hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/webapp/Dispatcher.java - hadoop - Git at Google

 /**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.hadoop.yarn.webapp;

 import static com.google.common.base.Preconditions.checkState;

 import java.io.IOException;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.Timer;
 import java.util.TimerTask;

 import javax.servlet.ServletException;
 import javax.servlet.http.Cookie;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.http.HtmlQuoting;
 import org.apache.hadoop.yarn.webapp.Controller.RequestContext;
 import org.apache.hadoop.yarn.webapp.Router.Dest;
 import org.apache.hadoop.yarn.webapp.view.ErrorPage;
 import org.apache.hadoop.yarn.webapp.view.RobotsTextPage;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 import com.google.common.collect.Iterables;
 import com.google.inject.Inject;
 import com.google.inject.Injector;
 import com.google.inject.Singleton;

 /**
  * The servlet that dispatch request to various controllers
  * according to the user defined routes in the router.
  */
 @InterfaceAudience.LimitedPrivate({"YARN", "MapReduce"})
 @Singleton
 public class Dispatcher extends HttpServlet {
   private static final long serialVersionUID = 1L;
   static final Logger LOG = LoggerFactory.getLogger(Dispatcher.class);
   static final String ERROR_COOKIE = "last-error";
   static final String STATUS_COOKIE = "last-status";

   private transient final Injector injector;
   private transient final Router router;
   private transient final WebApp webApp;
   private volatile boolean devMode = false;

   @Inject
   Dispatcher(WebApp webApp, Injector injector, Router router) {
     this.webApp = webApp;
     this.injector = injector;
     this.router = router;
   }

   @Override
   public void doOptions(HttpServletRequest req, HttpServletResponse res) {
     // for simplicity
     res.setHeader("Allow", "GET, POST");
   }

   @Override
   public void service(HttpServletRequest req, HttpServletResponse res)
       throws ServletException, IOException {
     res.setCharacterEncoding("UTF-8");
     String uri = HtmlQuoting.quoteHtmlChars(req.getRequestURI());

     if (uri == null) {
       uri = "/";
     }
     if (devMode && uri.equals("/__stop")) {
       // quick hack to restart servers in dev mode without OS commands
       res.setStatus(res.SC_NO_CONTENT);
       LOG.info("dev mode restart requested");
       prepareToExit();
       return;
     }
     // if they provide a redirectPath go there instead of going to
     // "/" so that filters can differentiate the webapps.
     if (uri.equals("/")) {
       String redirectPath = webApp.getRedirectPath();
       if (redirectPath != null && !redirectPath.isEmpty()) {
         res.sendRedirect(redirectPath);
         return;
       }
     }
     String method = req.getMethod();
     if (method.equals("OPTIONS")) {
       doOptions(req, res);
       return;
     }
     if (method.equals("TRACE")) {
       doTrace(req, res);
       return;
     }
     if (method.equals("HEAD")) {
       doGet(req, res); // default to bad request
       return;
     }
     String pathInfo = req.getPathInfo();
     if (pathInfo == null) {
       pathInfo = "/";
     }
     // The implementation class of HttpServletRequest in
     // Guice-3.0 does not decode paths that are encoded,
     // decode path info here for further operation.
     try {
       pathInfo = new URI(pathInfo).getPath();
     }  catch (URISyntaxException ex) {
       // Just leave it alone for compatibility.
       LOG.error(pathInfo + ": Failed to decode path.", ex);
     }
     Controller.RequestContext rc =
         injector.getInstance(Controller.RequestContext.class);

     //short-circuit robots.txt serving for all YARN webapps.
     if (uri.equals(RobotsTextPage.ROBOTS_TXT_PATH)) {
       rc.setStatus(HttpServletResponse.SC_FOUND);
       render(RobotsTextPage.class);
       return;
     }

