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/*
 * Copyright 2006 Google Inc.
 * 
 * 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.mortbay.gwt;

import com.google.gwt.user.server.rpc.OpenRemoteServiceServlet;
import com.google.gwt.user.server.rpc.UnexpectedException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.ServletException;
import java.io.IOException;

/**
 * Jetty Continuation support for GWT RPC.
 * 
 * @author Craig Day ([email protected])
 */
public class AsyncRemoteServiceServlet extends OpenRemoteServiceServlet {

    public static final String PAYLOAD = "com.google.gwt.payload";

    private static final String JETTY_RETRY_REQUEST_EXCEPTION = "org.mortbay.jetty.RetryRequest";

    /* ------------------------------------------------------------ */
    /* (non-Javadoc)
     * @see com.google.gwt.user.server.rpc.OpenRemoteServiceServlet#readPayloadAsUtf8(javax.servlet.http.HttpServletRequest)
     */
    protected String readPayloadAsUtf8(HttpServletRequest request) throws IOException, ServletException {
        String payload = (String) request.getAttribute(PAYLOAD);
        if (payload == null) {
            payload = super.readPayloadAsUtf8(request);
            request.setAttribute(PAYLOAD, payload);
        }
        return payload;
    }


    /**
     * Overridden to really throw Jetty RetryRequest Exception (as opposed to sending failure to client).
     *
     * @param caught the exception
     */
    protected void doUnexpectedFailure(Throwable caught) {
        throwIfRetryRequest(caught);
        super.doUnexpectedFailure(caught);
    }

    /**
     * Throws the Jetty RetryRequest if found.
     *
     * @param caught the exception
     */
    protected void throwIfRetryRequest(Throwable caught) {
        if (caught instanceof UnexpectedException) {
            caught = caught.getCause();
        }
        if (caught instanceof ThreadDeath && JETTY_RETRY_REQUEST_EXCEPTION.equals(caught.getClass().getName())) {
            throw (Error) caught;
        }
    }


}