java - 对 servlet 请求调用 startAsync() 会在由 Jetty 9 的 ProxyServlet 终止的过滤器链中抛出 IllegalStateException

Question

环境:

• 在我的环境中，Kibana 4.5.2 在“反向代理 servlet”后面运行，该“反向代理 servlet”是通过扩展 Jetty 的“ProxyServlet”类创建的。
• 这样做是为了可以使用 URL https://Jetty_Server_IP:8443/visual-analytics/proxy/ 访问 Kibana Web 界面...对此 URL 的请求被 Jetty 服务器中运行的反向代理拦截并重定向到 https://localhost:5601/ ...即，到与 Jetty 服务器在同一台机器上运行的 Kibana 服务器。
• 然后，Kibana 服务器处理 Jetty 服务器转发的请求，并将响应返回给网络浏览器。
• 注意: Jetty 在我的应用程序中以“嵌入模式”运行。

问题:

“反向代理 servlet”映射到 URL“/visual-analytics/proxy/*”。

还有另一个“过滤器”映射到 URL“/visual-analytics/proxy/elasticsearch/.kibana/search/*”，其中使用了 ContinuationListener，如以下代码片段所示:

    ContinuationSupport.getContinuation(myRequestWrapper).addContinuationListener(new ContinuationListener() {

                        @Override
                        public void onTimeout(Continuation continuation) {
                            logger.log(Level.WARNING, "Request timeout...");
                        }

                        @Override
                        public void onComplete(Continuation continuation) {

                            HttpServletResponse httpResponse = (HttpServletResponse)continuation.getServletResponse();
                            if (httpResponse.getStatus() == HttpServletResponse.SC_OK || httpResponse.getStatus() == HttpServletResponse.SC_CREATED ) {
                                   //some business logic
                            }

                        }
                    });

    chain.doFilter(myRequestWrapper, response);

上面的 ContinuationListener 在 Jetty 版本 8.1.15.v20140411 上运行良好，并且正在调用监听器的 onComplete() 方法。但是将 Jetty 版本升级到 9.3.14.v20161028 后，ContinuationListener 不再工作，即监听器的 onComplete() 方法和 onTimeout() 方法都不会被调用。

由于 ContinuationListener 不再工作，我将其替换为“javax.servlet.AsyncListener”实现，如以下代码片段所示:

                AsyncContext asyncContext = myRequestWrapper.startAsync();
                asyncContext.addListener(new AsyncListener() {

                    @Override
                    public void onTimeout(AsyncEvent event) throws IOException 
                    {
                                logger.log(Level.WARNING, "Async timeout...");
                    }

                    @Override
                    public void onStartAsync(AsyncEvent event) throws IOException 
                    {
                                logger.log(Level.INFO, "Async start...");
                    }

                    @Override
                    public void onError(AsyncEvent event) throws IOException 
                    {
                                logger.log(Level.SEVERE, "Async error...");
                    }

                    @Override
                    public void onComplete(AsyncEvent event) throws IOException 
                    {
                          HttpServletResponse httpResponse = (HttpServletResponse) event.getSuppliedResponse();
                         //HttpServletResponse httpResponse = (HttpServletResponse) event.getAsyncContext().getResponse();
                        if (httpResponse.getStatus() == HttpServletResponse.SC_OK || httpResponse.getStatus() == HttpServletResponse.SC_CREATED ) {
                                    //some business logic
                        }
                    }
        }, myRequestWrapper, httpServletResponse);

        chain.doFilter(myRequestWrapper, response);

但是添加上述“AsyncListener”实现会导致以下“IllegalStateException”:

