src/mapred/org/apache/hadoop/mapred/StatusHttpServer.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.mapred;

 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.PrintWriter;
 import java.net.URL;
 import java.net.InetSocketAddress;

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

 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.util.ReflectionUtils;
 import org.mortbay.http.HttpContext;
 import org.mortbay.http.SocketListener;
 import org.mortbay.http.SslListener;
 import org.mortbay.http.handler.ResourceHandler;
 import org.mortbay.jetty.servlet.WebApplicationContext;

 /**
  * Create a Jetty embedded server to answer http requests. The primary goal
  * is to serve up status information for the server.
  * There are three contexts:
  *   "/logs/" -> points to the log directory
  *   "/static/" -> points to common static files (src/webapps/static)
  *   "/" -> the jsp server code from (src/webapps/<name>)
  */
 public class StatusHttpServer {
   private org.mortbay.jetty.Server webServer;
   private SocketListener listener;
   private SslListener sslListener;
   private boolean findPort;
   private WebApplicationContext webAppContext;
   private static final Log LOG =
     LogFactory.getLog(StatusHttpServer.class.getName());

   /**
    * Create a status server on the given port.
    * The jsp scripts are taken from src/webapps/<name>.
    * @param name The name of the server
    * @param port The port to use on the server
    * @param findPort whether the server should start at the given port and
    *        increment by 1 until it finds a free port.
    */
   public StatusHttpServer(String name, String bindAddress, int port,
                           boolean findPort) throws IOException {
     webServer = new org.mortbay.jetty.Server();
     this.findPort = findPort;
     listener = new SocketListener();
     listener.setPort(port);
     listener.setHost(bindAddress);
     webServer.addListener(listener);

     // set up the context for "/logs/" if "hadoop.log.dir" property is defined.
     String logDir = System.getProperty("hadoop.log.dir");
     if (logDir != null) {
       HttpContext logContext = new HttpContext();
       logContext.setContextPath("/logs/*");
       logContext.setResourceBase(logDir);
       logContext.addHandler(new ResourceHandler());
       webServer.addContext(logContext);
     }

     // set up the context for "/static/*"
     String appDir = getWebAppsPath();
     HttpContext staticContext = new HttpContext();
     staticContext.setContextPath("/static/*");
     staticContext.setResourceBase(appDir + "/static");
     staticContext.addHandler(new ResourceHandler());
     webServer.addContext(staticContext);

     // set up the context for "/" jsp files
     webAppContext =
       webServer.addWebApplication("/", appDir + "/" + name);
     addServlet("stacks", "/stacks", StackServlet.class);
     addServlet("reducegraph", "/taskgraph", TaskGraphServlet.class);
     addServlet("logLevel", "/logLevel",
         org.apache.hadoop.log.LogLevel.Servlet.class);
   }

   /**
    * Set a value in the webapp context. These values are available to the jsp
    * pages as "application.getAttribute(name)".
    * @param name The name of the attribute
    * @param value The value of the attribute
    */
   public void setAttribute(String name, Object value) {
     webAppContext.setAttribute(name, value);
   }

   /**
    * Add a servlet in the server.
    * @param name The name of the servlet (can be passed as null)
    * @param pathSpec The path spec for the servlet
    * @param servletClass The servlet class
    */
   public <T extends HttpServlet>
    void addServlet(String name, String pathSpec,
                    Class<T> servletClass) {

     WebApplicationContext context = webAppContext;
     try {
       if (name == null) {
         context.addServlet(pathSpec, servletClass.getName());
       } else {
         context.addServlet(name, pathSpec, servletClass.getName());
       }
     } catch (ClassNotFoundException ex) {
       throw makeRuntimeException("Problem instantiating class", ex);
     } catch (InstantiationException ex) {
       throw makeRuntimeException("Problem instantiating class", ex);
     } catch (IllegalAccessException ex) {
       throw makeRuntimeException("Problem instantiating class", ex);
     }
   }

   private static RuntimeException makeRuntimeException(String msg,
                                                        Throwable cause) {
     RuntimeException result = new RuntimeException(msg);
     if (cause != null) {
       result.initCause(cause);
     }
     return result;
   }