     if (setCookieParams(rc, req) > 0) {
       Cookie ec = rc.cookies().get(ERROR_COOKIE);
       if (ec != null) {
         rc.setStatus(Integer.parseInt(rc.cookies().
             get(STATUS_COOKIE).getValue()));
         removeErrorCookies(res, uri);
         rc.set(Params.ERROR_DETAILS, ec.getValue());
         render(ErrorPage.class);
         return;
       }
     }
     rc.prefix = webApp.name();
     Router.Dest dest = null;
     try {
       dest = router.resolve(method, pathInfo);
     } catch (WebAppException e) {
       rc.error = e;
       if (!e.getMessage().contains("not found")) {
         rc.setStatus(res.SC_INTERNAL_SERVER_ERROR);
         render(ErrorPage.class);
         return;
       }
     }
     if (dest == null) {
       rc.setStatus(res.SC_NOT_FOUND);
       render(ErrorPage.class);
       return;
     }
     rc.devMode = devMode;
     setMoreParams(rc, pathInfo, dest);
     Controller controller = injector.getInstance(dest.controllerClass);
     try {
       // TODO: support args converted from /path/:arg1/...
       dest.action.invoke(controller, (Object[]) null);
       if (!rc.rendered) {
         if (dest.defaultViewClass != null) {
           render(dest.defaultViewClass);
         } else if (rc.status == 200) {
           throw new IllegalStateException("No view rendered for 200");
         }
       }
     } catch (Exception e) {
       LOG.error("error handling URI: "+ uri, e);
       // Page could be half rendered (but still not flushed). So redirect.
       redirectToErrorPage(res, e, uri, devMode);
     }
   }

   public static void redirectToErrorPage(HttpServletResponse res, Throwable e,
                                          String path, boolean devMode) {
     String st = devMode ? ErrorPage.toStackTrace(e, 1024 * 3) // spec: min 4KB
                         : "See logs for stack trace";
     res.setStatus(res.SC_FOUND);
     Cookie cookie = new Cookie(STATUS_COOKIE, String.valueOf(500));
     cookie.setPath(path);
     res.addCookie(cookie);
     cookie = new Cookie(ERROR_COOKIE, st);
     cookie.setPath(path);
     res.addCookie(cookie);
     res.setHeader("Location", path);
   }

   public static void removeErrorCookies(HttpServletResponse res, String path) {
     removeCookie(res, ERROR_COOKIE, path);
     removeCookie(res, STATUS_COOKIE, path);
   }

   public static void removeCookie(HttpServletResponse res, String name,
                                   String path) {
     LOG.debug("removing cookie {} on {}", name, path);
     Cookie c = new Cookie(name, "");
     c.setMaxAge(0);
     c.setPath(path);
     res.addCookie(c);
   }

   private void render(Class<? extends View> cls) {
     injector.getInstance(cls).render();
   }

   // /path/foo/bar with /path/:arg1/:arg2 will set {arg1=>foo, arg2=>bar}
   private void setMoreParams(RequestContext rc, String pathInfo, Dest dest) {
     checkState(pathInfo.startsWith(dest.prefix), "prefix should match");
     if (dest.pathParams.size() == 0 ||
         dest.prefix.length() == pathInfo.length()) {
       return;
     }
     String[] parts = Iterables.toArray(WebApp.pathSplitter.split(
         pathInfo.substring(dest.prefix.length())), String.class);
     LOG.debug("parts={}, params={}", parts, dest.pathParams);
     for (int i = 0; i < dest.pathParams.size() && i < parts.length; ++i) {
       String key = dest.pathParams.get(i);
       if (key.charAt(0) == ':') {
         rc.moreParams().put(key.substring(1), parts[i]);
       }
     }
   }

   private int setCookieParams(RequestContext rc, HttpServletRequest req) {
     Cookie[] cookies = req.getCookies();
     if (cookies != null) {
       for (Cookie cookie : cookies) {
         rc.cookies().put(cookie.getName(), cookie);
       }
       return cookies.length;
     }
     return 0;
   }

   public void setDevMode(boolean choice) {
     devMode = choice;
   }

   private void prepareToExit() {
     checkState(devMode, "only in dev mode");
     new Timer("webapp exit", true).schedule(new TimerTask() {
       @Override public void run() {
         LOG.info("WebAppp /{} exiting...", webApp.name());
         webApp.stop();
         System.exit(0); // FINDBUG: this is intended in dev mode
       }
     }, 18); // enough time for the last local request to complete
   }
 }
	/**
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you 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.apache.hadoop.yarn.webapp;

	import static com.google.common.base.Preconditions.checkState;

