/**
* 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.falcon.util;
import org.apache.falcon.FalconException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Properties;
import java.util.concurrent.atomic.AtomicReference;
/**
* Dynamic properties that may be modified while the server is running.
*/
public final class RuntimeProperties extends ApplicationProperties {
private static final Logger LOG = LoggerFactory.getLogger(RuntimeProperties.class);
private static final String PROPERTY_FILE = "runtime.properties";
private static final AtomicReference<RuntimeProperties> INSTANCE =
new AtomicReference<RuntimeProperties>();
private RuntimeProperties() throws FalconException {
super();
}
@Override
protected String getPropertyFile() {
return PROPERTY_FILE;
}
public static Properties get() {
try {
if (INSTANCE.get() == null) {
RuntimeProperties properties = new RuntimeProperties();
properties.loadProperties();
properties.validateProperties();
INSTANCE.compareAndSet(null, properties);
if (INSTANCE.get() == properties) {
Thread refreshThread = new Thread(new DynamicLoader());
refreshThread.start();
}
}
return INSTANCE.get();
} catch (FalconException e) {
throw new RuntimeException("Unable to read application " + "runtime properties", e);
}
}
protected void validateProperties() throws FalconException {
String colosProp = getProperty("all.colos");
if (colosProp == null || colosProp.isEmpty()) {
return;
}
String[] colos = colosProp.split(",");
for (int i = 0; i < colos.length; i++) {
colos[i] = colos[i].trim();
String falconEndpoint = getProperty("falcon." + colos[i] + ".endpoint");
if (falconEndpoint == null || falconEndpoint.isEmpty()) {
throw new FalconException("No falcon server endpoint mentioned in Prism runtime for colo, "
+ colos[i] + ".");
}
}
}
/**
* Thread for loading properties periodically.
*/
private static final class DynamicLoader implements Runnable {
private static final long REFRESH_DELAY = 300000L;
private static final int MAX_ITER = 20; //1hr
@Override
public void run() {
long backOffDelay = REFRESH_DELAY;
while (true) {
try {
Thread.sleep(Math.min(MAX_ITER * REFRESH_DELAY, backOffDelay));
try {
RuntimeProperties newProperties = new RuntimeProperties();
newProperties.loadProperties();
newProperties.validateProperties();
INSTANCE.set(newProperties);
backOffDelay = REFRESH_DELAY;
} catch (FalconException e) {
LOG.warn("Error refreshing runtime properties", e);
backOffDelay += REFRESH_DELAY;
}
} catch (InterruptedException e) {
LOG.error("Application is stopping. Aborting...");
break;
}
}
}
}
}