   https://164.99.175.139:8443/visual-analytics/proxy/elasticsearch/.kibana/search/test1?op_type=create
    java.lang.IllegalStateException: s=DISPATCHED i=true a=STARTED
            at org.eclipse.jetty.server.HttpChannelState.startAsync(HttpChannelState.java:264)
            at org.eclipse.jetty.server.Request.startAsync(Request.java:2235)
            at javax.servlet.ServletRequestWrapper.startAsync(ServletRequestWrapper.java:432)
            at javax.servlet.ServletRequestWrapper.startAsync(ServletRequestWrapper.java:432)
            at javax.servlet.ServletRequestWrapper.startAsync(ServletRequestWrapper.java:432)
            at org.eclipse.jetty.proxy.ProxyServlet.service(ProxyServlet.java:88)
            at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
            at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:845)
            at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1712)
            at com.netiq.sentinel.kibana.search.KibanaSearchFilter.doFilter(KibanaSearchFilter.java:249)
            at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1699)
            at com.netiq.sentinel.kibana.proxy.AcceptEncodingHeaderModificationFilter.doFilter(AcceptEncodingHeaderModificationFilter.java:37)
            at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1699)
            at com.netiq.sentinel.kibana.proxy.SecurityFilter.doFilter(SecurityFilter.java:41)
            at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1699)
            at com.netiq.sentinel.kibana.proxy.AuditFilter.doFilter(AuditFilter.java:104)
            at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1699)
            at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:582)
            at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
            at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548)
            at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:226)
            at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1180)
            at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:512)
            at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
            at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1112)
            at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
            at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:213)
            at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:119)
            at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:134)
            at org.eclipse.jetty.server.Server.handle(Server.java:534)
            at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:320)
            at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251)
            at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:273)
            at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:95)
            at org.eclipse.jetty.io.ssl.SslConnection.onFillable(SslConnection.java:202)
            at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:273)
            at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:95)
            at org.eclipse.jetty.io.SelectChannelEndPoint$2.run(SelectChannelEndPoint.java:93)
            at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.executeProduceConsume(ExecuteProduceConsume.java:303)
            at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.produceConsume(ExecuteProduceConsume.java:148)
            at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.run(ExecuteProduceConsume.java:136)
            at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:671)
            at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:589)
            at java.lang.Thread.run(Thread.java:745)

上述堆栈跟踪中提到的“ProxyServlet.java”中的第 88 行具有以下代码:

final AsyncContext asyncContext = request.startAsync();

是否会抛出“IllegalStateException”，因为在同一个请求上两次调用 startAsync() 方法 - 第一次在我的过滤器中，第二次在 Jetty ProxyServlet 的 service() 方法中？如果是，是否无法在由 Jetty 的 ProxyServlet 终止的过滤器链中使用“AsyncListener”？

任何有关如何进一步进行的指示将不胜感激。期待任何回应...

Answer 1

仅供引用，我按如下方式修复了此问题:

1. 我没有使用 Jetty 的“ContinuationListener”，而是使用了 Servlet 3.0 的“AsyncListener”，因为升级到 Jetty 9.3.14.v20161028 后，Jetty 的“ContinuationListener”似乎不起作用。这可能是 Jetty 的错误。
2. 监听器相关的代码段位于过滤器的“chain.doFilter()”调用之前。我将此代码段移动到过滤器的“chain.doFilter()”调用之后的位置，以便我可以检索在 Jetty ProxyServlet 的 service() 方法中“已创建”的 AsyncContext。然后我可以将 AsyncListener 添加到检索到的 AsyncContext 中。
3. 我将过滤器中的“request.startAsync()”调用更改为“request.getAsyncContext()”，这样我就不会启动一个导致 IllegalStateException 的新 AsyncContext，而只检索已在中创建的 AsyncContext Jetty 的 ProxyServlet。

所以更新后的代码段如下所示:

            chain.doFilter(myRequestWrapper, response);

            AsyncContext asyncContext = myRequestWrapper.getAsyncContext();
            asyncContext.addListener(new AsyncListener() {

                @Override
                public void onTimeout(AsyncEvent event) throws IOException 
                {
                            logger.log(Level.WARNING, "Async timeout...");
                }

                @Override
                public void onStartAsync(AsyncEvent event) throws IOException 
                {
                            logger.log(Level.INFO, "Async start...");
                }

                @Override
                public void onError(AsyncEvent event) throws IOException 
                {
                            logger.log(Level.SEVERE, "Async error...");
                }

                @Override
                public void onComplete(AsyncEvent event) throws IOException 
                {
                      HttpServletResponse httpResponse = (HttpServletResponse) event.getSuppliedResponse();
                     //HttpServletResponse httpResponse = (HttpServletResponse) event.getAsyncContext().getResponse();
                    if (httpResponse.getStatus() == HttpServletResponse.SC_OK || httpResponse.getStatus() == HttpServletResponse.SC_CREATED ) {
                                //some business logic
                    }
                }
    }, myRequestWrapper, httpServletResponse);