/*
* Copyright 2010 Lincoln Baxter, III
*
* 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 com.ocpsoft.pretty.faces.config.reload;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import javax.servlet.ServletContext;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.ocpsoft.common.services.ServiceLoader;
import com.ocpsoft.pretty.faces.config.PrettyConfigurator;
import com.ocpsoft.pretty.faces.spi.DevelopmentModeDetector;
/**
* This class reloads the PrettyFaces configuration if PrettyFaces runs in development mode.
*
* @author Christian Kaltepoth
*/
public class PrettyConfigReloader
{
private final Log log = LogFactory.getLog(this.getClass());
/**
* The configuration is reloaded after this amount of time
*/
private final static long CONFIG_RELOAD_DELAY = 2000l;
/**
* Keeps track of the last time the configuration was updated
*/
private long lastUpdate = 0;
/**
* The development mode will be lazily detected
*/
private Boolean developmentMode = null;
public void reloadIfNecessary(ServletContext servletContext)
{
// the development mode detection is started when the first request is received
if (developmentMode == null) {
developmentMode = isDevelopmentModeActive(servletContext);
if (log.isDebugEnabled()) {
if (developmentMode) {
log.debug("PrettyFaces development mode detected! Configuration reloading will be enabled.");
}
else {
log.debug("No development mode detected. Configuration reloading gets disabled.");
}
}
}
// reloading is only done if in development mode
if (developmentMode != null && developmentMode.booleanValue()) {
// the point in time the configuration will be reloaded
long nextUpdate = lastUpdate + CONFIG_RELOAD_DELAY;
if (System.currentTimeMillis() > nextUpdate)
{
if (log.isDebugEnabled()) {
log.debug("Reloading PrettyFaces configuration...");
}
/*
* first update the 'lastUpdate' so that concurrent requests won't
* also do an update of the configuration.
*/
lastUpdate = System.currentTimeMillis();
// run the configuration procedure again
PrettyConfigurator configurator = new PrettyConfigurator(servletContext);
configurator.configure();
}
}
}
/**
* Detects the PrettyFaces development mode using the {@link DevelopmentModeDetector} SPI.
*/
private boolean isDevelopmentModeActive(ServletContext servletContext)
{
// create the ServiceLoader for the SPI
ServiceLoader<DevelopmentModeDetector> serviceLoader = ServiceLoader.load(DevelopmentModeDetector.class);
// we need a list to be able to sort it
List<DevelopmentModeDetector> detectors = new ArrayList<DevelopmentModeDetector>();
for (DevelopmentModeDetector detector : serviceLoader) {
detectors.add(detector);
}
// sort them by priority
Collections.sort(detectors, new Comparator<DevelopmentModeDetector>() {
public int compare(DevelopmentModeDetector left, DevelopmentModeDetector right)
{
return left.getPriority() - right.getPriority();
}
});
// process the detectors until one returns a result != null
for (DevelopmentModeDetector detector : detectors) {
Boolean result = detector.isDevelopmentMode(servletContext);
if (log.isDebugEnabled()) {
log.debug("Detector " + detector.getClass().getSimpleName() + " returned: " + result);
}
if (result != null) {
return result.booleanValue();
}
}
// default value
return false;
}
}