Tomcat源码---请求处理四(1)

 

 一,现在到了StandardWrapperValve#invoke下,现在才算是真正的调用,主要实现了对servlet,filter执行

 

/**
     * Invoke the servlet we are managing, respecting the rules regarding
     * servlet lifecycle and SingleThreadModel support.
     *
     * @param request Request to be processed
     * @param response Response to be produced
     * @param valveContext Valve context used to forward to the next Valve
     *
     * @exception IOException if an input/output error occurred
     * @exception ServletException if a servlet error occurred
     */
    public final void invoke(Request request, Response response)
        throws IOException, ServletException {

        // Initialize local variables we may need
        boolean unavailable = false;
        Throwable throwable = null;
        // This should be a Request attribute...
        long t1=System.currentTimeMillis();
        requestCount++;
        StandardWrapper wrapper = (StandardWrapper) getContainer();
        Servlet servlet = null;
        Context context = (Context) wrapper.getParent();
        
        // Check for the application being marked unavailable
        if (!context.getAvailable()) {
        	response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,
                           sm.getString("standardContext.isUnavailable"));
            unavailable = true;
        }

        // Check for the servlet being marked unavailable
        if (!unavailable && wrapper.isUnavailable()) {
            container.getLogger().info(sm.getString("standardWrapper.isUnavailable",
                    wrapper.getName()));
            long available = wrapper.getAvailable();
            if ((available > 0L) && (available < Long.MAX_VALUE)) {
                response.setDateHeader("Retry-After", available);
                response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,
                        sm.getString("standardWrapper.isUnavailable",
                                wrapper.getName()));
            } else if (available == Long.MAX_VALUE) {
                response.sendError(HttpServletResponse.SC_NOT_FOUND,
                        sm.getString("standardWrapper.notFound",
                                wrapper.getName()));
            }
            unavailable = true;
        }

        // Allocate a servlet instance to process this request
        try {
            if (!unavailable) {
                //servlet行行在这一步
                servlet = wrapper.allocate();
            }
        } catch (UnavailableException e) {
            container.getLogger().error(
                    sm.getString("standardWrapper.allocateException",
                            wrapper.getName()), e);
            long available = wrapper.getAvailable();
            if ((available > 0L) && (available < Long.MAX_VALUE)) {
            	response.setDateHeader("Retry-After", available);
            	response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,
                           sm.getString("standardWrapper.isUnavailable",
                                        wrapper.getName()));
            } else if (available == Long.MAX_VALUE) {
            	response.sendError(HttpServletResponse.SC_NOT_FOUND,
                           sm.getString("standardWrapper.notFound",
                                        wrapper.getName()));
            }
        } catch (ServletException e) {
            container.getLogger().error(sm.getString("standardWrapper.allocateException",
                             wrapper.getName()), StandardWrapper.getRootCause(e));
            throwable = e;
            exception(request, response, e);
            servlet = null;
        } catch (Throwable e) {
            container.getLogger().error(sm.getString("standardWrapper.allocateException",
                             wrapper.getName()), e);
            throwable = e;
            exception(request, response, e);
            servlet = null;
        }

        // Identify if the request is Comet related now that the servlet has been allocated
        boolean comet = false;
        if (servlet instanceof CometProcessor 
                && request.getAttribute("org.apache.tomcat.comet.support") == Boolean.TRUE) {
            comet = true;
            request.setComet(true);
        }
        
        // Acknowledge the request
        try {
             //通知request已经调用
            response.sendAcknowledgement();
        } catch (IOException e) {
        	request.removeAttribute(Globals.JSP_FILE_ATTR);
            container.getLogger().warn(sm.getString("standardWrapper.acknowledgeException",
                             wrapper.getName()), e);
            throwable = e;
            exception(request, response, e);
        } catch (Throwable e) {
            container.getLogger().error(sm.getString("standardWrapper.acknowledgeException",
                             wrapper.getName()), e);
            throwable = e;
            exception(request, response, e);
            servlet = null;
        }
        MessageBytes requestPathMB = null;
        if (request != null) {
            requestPathMB = request.getRequestPathMB();
        }
        request.setAttribute
            (ApplicationFilterFactory.DISPATCHER_TYPE_ATTR,
             ApplicationFilterFactory.REQUEST_INTEGER);
        request.setAttribute
            (ApplicationFilterFactory.DISPATCHER_REQUEST_PATH_ATTR,
             requestPathMB);
        // Create the filter chain for this request
        ApplicationFilterFactory factory =
            ApplicationFilterFactory.getInstance();
        //过滤链的创建
        ApplicationFilterChain filterChain =
            factory.createFilterChain(request, wrapper, servlet);
        // Reset comet flag value after creating the filter chain
        request.setComet(false);