   /**
    * Get the value in the webapp context.
    * @param name The name of the attribute
    * @return The value of the attribute
    */
   public Object getAttribute(String name) {
     return webAppContext.getAttribute(name);
   }

   /**
    * Get the pathname to the webapps files.
    * @return the pathname as a URL
    */
   private static String getWebAppsPath() throws IOException {
     URL url = StatusHttpServer.class.getClassLoader().getResource("webapps");
     if (url == null)
       throw new IOException("webapps not found in CLASSPATH");
     return url.toString();
   }

   /**
    * Get the port that the server is on
    * @return the port
    */
   public int getPort() {
     return listener.getPort();
   }

   public void setThreads(int min, int max) {
     listener.setMinThreads(min);
     listener.setMaxThreads(max);
   }

   /**
    * Configure an ssl listener on the server.
    * @param addr address to listen on
    * @param keystore location of the keystore
    * @param storPass password for the keystore
    * @param keyPass password for the key
    */
   public void addSslListener(InetSocketAddress addr, String keystore,
       String storPass, String keyPass) throws IOException {
     if (sslListener != null || webServer.isStarted()) {
       throw new IOException("Failed to add ssl listener");
     }
     sslListener = new SslListener();
     sslListener.setHost(addr.getHostName());
     sslListener.setPort(addr.getPort());
     sslListener.setKeystore(keystore);
     sslListener.setPassword(storPass);
     sslListener.setKeyPassword(keyPass);
     webServer.addListener(sslListener);
   }

   /**
    * Start the server. Does not wait for the server to start.
    */
   public void start() throws IOException {
     try {
       while (true) {
         try {
           webServer.start();
           break;
         } catch (org.mortbay.util.MultiException ex) {
           // if the multi exception contains ONLY a bind exception,
           // then try the next port number.
           boolean needNewPort = false;
           if(ex.size() == 1) {
             Exception sub = ex.getException(0);
             if (sub instanceof java.net.BindException) {
               if(!findPort)
                 throw sub; // java.net.BindException
               needNewPort = true;
             }
           }
           if (!needNewPort)
             throw ex;
           listener.setPort(listener.getPort() + 1);
         }
       }
     } catch (IOException ie) {
       throw ie;
     } catch (Exception e) {
       IOException ie = new IOException("Problem starting http server");
       ie.initCause(e);
       throw ie;
     }
   }

   /**
    * stop the server
    */
   public void stop() throws InterruptedException {
     webServer.stop();
   }

   /**
    * A very simple servlet to serve up a text representation of the current
    * stack traces. It both returns the stacks to the caller and logs them.
    * Currently the stack traces are done sequentially rather than exactly the
    * same data.
    */
   public static class StackServlet extends HttpServlet {

     private static final long serialVersionUID = -6284183679759467039L;

     @Override
     public void doGet(HttpServletRequest request, HttpServletResponse response)
       throws ServletException, IOException {

       OutputStream outStream = response.getOutputStream();
       ReflectionUtils.printThreadInfo(new PrintWriter(outStream), "");
       outStream.close();
       ReflectionUtils.logThreadInfo(LOG, "jsp requested", 1);
     }
   }

   /** The servlet that outputs svg graphics for map / reduce task
    *  statuses
    */
   public static class TaskGraphServlet extends HttpServlet {

     private static final long serialVersionUID = -1365683739392460020L;

     /**height of the graph w/o margins*/
     public static final int width = 600;

     /**height of the graph w/o margins*/
     public static final int height = 200;

     /**margin space on y axis */
     public static final int ymargin = 20;

     /**margin space on x axis */
     public static final int xmargin = 80;

     private static final float oneThird = 1f / 3f;

