/*******************************************************************************
* This file is part of OpenNMS(R).
*
* Copyright (C) 2007-2011 The OpenNMS Group, Inc.
* OpenNMS(R) is Copyright (C) 1999-2011 The OpenNMS Group, Inc.
*
* OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.
*
* OpenNMS(R) is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published
* by the Free Software Foundation, either version 3 of the License,
* or (at your option) any later version.
*
* OpenNMS(R) is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with OpenNMS(R). If not, see:
* http://www.gnu.org/licenses/
*
* For more information contact:
* OpenNMS(R) Licensing <license@opennms.org>
* http://www.opennms.org/
* http://www.opennms.com/
*******************************************************************************/
package org.opennms.core.utils;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Map;
import java.util.Properties;
import java.util.TreeMap;
import java.util.Map.Entry;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* Caches properties files in order to improve performance.
*
* @author <a href="mailto:brozow@opennms.org">Mathew Brozowski</a>
* @version $Id: $
*/
public class PropertiesCache {
private static class PropertiesHolder {
private Properties m_properties;
private final File m_file;
private final Lock lock = new ReentrantLock();
PropertiesHolder(File file) {
m_file = file;
m_properties = null;
}
private Properties read() throws IOException {
if (!m_file.canRead()) {
return null;
}
InputStream in = null;
try {
in = new FileInputStream(m_file);
Properties prop = new Properties();
prop.load(in);
return prop;
} finally {
if (in != null) {
try { in.close(); } catch (IOException e) { }
}
}
}
private void write() throws IOException {
m_file.getParentFile().mkdirs();
OutputStream out = null;
try {
out = new FileOutputStream(m_file);
m_properties.store(out, null);
} finally {
if (out != null) {
try { out.close(); } catch(IOException e) {}
}
}
}
public Properties get() throws IOException {
lock.lock();
try {
if (m_properties == null) {
readWithDefault(new Properties());
}
return m_properties;
} finally {
lock.unlock();
}
}
private void readWithDefault(Properties deflt) throws IOException {
// this is
if (deflt == null && !m_file.canRead()) {
// nothing to load so m_properties remains null no writing necessary
// just return to avoid getting the write lock
return;
}
if (m_properties == null) {
m_properties = read();
if (m_properties == null) {
m_properties = deflt;
}
}
}
public void put(Properties properties) throws IOException {
lock.lock();
try {
m_properties = properties;
write();
} finally {
lock.unlock();
}
}
public void update(Map<String, String> props) throws IOException {
lock.lock();
try {
boolean save = false;
for(Entry<String, String> e : props.entrySet()) {
if (!e.getValue().equals(get().get(e.getKey()))) {
get().put(e.getKey(), e.getValue());
save = true;
}
}
if (save) {
write();
}
} finally {
lock.unlock();
}
}
public void setProperty(String key, String value) throws IOException {
lock.lock();
try {
// first we do get to make sure the properties are loaded
get();
if (!value.equals(get().get(key))) {
get().put(key, value);
write();
}
} finally {
lock.unlock();
}
}
public Properties find() throws IOException {
lock.lock();
try {
if (m_properties == null) {
readWithDefault(null);
}
return m_properties;
} finally {
lock.unlock();
}
}
public String getProperty(String key) throws IOException {
lock.lock();
try {
return get().getProperty(key);
} finally {
lock.unlock();
}
}
}
Map<String, PropertiesHolder> m_cache = new TreeMap<String, PropertiesHolder>();
private PropertiesHolder getHolder(File propFile) throws IOException {
String key = propFile.getCanonicalPath();
synchronized (m_cache) {
PropertiesHolder holder = m_cache.get(key);
if (holder == null) {
holder = new PropertiesHolder(propFile);
m_cache.put(key, holder);
}
return holder;
}
}
/**
* <p>clear</p>
*/
public void clear() {
synchronized (m_cache) {
m_cache.clear();
}
}
/**
* Get the current properties object from the cache loading it in memory
*
* @param propFile a {@link java.io.File} object.
* @throws java.io.IOException if any.
* @return a {@link java.util.Properties} object.
*/
public Properties getProperties(File propFile) throws IOException {
return getHolder(propFile).get();
}
/**
* <p>findProperties</p>
*
* @param propFile a {@link java.io.File} object.
* @return a {@link java.util.Properties} object.
* @throws java.io.IOException if any.
*/
public Properties findProperties(File propFile) throws IOException {
return getHolder(propFile).find();
}
/**
* <p>saveProperties</p>
*
* @param propFile a {@link java.io.File} object.
* @param properties a {@link java.util.Properties} object.
* @throws java.io.IOException if any.
*/
public void saveProperties(File propFile, Properties properties) throws IOException {
getHolder(propFile).put(properties);
}
/**
* <p>updateProperties</p>
*
* @param propFile a {@link java.io.File} object.
* @param props a {@link java.util.Map} object.
* @throws java.io.IOException if any.
*/
public void updateProperties(File propFile, Map<String, String> props) throws IOException {
getHolder(propFile).update(props);
}
/**
* <p>setProperty</p>
*
* @param propFile a {@link java.io.File} object.
* @param key a {@link java.lang.String} object.
* @param value a {@link java.lang.String} object.
* @throws java.io.IOException if any.
*/
public void setProperty(File propFile, String key, String value) throws IOException {
getHolder(propFile).setProperty(key, value);
}
/**
* <p>getProperty</p>
*
* @param propFile a {@link java.io.File} object.
* @param key a {@link java.lang.String} object.
* @return a {@link java.lang.String} object.
* @throws java.io.IOException if any.
*/
public String getProperty(File propFile, String key) throws IOException {
return getHolder(propFile).getProperty(key);
}
}