        // Call the filter chain for this request
        // NOTE: This also calls the servlet's service() method
        try {
            String jspFile = wrapper.getJspFile();
            if (jspFile != null)
            	request.setAttribute(Globals.JSP_FILE_ATTR, jspFile);
            else
            	request.removeAttribute(Globals.JSP_FILE_ATTR);
            if ((servlet != null) && (filterChain != null)) {
                // Swallow output if needed
                if (context.getSwallowOutput()) {
                    try {
                        SystemLogHandler.startCapture();
                        if (comet) {
                            filterChain.doFilterEvent(request.getEvent());
                            request.setComet(true);
                        } else {
                            //这里面开始对过滤器进行处理
                            filterChain.doFilter(request.getRequest(), 
                                    response.getResponse());
                        }
                    } finally {
                        String log = SystemLogHandler.stopCapture();
                        if (log != null && log.length() > 0) {
                            context.getLogger().info(log);
                        }
                    }
                } else {
                    if (comet) {
                        request.setComet(true);
                        filterChain.doFilterEvent(request.getEvent());
                    } else {
                        filterChain.doFilter
                            (request.getRequest(), response.getResponse());
                    }
                }

            }
            request.removeAttribute(Globals.JSP_FILE_ATTR);
        } catch (ClientAbortException e) {
        	request.removeAttribute(Globals.JSP_FILE_ATTR);
            throwable = e;
            exception(request, response, e);
        } catch (IOException e) {
        	request.removeAttribute(Globals.JSP_FILE_ATTR);
            container.getLogger().error(sm.getString("standardWrapper.serviceException",
                             wrapper.getName()), e);
            throwable = e;
            exception(request, response, e);
        } catch (UnavailableException e) {
        	request.removeAttribute(Globals.JSP_FILE_ATTR);
            container.getLogger().error(sm.getString("standardWrapper.serviceException",
                             wrapper.getName()), e);
            //            throwable = e;
            //            exception(request, response, e);
            wrapper.unavailable(e);
            long available = wrapper.getAvailable();
            if ((available > 0L) && (available < Long.MAX_VALUE)) {
                response.setDateHeader("Retry-After", available);
                response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,
                           sm.getString("standardWrapper.isUnavailable",
                                        wrapper.getName()));
            } else if (available == Long.MAX_VALUE) {
            	response.sendError(HttpServletResponse.SC_NOT_FOUND,
                            sm.getString("standardWrapper.notFound",
                                        wrapper.getName()));
            }
            // Do not save exception in 'throwable', because we
            // do not want to do exception(request, response, e) processing
        } catch (ServletException e) {
        	request.removeAttribute(Globals.JSP_FILE_ATTR);
            Throwable rootCause = StandardWrapper.getRootCause(e);
            if (!(rootCause instanceof ClientAbortException)) {
                container.getLogger().error(sm.getString("standardWrapper.serviceException",
                                 wrapper.getName()), rootCause);
            }
            throwable = e;
            exception(request, response, e);
        } catch (Throwable e) {
            request.removeAttribute(Globals.JSP_FILE_ATTR);
            container.getLogger().error(sm.getString("standardWrapper.serviceException",
                             wrapper.getName()), e);
            throwable = e;
            exception(request, response, e);
        }

        // Release the filter chain (if any) for this request
        if (filterChain != null) {
            if (request.isComet()) {
                // If this is a Comet request, then the same chain will be used for the
                // processing of all subsequent events.
                filterChain.reuse();
            } else {
                filterChain.release();
            }
        }

        // Deallocate the allocated servlet instance
        try {
            if (servlet != null) {
               //servlet释放
                wrapper.deallocate(servlet);
            }
        } catch (Throwable e) {
            container.getLogger().error(sm.getString("standardWrapper.deallocateException",
                             wrapper.getName()), e);
            if (throwable == null) {
                throwable = e;
                exception(request, response, e);
            }
        }

        // If this servlet has been marked permanently unavailable,
        // unload it and release this instance
        try {
            if ((servlet != null) &&
                (wrapper.getAvailable() == Long.MAX_VALUE)) {
                wrapper.unload();
            }
        } catch (Throwable e) {
            container.getLogger().error(sm.getString("standardWrapper.unloadException",
                             wrapper.getName()), e);
            if (throwable == null) {
                throwable = e;
                exception(request, response, e);
            }
        }
        long t2=System.currentTimeMillis();

        long time=t2-t1;
        processingTime += time;
        if( time > maxTime) maxTime=time;
        if( time < minTime) minTime=time;

    }