     @Override
     public void doGet(HttpServletRequest request, HttpServletResponse response)
       throws ServletException, IOException {

       response.setContentType("image/svg+xml");

       JobTracker tracker =
         (JobTracker) getServletContext().getAttribute("job.tracker");

       String jobIdStr = request.getParameter("jobid");
       if(jobIdStr == null)
         return;
       JobID jobId = JobID.forName(jobIdStr);
       String typeStr = request.getParameter("type");
       boolean isMap = false;
       if("map".equalsIgnoreCase(typeStr)) {
         isMap = true;
       }

       PrintWriter out = response.getWriter();
       TaskReport[] reports = null;

       reports = isMap ? tracker.getMapTaskReports(jobId)
                       : tracker.getReduceTaskReports(jobId);

       int numTasks = reports.length;
       if(numTasks <= 0) {
         return;
       }

       int tasksPerBar = (int)Math.ceil(numTasks / 600d);
       int numBars = (int) Math.ceil((double)numTasks / tasksPerBar);
       int w = Math.max(600, numBars);
       int barWidth = Math.min(10,  w / numBars); //min 1px, max 10px
       int barsPerNotch = (int)Math.ceil(10d / barWidth);
       w = w + numBars / barsPerNotch;
       int totalWidth = w + 2 * xmargin;

       //draw a white rectangle
       out.print("<?xml version=\"1.0\" standalone=\"no\"?>\n" +
         "<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.1//EN\" \n" +
         "\"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\">\n" +
         "<?xml-stylesheet type=\"text/css\" href=\"/static/hadoop.css\"?>\n\n"+
         "<svg width=\"");out.print(totalWidth);
       out.print("\" height=\"");out.print(height + 2 * ymargin);
       out.print("\" version=\"1.1\"\n" +
         "xmlns=\"http://www.w3.org/2000/svg\">\n\n");

       //axes
       printLine(out, xmargin - 1, xmargin - 1, height + ymargin + 1
           , ymargin - 1, "black" );
       printLine(out, xmargin - 1, w + xmargin + 1 ,height + ymargin + 1
           , height + ymargin + 1, "black" );

       //borderlines
       printLine(out, w + xmargin + 1 , w + xmargin +1
           , height + ymargin + 1,ymargin - 1, "#CCCCCC" );
       printLine(out, xmargin - 1, w + xmargin + 1
           , ymargin - 1 , ymargin - 1, "#CCCCCC" );

       String[]  colors = new String[] {"#00DD00", "#E50000", "#AAAAFF"};

       //determine the notch interval using the number of digits for numTasks
       int xNotchInterval = (int)(Math.ceil( numTasks / 10d));

       int xOffset = -1;
       int xNotchCount = 0;
       //task bar graph
       if(reports != null) {
         for(int i=0, barCnt=0; ;i+=tasksPerBar, barCnt++) {
           if(barCnt % barsPerNotch == 0) {
             xOffset++;
           }
           int x = barCnt * barWidth + xmargin + xOffset;
           //x axis notches
           if(i >= xNotchInterval * xNotchCount) {
             printLine(out, x, x, height + ymargin + 3
                 , height + ymargin - 2, "black");
             printText(out, x, height + ymargin + 15
                 , String.valueOf(xNotchInterval * xNotchCount++ ), "middle");
           }
           if(i >= reports.length) break;

           if(isMap) {
             float progress = getMapAvarageProgress(tasksPerBar, i, reports);
             int barHeight = (int)Math.ceil(height * progress);
             int y = height - barHeight + ymargin;
             printRect(out, barWidth, barHeight,x , y , colors[2]);
           }
           else {
             float[] progresses
               = getReduceAvarageProgresses(tasksPerBar, i, reports);
             //draw three bars stacked, for copy, sort, reduce

             int prevHeight =0;
             for(int j=0; j < 3 ; j++) {
               int barHeight = (int)((height / 3) * progresses[j]);
               if(barHeight > height/ 3 - 3)//fix rounding error
                 barHeight = height / 3 + 1;

               int y = height - barHeight + ymargin - prevHeight;
               prevHeight += barHeight;
               printRect(out, barWidth, barHeight, x, y, colors[j] );
             }
           }
         }
       }

