diff options
Diffstat (limited to 'common-logging/src/main/java/org/onap/policy/common/logging/flexlogger/PropertyUtil.java')
| -rw-r--r-- | common-logging/src/main/java/org/onap/policy/common/logging/flexlogger/PropertyUtil.java | 667 |
1 files changed, 310 insertions, 357 deletions
diff --git a/common-logging/src/main/java/org/onap/policy/common/logging/flexlogger/PropertyUtil.java b/common-logging/src/main/java/org/onap/policy/common/logging/flexlogger/PropertyUtil.java index 86d119ea..54e06411 100644 --- a/common-logging/src/main/java/org/onap/policy/common/logging/flexlogger/PropertyUtil.java +++ b/common-logging/src/main/java/org/onap/policy/common/logging/flexlogger/PropertyUtil.java @@ -2,7 +2,7 @@ * ============LICENSE_START======================================================= * ONAP-Logging * ================================================================================ - * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved. + * Copyright (C) 2017-2018 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. @@ -32,360 +32,313 @@ 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 + * This class provides utilities to read properties from a properties file, and optionally get + * notifications of future changes. */ -public class PropertyUtil -{ - - // timer thread used for polling for property file changes - private static Timer timer = null; - - // this table maps canonical file into a 'ListenerRegistration' instance - private static HashMap<File, ListenerRegistration> registrations = - new HashMap<>(); - - /** - * 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. - */ - public static 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. - */ - public static Properties getProperties(String fileName) throws IOException - { - return getProperties(new File(fileName)); - } - - /* ============================================================ */ - - /** - * This is the callback interface, used for sending notifications of - * changes in the properties file. - */ - @FunctionalInterface - 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 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<>(); - - // 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() - { - @Override - 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.isEmpty()) - { - 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<>(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.isEmpty()) - { - // 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<>(changedProperties); - - // Do the notification in a separate thread, so blocking - // won't cause any problems. - new Thread() - { - @Override - 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. - */ - public static 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 tempFile = 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(tempFile); - if (reg == null) - { - // a new registration is needed - reg = new ListenerRegistration(tempFile); - } - 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. - */ - public static 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 - * @throws IOException - */ - public static void stopListening(File file, Listener listener) throws IOException - { - if (listener != null) - { - ListenerRegistration reg = registrations.get(file.getCanonicalFile()); - 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 - * @throws IOException - */ - public static void stopListening(String fileName, Listener listener) throws IOException - { - stopListening(new File(fileName), listener); - } - -} +public class PropertyUtil { + + // timer thread used for polling for property file changes + private static Timer timer = null; + + // this table maps canonical file into a 'ListenerRegistration' instance + private static HashMap<File, ListenerRegistration> registrations = new HashMap<>(); + + /** + * 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. + */ + public static 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. + */ + public static Properties getProperties(String fileName) throws IOException { + return getProperties(new File(fileName)); + } + + /* ============================================================ */ + + /** + * This is the callback interface, used for sending notifications of changes in the properties + * file. + */ + @FunctionalInterface + public interface Listener { + /** + * Notification of a properties file change. + * + * @param properties the new properties + * @param changedKeys the set of property names that have changed, including additions and + * removals + */ + void propertiesChanged(Properties properties, Set<String> changedKeys); + } + + /** + * 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<>(); + + // 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() { + @Override + 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.isEmpty()) { + 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<>(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.isEmpty()) { + // 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<>(changedProperties); + + // Do the notification in a separate thread, so blocking + // won't cause any problems. + new Thread() { + @Override + 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 listener 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. + */ + public static 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 tempFile = 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(tempFile); + if (reg == null) { + // a new registration is needed + reg = new ListenerRegistration(tempFile); + } + 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 listener 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. + */ + public static Properties getProperties(String fileName, Listener listener) throws IOException { + return getProperties(new File(fileName), listener); + } + + /** + * Stop listenening for updates. + * + * @param file the properties file + * @param listener notify if not null, this is a callback interface that was used for + * notifications of changes + * @throws IOException If an I/O error occurs + */ + public static void stopListening(File file, Listener listener) throws IOException { + if (listener != null) { + ListenerRegistration reg = registrations.get(file.getCanonicalFile()); + if (reg != null) { + reg.removeListener(listener); + } + } + } + + /** + * Stop listenening for updates. + * + * @param fileName the properties file + * @param listener notify if not null, this is a callback interface that was used for + * notifications of changes + * @throws IOException If an I/O error occurs + */ + public static void stopListening(String fileName, Listener listener) throws IOException { + stopListening(new File(fileName), listener); + } + +} |