/*
* Copyright 2010-2014 the original author or authors.
*
* 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 org.springframework.boot.actuate.system;
import java.io.File;
import java.io.IOException;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.boot.ApplicationPid;
import org.springframework.boot.bind.RelaxedPropertyResolver;
import org.springframework.boot.context.event.ApplicationEnvironmentPreparedEvent;
import org.springframework.boot.context.event.ApplicationPreparedEvent;
import org.springframework.boot.context.event.SpringApplicationEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.core.Ordered;
import org.springframework.core.env.Environment;
import org.springframework.util.Assert;
/**
* An {@link ApplicationListener} that saves application PID into file. This application
* listener will be triggered exactly once per JVM, and the file name can be overridden at
* runtime with a System property or environment variable named "PIDFILE" (or "pidfile")
* or using a {@code spring.application.pidfile} property in the Spring
* {@link Environment}.
*
* @author Jakub Kubrynski
* @author Dave Syer
* @author Phillip Webb
* @since 1.2.0
*/
public class ApplicationPidFileWriter implements
ApplicationListener<SpringApplicationEvent>, Ordered {
private static final Log logger = LogFactory.getLog(ApplicationPidFileWriter.class);
private static final String DEFAULT_FILE_NAME = "application.pid";
private static final String[] SYSTEM_PROPERTY_VARIABLES = { "PIDFILE", "pidfile" };
private static final String SPRING_PROPERTY = "spring.pidfile";
private static final AtomicBoolean created = new AtomicBoolean(false);
private int order = Ordered.HIGHEST_PRECEDENCE + 13;
private final File file;
private Class<? extends SpringApplicationEvent> triggerEventType = ApplicationPreparedEvent.class;
/**
* Create a new {@link ApplicationPidFileWriter} instance using the filename
* 'application.pid'.
*/
public ApplicationPidFileWriter() {
this(new File(DEFAULT_FILE_NAME));
}
/**
* Create a new {@link ApplicationPidFileWriter} instance with a specified filename.
* @param filename the name of file containing pid
*/
public ApplicationPidFileWriter(String filename) {
this(new File(filename));
}
/**
* Create a new {@link ApplicationPidFileWriter} instance with a specified file.
* @param file the file containing pid
*/
public ApplicationPidFileWriter(File file) {
Assert.notNull(file, "File must not be null");
this.file = file;
}
/**
* Sets the type of application event that will trigger writing of the PID file.
* Defaults to {@link ApplicationPreparedEvent}. NOTE: If you use the
* {@link ApplicationPreparedEvent} to trigger the write, you will not be able to
* specify the PID filename in the Spring {@link Environment}.
*/
public void setTriggerEventType(
Class<? extends SpringApplicationEvent> triggerEventType) {
Assert.notNull(triggerEventType, "Trigger event type must not be null");
this.triggerEventType = triggerEventType;
}
@Override
public void onApplicationEvent(SpringApplicationEvent event) {
if (this.triggerEventType.isInstance(event)) {
if (created.compareAndSet(false, true)) {
try {
writePidFile(event);
}
catch (Exception ex) {
logger.warn(String.format("Cannot create pid file %s", this.file));
}
}
}
}
private void writePidFile(SpringApplicationEvent event) throws IOException {
File pidFile = this.file;
String override = SystemProperties.get(SYSTEM_PROPERTY_VARIABLES);
if (override != null) {
pidFile = new File(override);
}
else {
Environment environment = getEnvironment(event);
if (environment != null) {
override = new RelaxedPropertyResolver(environment)
.getProperty(SPRING_PROPERTY);
if (override != null) {
pidFile = new File(override);
}
}
}
new ApplicationPid().write(pidFile);
pidFile.deleteOnExit();
}
private Environment getEnvironment(SpringApplicationEvent event) {
if (event instanceof ApplicationEnvironmentPreparedEvent) {
return ((ApplicationEnvironmentPreparedEvent) event).getEnvironment();
}
if (event instanceof ApplicationPreparedEvent) {
return ((ApplicationPreparedEvent) event).getApplicationContext()
.getEnvironment();
}
return null;
}
public void setOrder(int order) {
this.order = order;
}
@Override
public int getOrder() {
return this.order;
}
/**
* Reset the created flag for testing purposes.
*/
static void reset() {
created.set(false);
}
}