/*
* COMSAT
* Copyright (c) 2013-2014, Parallel Universe Software Co. All rights reserved.
*
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
*
* or (per the licensee's choosing)
*
* under the terms of the GNU Lesser General Public License version 3.0
* as published by the Free Software Foundation.
*/
package co.paralleluniverse.fibers.servlet;
import co.paralleluniverse.fibers.Fiber;
import co.paralleluniverse.fibers.SuspendExecution;
import co.paralleluniverse.strands.SuspendableRunnable;
import java.io.IOException;
import javax.servlet.AsyncContext;
import javax.servlet.GenericServlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
/**
* Implements a {@link GenericServlet} that services requests using a fiber-per-request model.
*/
public abstract class FiberGenericServlet extends GenericServlet {
private static final long serialVersionUID = 1L;
private transient FiberServletConfig configAD;
private transient FiberServletContext contextAD;
private final ThreadLocal<AsyncContext> currentAsyncContext = new ThreadLocal<AsyncContext>();
/**
*
* @return Wrapped version of the ServletConfig initiated by {@link #init(javax.servlet.ServletConfig) }
*/
@Override
public final ServletConfig getServletConfig() {
return configAD;
}
/**
* @inheritDoc
*
* @return Wrapped version of the ServletContext initiated by {@link #init(javax.servlet.ServletConfig) }
*/
@Override
public ServletContext getServletContext() {
return contextAD;
}
@Override
public void init(ServletConfig config) throws ServletException {
this.contextAD = new FiberServletContext(config.getServletContext(), currentAsyncContext);
this.configAD = new FiberServletConfig(config, contextAD);
this.init();
}
/**
* @inheritDoc
*
* Called by the servlet container to allow the servlet to respond to a request.
* This implementation puts the servlet in async mode and then spawns a fiber that calls
* {@link #suspendableService} to service the request.
*/
@Override
public final void service(final ServletRequest req, final ServletResponse res) {
req.setAttribute("org.apache.catalina.ASYNC_SUPPORTED", true);
final AsyncContext ac = req.startAsync();
final FiberServletRequest srad = wrapRequest(req);
new Fiber(new SuspendableRunnable() {
@Override
public void run() throws SuspendExecution, InterruptedException {
try {
currentAsyncContext.set(ac);
suspendableService(srad, res);
} catch (Exception ex) {
log("Exception in fiber servlet", ex);
} finally {
if (req.isAsyncStarted())
ac.complete();
currentAsyncContext.set(null);
}
}
}).start();
}
/**
* Called by the servlet container to allow the servlet to respond to a request. See {@link javax.servlet.Servlet#service}.
* This methods may call suspendable functions since it runs in fiber context.
*
* <p>This method is declared abstract so subclasses, such as {@code FiberHttpServlet}, must override it.
*
* @param req the {@code ServletRequest} object that contains the client's request
* @param res the {@code ServletResponse} object that will contain the servlet's response
*
* @exception ServletException if an exception occurs that interferes with the servlet's normal operation occurred
* @exception IOException if an input or output exception occurs
*/
protected abstract void suspendableService(ServletRequest req, ServletResponse res)
throws ServletException, IOException, SuspendExecution;
FiberServletRequest wrapRequest(final ServletRequest req) {
return new FiberServletRequest(req);
}
}