       //y axis notches
       for(int i=0;i<=10;i++) {
         printLine(out, xmargin-3 , xmargin+2 , ymargin + (i * height) / 10
             , ymargin + (i * height) / 10 , "black");
         printText(out, xmargin - 10 , ymargin + 4 + (i * height) / 10
             , String.valueOf(100 - i * 10), "end");
       }

       if(!isMap) {
         //print color codes for copy, sort, reduce
         printRect(out, 14, 14, xmargin + w + 4, ymargin + 20, colors[0]);
         printText(out, xmargin + w + 24, ymargin + 30, "copy", "start");
         printRect(out, 14, 14, xmargin + w + 4, ymargin + 50, colors[1]);
         printText(out, xmargin + w + 24, ymargin + 60, "sort", "start");
         printRect(out, 14, 14, xmargin + w + 4, ymargin + 80, colors[2]);
         printText(out, xmargin + w + 24, ymargin + 90, "reduce", "start");
       }


       //firefox curently does not support vertical text
       //out.print("<text x=\"");out.print(6);
       //out.print("\" y=\""); out.print(ymargin + height / 2);
       //out.print("\" style=\"text-anchor:middle;writing-mode:tb\">"
       //+"Percent</text>\n");

       out.print("</svg>");
     }

     /**Computes average progress per bar*/
     private float getMapAvarageProgress(int tasksPerBar, int index
         , TaskReport[] reports ) {
       float progress = 0f;
       int k=0;
       for(;k < tasksPerBar && index + k < reports.length; k++) {
         progress += reports[index + k].getProgress();
       }
       progress /= k;
       return progress;
     }

     /**Computes average progresses per bar*/
     private float[] getReduceAvarageProgresses(int tasksPerBar, int index
         , TaskReport[] reports ) {
       float[] progresses = new float[] {0,0,0};
       int k=0;
       for(;k < tasksPerBar && index + k < reports.length; k++) {
         float progress = reports[index+k].getProgress();
         for(int j=0; progress > 0 ; j++, progress -= oneThird) {
           if(progress > oneThird)
             progresses[j] += 1f;
           else
             progresses[j] += progress * 3 ;
         }
       }
       for(int j=0; j<3; j++) { progresses[j] /= k;}

       return progresses;
     }

     private void printRect(PrintWriter out, int width, int height
         , int x, int y, String color) throws IOException {
       if(height > 0) {
         out.print("<rect width=\"");out.print(width);
         out.print("\" height=\"");  out.print(height);
         out.print("\" x=\""); out.print(x);
         out.print("\" y=\""); out.print(y);
         out.print("\" style=\"fill:"); out.print(color);out.print("\"/>\n");
       }
     }
     private void printLine(PrintWriter out, int x1, int x2
         , int y1, int y2, String color) throws IOException {
       out.print("<line x1=\"");out.print(x1);
       out.print("\" x2=\"");out.print(x2);
       out.print("\" y1=\"");out.print(y1);
       out.print("\" y2=\""); out.print(y2);
       out.print("\" class=\"taskgraphline\" style=\"stroke:");
       out.print(color); out.print("\"/>\n");
     }
     private void printText(PrintWriter out, int x, int y, String text
         , String anchor) throws IOException {
       out.print("<text x=\"");out.print(String.valueOf(x));
       out.print("\" y=\""); out.print(String.valueOf(y));
       out.print("\" style=\"fill:black;font-family:sans-serif;"
           + "text-anchor:");out.print(anchor); out.print("\">");
       out.print(text); out.print("</text>\n");
     }
   }

