[SPARK-5495][UI] Add app and driver kill function in master web UI

Add application kill function in master web UI for standalone mode. Details can be seen in [SPARK-5495](https://issues.apache.org/jira/browse/SPARK-5495).

The snapshot of UI shows as below:
![snapshot](https://dl.dropboxusercontent.com/u/19230832/master_ui.png)

Please help to review, thanks a lot.

Author: jerryshao <saisai.shao@intel.com>

Closes #4288 from jerryshao/SPARK-5495 and squashes the following commits:

fa3e486 [jerryshao] Add some conditions
9a7be93 [jerryshao] Add kill Driver function
a239776 [jerryshao] Change the code format
ff5195d [jerryshao] Add app kill function in master web UI

core/src/main/scala/org/apache/spark/deploy/master/ApplicationState.scala

@@ -21,7 +21,7 @@ private[spark] object ApplicationState extends Enumeration {
 
   type ApplicationState = Value
 
-  val WAITING, RUNNING, FINISHED, FAILED, UNKNOWN = Value
+  val WAITING, RUNNING, FINISHED, FAILED, KILLED, UNKNOWN = Value
 
   val MAX_NUM_RETRY = 10
 }

core/src/main/scala/org/apache/spark/deploy/master/ui/MasterPage.scala

@@ -26,8 +26,8 @@ import akka.pattern.ask
 import org.json4s.JValue
 
 import org.apache.spark.deploy.JsonProtocol
-import org.apache.spark.deploy.DeployMessages.{MasterStateResponse, RequestMasterState}
-import org.apache.spark.deploy.master.{ApplicationInfo, DriverInfo, WorkerInfo}
+import org.apache.spark.deploy.DeployMessages.{RequestKillDriver, MasterStateResponse, RequestMasterState}
+import org.apache.spark.deploy.master._
 import org.apache.spark.ui.{WebUIPage, UIUtils}
 import org.apache.spark.util.Utils
 
@@ -41,6 +41,31 @@ private[spark] class MasterPage(parent: MasterWebUI) extends WebUIPage("") {
     JsonProtocol.writeMasterState(state)
   }
 
+  def handleAppKillRequest(request: HttpServletRequest): Unit = {
+    handleKillRequest(request, id => {
+      parent.master.idToApp.get(id).foreach { app =>
+        parent.master.removeApplication(app, ApplicationState.KILLED)
+      }
+    })
+  }
+
+  def handleDriverKillRequest(request: HttpServletRequest): Unit = {
+    handleKillRequest(request, id => { master ! RequestKillDriver(id) })
+  }
+
+  private def handleKillRequest(request: HttpServletRequest, action: String => Unit): Unit = {
+    if (parent.killEnabled &&
+        parent.master.securityMgr.checkModifyPermissions(request.getRemoteUser)) {
+      val killFlag = Option(request.getParameter("terminate")).getOrElse("false").toBoolean
+      val id = Option(request.getParameter("id"))
+      if (id.isDefined && killFlag) {
+        action(id.get)
+      }
+
+      Thread.sleep(100)
+    }
+  }
+
   /** Index view listing applications and executors */
   def render(request: HttpServletRequest): Seq[Node] = {
     val stateFuture = (master ? RequestMasterState)(timeout).mapTo[MasterStateResponse]
@@ -167,9 +192,20 @@ private[spark] class MasterPage(parent: MasterWebUI) extends WebUIPage("") {
   }
 
   private def appRow(app: ApplicationInfo, active: Boolean): Seq[Node] = {
+    val killLink = if (parent.killEnabled &&
+      (app.state == ApplicationState.RUNNING || app.state == ApplicationState.WAITING)) {
+    val killLinkUri = s"app/kill?id=${app.id}&terminate=true"
+    val confirm = "return window.confirm(" +
+      s"'Are you sure you want to kill application ${app.id} ?');"
+      <span class="kill-link">
+        (<a href={killLinkUri} onclick={confirm}>kill</a>)
+      </span>
+    }
+
     <tr>
       <td>
         <a href={"app?appId=" + app.id}>{app.id}</a>
+        {killLink}
       </td>
       <td>
         <a href={app.desc.appUiUrl}>{app.desc.name}</a>
@@ -203,8 +239,19 @@ private[spark] class MasterPage(parent: MasterWebUI) extends WebUIPage("") {
   }
 
   private def driverRow(driver: DriverInfo): Seq[Node] = {
+    val killLink = if (parent.killEnabled &&
+      (driver.state == DriverState.RUNNING ||
+        driver.state == DriverState.SUBMITTED ||
+        driver.state == DriverState.RELAUNCHING)) {
+    val killLinkUri = s"driver/kill?id=${driver.id}&terminate=true"
+    val confirm = "return window.confirm(" +
+      s"'Are you sure you want to kill driver ${driver.id} ?');"
+      <span class="kill-link">
+        (<a href={killLinkUri} onclick={confirm}>kill</a>)
+      </span>
+    }
     <tr>
-      <td>{driver.id} </td>
+      <td>{driver.id} {killLink}</td>
       <td>{driver.submitDate}</td>
       <td>{driver.worker.map(w => <a href={w.webUiAddress}>{w.id.toString}</a>).getOrElse("None")}
       </td>

core/src/main/scala/org/apache/spark/deploy/master/ui/MasterWebUI.scala

@@ -32,15 +32,21 @@ class MasterWebUI(val master: Master, requestedPort: Int)
 
   val masterActorRef = master.self
   val timeout = AkkaUtils.askTimeout(master.conf)
+  val killEnabled = master.conf.getBoolean("spark.ui.killEnabled", true)
 
   initialize()
 
   /** Initialize all components of the server. */
   def initialize() {
+    val masterPage = new MasterPage(this)
     attachPage(new ApplicationPage(this))
     attachPage(new HistoryNotFoundPage(this))
-    attachPage(new MasterPage(this))
+    attachPage(masterPage)
     attachHandler(createStaticHandler(MasterWebUI.STATIC_RESOURCE_DIR, "/static"))
+    attachHandler(
+      createRedirectHandler("/app/kill", "/", masterPage.handleAppKillRequest))
+    attachHandler(
+      createRedirectHandler("/driver/kill", "/", masterPage.handleDriverKillRequest))
   }
 
   /** Attach a reconstructed UI to this Master UI. Only valid after bind(). */