	import java.io.IOException;
	import java.net.URI;
	import java.net.URISyntaxException;
	import java.util.Timer;
	import java.util.TimerTask;

	import javax.servlet.ServletException;
	import javax.servlet.http.Cookie;
	import javax.servlet.http.HttpServlet;
	import javax.servlet.http.HttpServletRequest;
	import javax.servlet.http.HttpServletResponse;

	import org.apache.hadoop.classification.InterfaceAudience;
	import org.apache.hadoop.http.HtmlQuoting;
	import org.apache.hadoop.yarn.webapp.Controller.RequestContext;
	import org.apache.hadoop.yarn.webapp.Router.Dest;
	import org.apache.hadoop.yarn.webapp.view.ErrorPage;
	import org.apache.hadoop.yarn.webapp.view.RobotsTextPage;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;

	import com.google.common.collect.Iterables;
	import com.google.inject.Inject;
	import com.google.inject.Injector;
	import com.google.inject.Singleton;

	/**
	* The servlet that dispatch request to various controllers
	* according to the user defined routes in the router.
	*/
	@InterfaceAudience.LimitedPrivate({"YARN", "MapReduce"})
	@Singleton
	public class Dispatcher extends HttpServlet {
	private static final long serialVersionUID = 1L;
	static final Logger LOG = LoggerFactory.getLogger(Dispatcher.class);
	static final String ERROR_COOKIE = "last-error";
	static final String STATUS_COOKIE = "last-status";

	private transient final Injector injector;
	private transient final Router router;
	private transient final WebApp webApp;
	private volatile boolean devMode = false;

	@Inject
	Dispatcher(WebApp webApp, Injector injector, Router router) {
	this.webApp = webApp;
	this.injector = injector;
	this.router = router;
	}

	@Override
	public void doOptions(HttpServletRequest req, HttpServletResponse res) {
	// for simplicity
	res.setHeader("Allow", "GET, POST");
	}

	@Override
	public void service(HttpServletRequest req, HttpServletResponse res)
	throws ServletException, IOException {
	res.setCharacterEncoding("UTF-8");
	String uri = HtmlQuoting.quoteHtmlChars(req.getRequestURI());

	if (uri == null) {
	uri = "/";
	}
	if (devMode && uri.equals("/__stop")) {
	// quick hack to restart servers in dev mode without OS commands
	res.setStatus(res.SC_NO_CONTENT);
	LOG.info("dev mode restart requested");
	prepareToExit();
	return;
	}
	// if they provide a redirectPath go there instead of going to
	// "/" so that filters can differentiate the webapps.
	if (uri.equals("/")) {
	String redirectPath = webApp.getRedirectPath();
	if (redirectPath != null && !redirectPath.isEmpty()) {
	res.sendRedirect(redirectPath);
	return;
	}
	}
	String method = req.getMethod();
	if (method.equals("OPTIONS")) {
	doOptions(req, res);
	return;
	}
	if (method.equals("TRACE")) {
	doTrace(req, res);
	return;
	}
	if (method.equals("HEAD")) {
	doGet(req, res); // default to bad request
	return;
	}
	String pathInfo = req.getPathInfo();
	if (pathInfo == null) {
	pathInfo = "/";
	}
	// The implementation class of HttpServletRequest in
	// Guice-3.0 does not decode paths that are encoded,
	// decode path info here for further operation.
	try {
	pathInfo = new URI(pathInfo).getPath();
	} catch (URISyntaxException ex) {
	// Just leave it alone for compatibility.
	LOG.error(pathInfo + ": Failed to decode path.", ex);
	}
	Controller.RequestContext rc =
	injector.getInstance(Controller.RequestContext.class);