 }
	/**
	* 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.mapred;

	import java.io.IOException;
	import java.io.OutputStream;
	import java.io.PrintWriter;
	import java.net.URL;
	import java.net.InetSocketAddress;

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

	import org.apache.commons.logging.Log;
	import org.apache.commons.logging.LogFactory;
	import org.apache.hadoop.util.ReflectionUtils;
	import org.mortbay.http.HttpContext;
	import org.mortbay.http.SocketListener;
	import org.mortbay.http.SslListener;
	import org.mortbay.http.handler.ResourceHandler;
	import org.mortbay.jetty.servlet.WebApplicationContext;

	/**
	* Create a Jetty embedded server to answer http requests. The primary goal
	* is to serve up status information for the server.
	* There are three contexts:
	* "/logs/" -> points to the log directory
	* "/static/" -> points to common static files (src/webapps/static)
	* "/" -> the jsp server code from (src/webapps/<name>)
	*/
	public class StatusHttpServer {
	private org.mortbay.jetty.Server webServer;
	private SocketListener listener;
	private SslListener sslListener;
	private boolean findPort;
	private WebApplicationContext webAppContext;
	private static final Log LOG =
	LogFactory.getLog(StatusHttpServer.class.getName());

	/**
	* Create a status server on the given port.
	* The jsp scripts are taken from src/webapps/<name>.
	* @param name The name of the server
	* @param port The port to use on the server
	* @param findPort whether the server should start at the given port and
	* increment by 1 until it finds a free port.
	*/
	public StatusHttpServer(String name, String bindAddress, int port,
	boolean findPort) throws IOException {
	webServer = new org.mortbay.jetty.Server();
	this.findPort = findPort;
	listener = new SocketListener();
	listener.setPort(port);
	listener.setHost(bindAddress);
	webServer.addListener(listener);

	// set up the context for "/logs/" if "hadoop.log.dir" property is defined.
	String logDir = System.getProperty("hadoop.log.dir");
	if (logDir != null) {
	HttpContext logContext = new HttpContext();
	logContext.setContextPath("/logs/*");
	logContext.setResourceBase(logDir);
	logContext.addHandler(new ResourceHandler());
	webServer.addContext(logContext);
	}

	// set up the context for "/static/*"
	String appDir = getWebAppsPath();
	HttpContext staticContext = new HttpContext();
	staticContext.setContextPath("/static/*");
	staticContext.setResourceBase(appDir + "/static");
	staticContext.addHandler(new ResourceHandler());
	webServer.addContext(staticContext);

	// set up the context for "/" jsp files
	webAppContext =
	webServer.addWebApplication("/", appDir + "/" + name);
	addServlet("stacks", "/stacks", StackServlet.class);
	addServlet("reducegraph", "/taskgraph", TaskGraphServlet.class);
	addServlet("logLevel", "/logLevel",
	org.apache.hadoop.log.LogLevel.Servlet.class);
	}

	/**
	* Set a value in the webapp context. These values are available to the jsp
	* pages as "application.getAttribute(name)".
	* @param name The name of the attribute
	* @param value The value of the attribute
	*/
	public void setAttribute(String name, Object value) {
	webAppContext.setAttribute(name, value);
	}

	/**
	* Add a servlet in the server.
	* @param name The name of the servlet (can be passed as null)
	* @param pathSpec The path spec for the servlet
	* @param servletClass The servlet class
	*/
	public <T extends HttpServlet>
	void addServlet(String name, String pathSpec,
	Class<T> servletClass) {

