/* Copyright (c) 2001 - 2008 TOPP - www.openplans.org. All rights reserved.
* This code is licensed under the GPL 2.0 license, available at the root
* application directory.
*/
package org.geoserver.flow;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.geoserver.flow.config.DefaultControlFlowConfigurator;
import org.geoserver.ows.HttpErrorCodeException;
import org.geoserver.ows.Request;
import org.geoserver.platform.GeoServerExtensions;
import org.geoserver.platform.Operation;
import org.geotools.util.logging.Logging;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
/**
* Callback that controls the flow of OWS requests based on user specified rules and makes sure
* GeoServer does not get overwhelmed by too many concurrent ones. Can also be used to provide
* different quality of service on different users.
*
* @author Andrea Aime - OpenGeo
*/
public class ControlFlowCallback extends AbstractDispatcherCallback implements
ApplicationContextAware {
static final Logger LOGGER = Logging.getLogger(ControlFlowCallback.class);
static ThreadLocal<List<FlowController>> REQUEST_CONTROLLERS = new ThreadLocal<List<FlowController>>();
static NestedRequestSentinel SENTINEL = new NestedRequestSentinel();
List<FlowController> controllers = Collections.emptyList();
long timeout = -1;
ControlFlowConfigurator configurator;
public void finished(Request request) {
if(SENTINEL.isOutermostRequest()) {
// call back the same controllers we used when the operation started
if (REQUEST_CONTROLLERS.get() != null) {
List<FlowController> fcl = REQUEST_CONTROLLERS.get();
for (FlowController flowController : fcl) {
flowController.requestComplete(request);
}
}
// clean up the thread local
REQUEST_CONTROLLERS.remove();
}
SENTINEL.stop();
}
public Operation operationDispatched(Request request, Operation operation) {
// check if we need to rebuild the flow controller list
if (configurator.isStale())
reloadConfiguration();
// tell the recursion sentinel we're starting a request
SENTINEL.start();
if(SENTINEL.isOutermostRequest()) {
// scan through the existing controllers and set the list in a thread local
// so that this request will get exactly the same list when the operation finishes
List<FlowController> controllers = this.controllers;
if (controllers.size() > 0) {
REQUEST_CONTROLLERS.set(controllers);
long maxTime = timeout > 0 ? System.currentTimeMillis() + timeout : -1;
for (FlowController flowController : controllers) {
if(timeout > 0) {
long maxWait = maxTime - System.currentTimeMillis();
if(!flowController.requestIncoming(request, maxWait))
throw new HttpErrorCodeException(503, "Requested timeout out while waiting to be executed");
} else {
flowController.requestIncoming(request, -1);
}
}
}
}
return operation;
}
/**
* Reloads the flow controller list and replaces the existing ones
*/
void reloadConfiguration() {
try {
List<FlowController> newControllers = new ArrayList<FlowController>(configurator
.buildFlowControllers());
Collections.sort(newControllers, new ControllerPriorityComparator());
controllers = newControllers;
timeout = configurator.getTimeout();
} catch (Exception e) {
LOGGER.log(Level.SEVERE, "Error occurerd during flow controllers reconfiguration");
}
}
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
// look for a ControlFlowConfigurator in the application context, if none is found, use the
// default one
configurator = GeoServerExtensions.bean(ControlFlowConfigurator.class, applicationContext);
if (configurator == null)
configurator = new DefaultControlFlowConfigurator();
}
}