	//short-circuit robots.txt serving for all YARN webapps.
	if (uri.equals(RobotsTextPage.ROBOTS_TXT_PATH)) {
	rc.setStatus(HttpServletResponse.SC_FOUND);
	render(RobotsTextPage.class);
	return;
	}

	if (setCookieParams(rc, req) > 0) {
	Cookie ec = rc.cookies().get(ERROR_COOKIE);
	if (ec != null) {
	rc.setStatus(Integer.parseInt(rc.cookies().
	get(STATUS_COOKIE).getValue()));
	removeErrorCookies(res, uri);
	rc.set(Params.ERROR_DETAILS, ec.getValue());
	render(ErrorPage.class);
	return;
	}
	}
	rc.prefix = webApp.name();
	Router.Dest dest = null;
	try {
	dest = router.resolve(method, pathInfo);
	} catch (WebAppException e) {
	rc.error = e;
	if (!e.getMessage().contains("not found")) {
	rc.setStatus(res.SC_INTERNAL_SERVER_ERROR);
	render(ErrorPage.class);
	return;
	}
	}
	if (dest == null) {
	rc.setStatus(res.SC_NOT_FOUND);
	render(ErrorPage.class);
	return;
	}
	rc.devMode = devMode;
	setMoreParams(rc, pathInfo, dest);
	Controller controller = injector.getInstance(dest.controllerClass);
	try {
	// TODO: support args converted from /path/:arg1/...
	dest.action.invoke(controller, (Object[]) null);
	if (!rc.rendered) {
	if (dest.defaultViewClass != null) {
	render(dest.defaultViewClass);
	} else if (rc.status == 200) {
	throw new IllegalStateException("No view rendered for 200");
	}
	}
	} catch (Exception e) {
	LOG.error("error handling URI: "+ uri, e);
	// Page could be half rendered (but still not flushed). So redirect.
	redirectToErrorPage(res, e, uri, devMode);
	}
	}

	public static void redirectToErrorPage(HttpServletResponse res, Throwable e,
	String path, boolean devMode) {
	String st = devMode ? ErrorPage.toStackTrace(e, 1024 * 3) // spec: min 4KB
	: "See logs for stack trace";
	res.setStatus(res.SC_FOUND);
	Cookie cookie = new Cookie(STATUS_COOKIE, String.valueOf(500));
	cookie.setPath(path);
	res.addCookie(cookie);
	cookie = new Cookie(ERROR_COOKIE, st);
	cookie.setPath(path);
	res.addCookie(cookie);
	res.setHeader("Location", path);
	}

	public static void removeErrorCookies(HttpServletResponse res, String path) {
	removeCookie(res, ERROR_COOKIE, path);
	removeCookie(res, STATUS_COOKIE, path);
	}

	public static void removeCookie(HttpServletResponse res, String name,
	String path) {
	LOG.debug("removing cookie {} on {}", name, path);
	Cookie c = new Cookie(name, "");
	c.setMaxAge(0);
	c.setPath(path);
	res.addCookie(c);
	}

	private void render(Class<? extends View> cls) {
	injector.getInstance(cls).render();
	}

	// /path/foo/bar with /path/:arg1/:arg2 will set {arg1=>foo, arg2=>bar}
	private void setMoreParams(RequestContext rc, String pathInfo, Dest dest) {
	checkState(pathInfo.startsWith(dest.prefix), "prefix should match");
	if (dest.pathParams.size() == 0 \|\|
	dest.prefix.length() == pathInfo.length()) {
	return;
	}
	String[] parts = Iterables.toArray(WebApp.pathSplitter.split(
	pathInfo.substring(dest.prefix.length())), String.class);
	LOG.debug("parts={}, params={}", parts, dest.pathParams);
	for (int i = 0; i < dest.pathParams.size() && i < parts.length; ++i) {
	String key = dest.pathParams.get(i);
	if (key.charAt(0) == ':') {
	rc.moreParams().put(key.substring(1), parts[i]);
	}
	}
	}

	private int setCookieParams(RequestContext rc, HttpServletRequest req) {
	Cookie[] cookies = req.getCookies();
	if (cookies != null) {
	for (Cookie cookie : cookies) {
	rc.cookies().put(cookie.getName(), cookie);
	}
	return cookies.length;
	}
	return 0;
	}

	public void setDevMode(boolean choice) {
	devMode = choice;
	}

	private void prepareToExit() {
	checkState(devMode, "only in dev mode");
	new Timer("webapp exit", true).schedule(new TimerTask() {
	@Override public void run() {
	LOG.info("WebAppp /{} exiting...", webApp.name());
	webApp.stop();
	System.exit(0); // FINDBUG: this is intended in dev mode
	}
	}, 18); // enough time for the last local request to complete
	}
	}