	WebApplicationContext context = webAppContext;
	try {
	if (name == null) {
	context.addServlet(pathSpec, servletClass.getName());
	} else {
	context.addServlet(name, pathSpec, servletClass.getName());
	}
	} catch (ClassNotFoundException ex) {
	throw makeRuntimeException("Problem instantiating class", ex);
	} catch (InstantiationException ex) {
	throw makeRuntimeException("Problem instantiating class", ex);
	} catch (IllegalAccessException ex) {
	throw makeRuntimeException("Problem instantiating class", ex);
	}
	}

	private static RuntimeException makeRuntimeException(String msg,
	Throwable cause) {
	RuntimeException result = new RuntimeException(msg);
	if (cause != null) {
	result.initCause(cause);
	}
	return result;
	}

	/**
	* Get the value in the webapp context.
	* @param name The name of the attribute
	* @return The value of the attribute
	*/
	public Object getAttribute(String name) {
	return webAppContext.getAttribute(name);
	}

	/**
	* Get the pathname to the webapps files.
	* @return the pathname as a URL
	*/
	private static String getWebAppsPath() throws IOException {
	URL url = StatusHttpServer.class.getClassLoader().getResource("webapps");
	if (url == null)
	throw new IOException("webapps not found in CLASSPATH");
	return url.toString();
	}

	/**
	* Get the port that the server is on
	* @return the port
	*/
	public int getPort() {
	return listener.getPort();
	}

	public void setThreads(int min, int max) {
	listener.setMinThreads(min);
	listener.setMaxThreads(max);
	}

	/**
	* Configure an ssl listener on the server.
	* @param addr address to listen on
	* @param keystore location of the keystore
	* @param storPass password for the keystore
	* @param keyPass password for the key
	*/
	public void addSslListener(InetSocketAddress addr, String keystore,
	String storPass, String keyPass) throws IOException {
	if (sslListener != null \|\| webServer.isStarted()) {
	throw new IOException("Failed to add ssl listener");
	}
	sslListener = new SslListener();
	sslListener.setHost(addr.getHostName());
	sslListener.setPort(addr.getPort());
	sslListener.setKeystore(keystore);
	sslListener.setPassword(storPass);
	sslListener.setKeyPassword(keyPass);
	webServer.addListener(sslListener);
	}

	/**
	* Start the server. Does not wait for the server to start.
	*/
	public void start() throws IOException {
	try {
	while (true) {
	try {
	webServer.start();
	break;
	} catch (org.mortbay.util.MultiException ex) {
	// if the multi exception contains ONLY a bind exception,
	// then try the next port number.
	boolean needNewPort = false;
	if(ex.size() == 1) {
	Exception sub = ex.getException(0);
	if (sub instanceof java.net.BindException) {
	if(!findPort)
	throw sub; // java.net.BindException
	needNewPort = true;
	}
	}
	if (!needNewPort)
	throw ex;
	listener.setPort(listener.getPort() + 1);
	}
	}
	} catch (IOException ie) {
	throw ie;
	} catch (Exception e) {
	IOException ie = new IOException("Problem starting http server");
	ie.initCause(e);
	throw ie;
	}
	}

	/**
	* stop the server
	*/
	public void stop() throws InterruptedException {
	webServer.stop();
	}

	/**
	* A very simple servlet to serve up a text representation of the current
	* stack traces. It both returns the stacks to the caller and logs them.
	* Currently the stack traces are done sequentially rather than exactly the
	* same data.
	*/
	public static class StackServlet extends HttpServlet {

	private static final long serialVersionUID = -6284183679759467039L;

	@Override
	public void doGet(HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException {

	OutputStream outStream = response.getOutputStream();
	ReflectionUtils.printThreadInfo(new PrintWriter(outStream), "");
	outStream.close();
	ReflectionUtils.logThreadInfo(LOG, "jsp requested", 1);
	}
	}

	/** The servlet that outputs svg graphics for map / reduce task
	* statuses
	*/
	public static class TaskGraphServlet extends HttpServlet {

	private static final long serialVersionUID = -1365683739392460020L;

	/*height of the graph w/o margins/
	public static final int width = 600;

	/*height of the graph w/o margins/
	public static final int height = 200;

	/*margin space on y axis /
	public static final int ymargin = 20;

