convert the file to a canonical form in order to avoid the situation
+ // where different names refer to the same file.
+ file = file.getCanonicalFile();
+
+ // See if there is an existing registration. The 'synchronized' block
+ // is needed to handle the case where a new listener is added at about
+ // the same time that another one is being removed.
+ synchronized(registrations)
+ {
+ ListenerRegistration reg = registrations.get(file);
+ if (reg == null)
+ {
+ // a new registration is needed
+ reg = new ListenerRegistration(file);
+ }
+ return(reg.addListener(listener));
+ }
+ }
+
+ /**
+ * Read in a properties file, and register for update notifications.
+ * NOTE: it is possible that the first callback will occur while this
+ * method is still in progress. To avoid this problem, use 'synchronized'
+ * blocks around this invocation and in the callback -- that will ensure
+ * that the processing of the initial properties complete before any
+ * updates are processed.
+ *
+ * @param fileName the properties file
+ * @param notify if not null, this is a callback interface that is used for
+ * notifications of changes
+ * @return a Properties object, containing the associated properties
+ * @throws IOException - subclass 'FileNotFoundException' if the file
+ * does not exist or can't be opened, and 'IOException' if there is
+ * a problem loading the properties file.
+ */
+ static public Properties getProperties(String fileName, Listener listener)
+ throws IOException
+ {
+ return(getProperties(new File(fileName), listener));
+ }
+
+ /**
+ * Stop listenening for updates
+ * @param file the properties file
+ * @param notify if not null, this is a callback interface that was used for
+ * notifications of changes
+ */
+ static public void stopListening(File file, Listener listener)
+ {
+ if (listener != null)
+ {
+ ListenerRegistration reg = registrations.get(file);
+ if (reg != null)
+ {
+ reg.removeListener(listener);
+ }
+ }
+ }
+
+ /**
+ * Stop listenening for updates
+ * @param fileName the properties file
+ * @param notify if not null, this is a callback interface that was used for
+ * notifications of changes
+ */
+ static public void stopListening(String fileName, Listener listener)
+ {
+ stopListening(new File(fileName), listener);
+ }
+
+ /* ============================================================ */
+
+ // TEMPORARY - used to test callback interface
+ static public class Test implements Listener
+ {
+ String name;
+
+ public Test(String name)
+ {
+ this.name = name;
+ }
+
+ public void propertiesChanged(Properties properties, Set<String> changedKeys)
+ {
+ System.out.println("Test(" + name + ")\nproperties = " + properties
+ + "\nchangedKeys = " + changedKeys);
+ }
+ }
+}