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//
// ========================================================================
// Copyright (c) 1995-2012 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.continuation;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
/* ------------------------------------------------------------ */
/**
* <p>ContinuationFilter must be applied to servlet paths that make use of
* the asynchronous features provided by {@link Continuation} APIs, but that
* are deployed in servlet containers that are neither Jetty (>= 7) nor a
* compliant Servlet 3.0 container.</p>
* <p>The following init parameters may be used to configure the filter (these are mostly for testing):</p>
* <dl>
* <dt>debug</dt><dd>Boolean controlling debug output</dd>
* <dt>jetty6</dt><dd>Boolean to force use of Jetty 6 continuations</dd>
* <dt>faux</dt><dd>Boolean to force use of faux continuations</dd>
* </dl>
* <p>If the servlet container is not Jetty (either 6 or 7) nor a Servlet 3
* container, then "faux" continuations will be used.</p>
* <p>Faux continuations will just put the thread that called {@link Continuation#suspend()}
* in wait, and will notify that thread when {@link Continuation#resume()} or
* {@link Continuation#complete()} is called.</p>
* <p>Faux continuations are not threadless continuations (they are "faux" - fake - for this reason)
* and as such they will scale less than proper continuations.</p>
*/
public class ContinuationFilter implements Filter
{
static boolean _initialized;
static boolean __debug; // shared debug status
private boolean _faux;
private boolean _jetty6;
private boolean _filtered;
ServletContext _context;
private boolean _debug;
public void init(FilterConfig filterConfig) throws ServletException
{
boolean jetty_7_or_greater="org.eclipse.jetty.servlet".equals(filterConfig.getClass().getPackage().getName());
_context = filterConfig.getServletContext();
String param=filterConfig.getInitParameter("debug");
_debug=param!=null&&Boolean.parseBoolean(param);
if (_debug)
__debug=true;
param=filterConfig.getInitParameter("jetty6");
if (param==null)
param=filterConfig.getInitParameter("partial");
if (param!=null)
_jetty6=Boolean.parseBoolean(param);
else
_jetty6=ContinuationSupport.__jetty6 && !jetty_7_or_greater;
param=filterConfig.getInitParameter("faux");
if (param!=null)
_faux=Boolean.parseBoolean(param);
else
_faux=!(jetty_7_or_greater || _jetty6 || _context.getMajorVersion()>=3);
_filtered=_faux||_jetty6;
if (_debug)
_context.log("ContinuationFilter "+
" jetty="+jetty_7_or_greater+
" jetty6="+_jetty6+
" faux="+_faux+
" filtered="+_filtered+
" servlet3="+ContinuationSupport.__servlet3);
_initialized=true;
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException
{
if (_filtered)
{
Continuation c = (Continuation) request.getAttribute(Continuation.ATTRIBUTE);
FilteredContinuation fc;
if (_faux && (c==null || !(c instanceof FauxContinuation)))
{
fc = new FauxContinuation(request);
request.setAttribute(Continuation.ATTRIBUTE,fc);
}
else
fc=(FilteredContinuation)c;
boolean complete=false;
while (!complete)
{
try
{
if (fc==null || (fc).enter(response))
chain.doFilter(request,response);
}
catch (ContinuationThrowable e)
{
debug("faux",e);
}
finally
{
if (fc==null)
fc = (FilteredContinuation) request.getAttribute(Continuation.ATTRIBUTE);
complete=fc==null || (fc).exit();
}
}
}
else
{
try
{
chain.doFilter(request,response);
}
catch (ContinuationThrowable e)
{
debug("caught",e);
}
}
}
private void debug(String string)
{
if (_debug)
{
_context.log(string);
}
}
private void debug(String string, Throwable th)
{
if (_debug)
{
if (th instanceof ContinuationThrowable)
_context.log(string+":"+th);
else
_context.log(string,th);
}
}
public void destroy()
{
}
public interface FilteredContinuation extends Continuation
{
boolean enter(ServletResponse response);
boolean exit();
}
}
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