	/*margin space on x axis /
	public static final int xmargin = 80;

	private static final float oneThird = 1f / 3f;

	@Override
	public void doGet(HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException {

	response.setContentType("image/svg+xml");

	JobTracker tracker =
	(JobTracker) getServletContext().getAttribute("job.tracker");

	String jobIdStr = request.getParameter("jobid");
	if(jobIdStr == null)
	return;
	JobID jobId = JobID.forName(jobIdStr);
	String typeStr = request.getParameter("type");
	boolean isMap = false;
	if("map".equalsIgnoreCase(typeStr)) {
	isMap = true;
	}

	PrintWriter out = response.getWriter();
	TaskReport[] reports = null;

	reports = isMap ? tracker.getMapTaskReports(jobId)
	: tracker.getReduceTaskReports(jobId);

	int numTasks = reports.length;
	if(numTasks <= 0) {
	return;
	}

	int tasksPerBar = (int)Math.ceil(numTasks / 600d);
	int numBars = (int) Math.ceil((double)numTasks / tasksPerBar);
	int w = Math.max(600, numBars);
	int barWidth = Math.min(10, w / numBars); //min 1px, max 10px
	int barsPerNotch = (int)Math.ceil(10d / barWidth);
	w = w + numBars / barsPerNotch;
	int totalWidth = w + 2 * xmargin;

	//draw a white rectangle
	out.print("<?xml version=\"1.0\" standalone=\"no\"?>\n" +
	"<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.1//EN\" \n" +
	"\"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\">\n" +
	"<?xml-stylesheet type=\"text/css\" href=\"/static/hadoop.css\"?>\n\n"+
	"<svg width=\"");out.print(totalWidth);
	out.print("\" height=\"");out.print(height + 2 * ymargin);
	out.print("\" version=\"1.1\"\n" +
	"xmlns=\"http://www.w3.org/2000/svg\">\n\n");

	//axes
	printLine(out, xmargin - 1, xmargin - 1, height + ymargin + 1
	, ymargin - 1, "black" );
	printLine(out, xmargin - 1, w + xmargin + 1 ,height + ymargin + 1
	, height + ymargin + 1, "black" );

	//borderlines
	printLine(out, w + xmargin + 1 , w + xmargin +1
	, height + ymargin + 1,ymargin - 1, "#CCCCCC" );
	printLine(out, xmargin - 1, w + xmargin + 1
	, ymargin - 1 , ymargin - 1, "#CCCCCC" );

	String[] colors = new String[] {"#00DD00", "#E50000", "#AAAAFF"};

	//determine the notch interval using the number of digits for numTasks
	int xNotchInterval = (int)(Math.ceil( numTasks / 10d));

	int xOffset = -1;
	int xNotchCount = 0;
	//task bar graph
	if(reports != null) {
	for(int i=0, barCnt=0; ;i+=tasksPerBar, barCnt++) {
	if(barCnt % barsPerNotch == 0) {
	xOffset++;
	}
	int x = barCnt * barWidth + xmargin + xOffset;
	//x axis notches
	if(i >= xNotchInterval * xNotchCount) {
	printLine(out, x, x, height + ymargin + 3
	, height + ymargin - 2, "black");
	printText(out, x, height + ymargin + 15
	, String.valueOf(xNotchInterval * xNotchCount++ ), "middle");
	}
	if(i >= reports.length) break;

	if(isMap) {
	float progress = getMapAvarageProgress(tasksPerBar, i, reports);
	int barHeight = (int)Math.ceil(height * progress);
	int y = height - barHeight + ymargin;
	printRect(out, barWidth, barHeight,x , y , colors[2]);
	}
	else {
	float[] progresses
	= getReduceAvarageProgresses(tasksPerBar, i, reports);
	//draw three bars stacked, for copy, sort, reduce

	int prevHeight =0;
	for(int j=0; j < 3 ; j++) {
	int barHeight = (int)((height / 3) * progresses[j]);
	if(barHeight > height/ 3 - 3)//fix rounding error
	barHeight = height / 3 + 1;

	int y = height - barHeight + ymargin - prevHeight;
	prevHeight += barHeight;
	printRect(out, barWidth, barHeight, x, y, colors[j] );
	}
	}
	}
	}

	//y axis notches
	for(int i=0;i<=10;i++) {
	printLine(out, xmargin-3 , xmargin+2 , ymargin + (i * height) / 10
	, ymargin + (i * height) / 10 , "black");
	printText(out, xmargin - 10 , ymargin + 4 + (i * height) / 10
	, String.valueOf(100 - i * 10), "end");
	}

	if(!isMap) {
	//print color codes for copy, sort, reduce
	printRect(out, 14, 14, xmargin + w + 4, ymargin + 20, colors[0]);
	printText(out, xmargin + w + 24, ymargin + 30, "copy", "start");
	printRect(out, 14, 14, xmargin + w + 4, ymargin + 50, colors[1]);
	printText(out, xmargin + w + 24, ymargin + 60, "sort", "start");
	printRect(out, 14, 14, xmargin + w + 4, ymargin + 80, colors[2]);
	printText(out, xmargin + w + 24, ymargin + 90, "reduce", "start");
	}


	//firefox curently does not support vertical text
	//out.print("<text x=\"");out.print(6);
	//out.print("\" y=\""); out.print(ymargin + height / 2);
	//out.print("\" style=\"text-anchor:middle;writing-mode:tb\">"
	//+"Percent</text>\n");

	out.print("</svg>");
	}

	/*Computes average progress per bar/
	private float getMapAvarageProgress(int tasksPerBar, int index
	, TaskReport[] reports ) {
	float progress = 0f;
	int k=0;
	for(;k < tasksPerBar && index + k < reports.length; k++) {
	progress += reports[index + k].getProgress();
	}
	progress /= k;
	return progress;
	}

	/*Computes average progresses per bar/
	private float[] getReduceAvarageProgresses(int tasksPerBar, int index
	, TaskReport[] reports ) {
	float[] progresses = new float[] {0,0,0};
	int k=0;
	for(;k < tasksPerBar && index + k < reports.length; k++) {
	float progress = reports[index+k].getProgress();
	for(int j=0; progress > 0 ; j++, progress -= oneThird) {
	if(progress > oneThird)
	progresses[j] += 1f;
	else
	progresses[j] += progress * 3 ;
	}
	}
	for(int j=0; j<3; j++) { progresses[j] /= k;}

	return progresses;
	}

	private void printRect(PrintWriter out, int width, int height
	, int x, int y, String color) throws IOException {
	if(height > 0) {
	out.print("<rect width=\"");out.print(width);
	out.print("\" height=\""); out.print(height);
	out.print("\" x=\""); out.print(x);
	out.print("\" y=\""); out.print(y);
	out.print("\" style=\"fill:"); out.print(color);out.print("\"/>\n");
	}
	}
	private void printLine(PrintWriter out, int x1, int x2
	, int y1, int y2, String color) throws IOException {
	out.print("<line x1=\"");out.print(x1);
	out.print("\" x2=\"");out.print(x2);
	out.print("\" y1=\"");out.print(y1);
	out.print("\" y2=\""); out.print(y2);
	out.print("\" class=\"taskgraphline\" style=\"stroke:");
	out.print(color); out.print("\"/>\n");
	}
	private void printText(PrintWriter out, int x, int y, String text
	, String anchor) throws IOException {
	out.print("<text x=\"");out.print(String.valueOf(x));
	out.print("\" y=\""); out.print(String.valueOf(y));
	out.print("\" style=\"fill:black;font-family:sans-serif;"
	+ "text-anchor:");out.print(anchor); out.print("\">");
	out.print(text); out.print("</text>\n");
	}
	}

	}