[SPARK-20519][SQL][CORE]Modify to prevent some possible runtime exceptions

core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala

@@ -879,7 +879,7 @@ private[spark] class PythonAccumulatorV2(
     private val serverPort: Int)
   extends CollectionAccumulator[Array[Byte]] {
 
-  Utils.checkHost(serverHost, "Expected hostname")
+  Utils.checkHost(serverHost)
 
   val bufferSize = SparkEnv.get.conf.getInt("spark.buffer.size", 65536)
 

core/src/main/scala/org/apache/spark/deploy/DeployMessage.scala

@@ -43,7 +43,7 @@ private[deploy] object DeployMessages {
       memory: Int,
       workerWebUiUrl: String)
     extends DeployMessage {
-    Utils.checkHost(host, "Required hostname")
+    Utils.checkHost(host)
     assert (port > 0)
   }
 
@@ -131,7 +131,7 @@ private[deploy] object DeployMessages {
 
   // TODO(matei): replace hostPort with host
   case class ExecutorAdded(id: Int, workerId: String, hostPort: String, cores: Int, memory: Int) {
-    Utils.checkHostPort(hostPort, "Required hostport")
+    Utils.checkHostPort(hostPort)
   }
 
   case class ExecutorUpdated(id: Int, state: ExecutorState, message: Option[String],
@@ -183,7 +183,7 @@ private[deploy] object DeployMessages {
       completedDrivers: Array[DriverInfo],
       status: MasterState) {
 
-    Utils.checkHost(host, "Required hostname")
+    Utils.checkHost(host)
     assert (port > 0)
 
     def uri: String = "spark://" + host + ":" + port
@@ -201,7 +201,7 @@ private[deploy] object DeployMessages {
     drivers: List[DriverRunner], finishedDrivers: List[DriverRunner], masterUrl: String,
     cores: Int, memory: Int, coresUsed: Int, memoryUsed: Int, masterWebUiUrl: String) {
 
-    Utils.checkHost(host, "Required hostname")
+    Utils.checkHost(host)
     assert (port > 0)
   }
 

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

@@ -80,7 +80,7 @@ private[deploy] class Master(
   private val waitingDrivers = new ArrayBuffer[DriverInfo]
   private var nextDriverNumber = 0
 
-  Utils.checkHost(address.host, "Expected hostname")
+  Utils.checkHost(address.host)
 
   private val masterMetricsSystem = MetricsSystem.createMetricsSystem("master", conf, securityMgr)
   private val applicationMetricsSystem = MetricsSystem.createMetricsSystem("applications", conf,

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

@@ -60,12 +60,12 @@ private[master] class MasterArguments(args: Array[String], conf: SparkConf) exte
   @tailrec
   private def parse(args: List[String]): Unit = args match {
     case ("--ip" | "-i") :: value :: tail =>
-      Utils.checkHost(value, "ip no longer supported, please use hostname " + value)
+      Utils.checkHost(value)
       host = value
       parse(tail)
 
     case ("--host" | "-h") :: value :: tail =>
-      Utils.checkHost(value, "Please use hostname " + value)
+      Utils.checkHost(value)
       host = value
       parse(tail)
 

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

@@ -32,7 +32,7 @@ private[spark] class WorkerInfo(
     val webUiAddress: String)
   extends Serializable {
 
-  Utils.checkHost(host, "Expected hostname")
+  Utils.checkHost(host)
   assert (port > 0)
 
   @transient var executors: mutable.HashMap[String, ExecutorDesc] = _ // executorId => info

core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala

@@ -55,7 +55,7 @@ private[deploy] class Worker(
   private val host = rpcEnv.address.host
   private val port = rpcEnv.address.port
 
-  Utils.checkHost(host, "Expected hostname")
+  Utils.checkHost(host)
   assert (port > 0)
 
   // A scheduled executor used to send messages at the specified time.

core/src/main/scala/org/apache/spark/deploy/worker/WorkerArguments.scala

@@ -68,12 +68,12 @@ private[worker] class WorkerArguments(args: Array[String], conf: SparkConf) {
   @tailrec
   private def parse(args: List[String]): Unit = args match {
     case ("--ip" | "-i") :: value :: tail =>
-      Utils.checkHost(value, "ip no longer supported, please use hostname " + value)
+      Utils.checkHost(value)
       host = value
       parse(tail)
 
     case ("--host" | "-h") :: value :: tail =>
-      Utils.checkHost(value, "Please use hostname " + value)
+      Utils.checkHost(value)
       host = value
       parse(tail)
 

core/src/main/scala/org/apache/spark/executor/Executor.scala

@@ -71,7 +71,7 @@ private[spark] class Executor(
   private val conf = env.conf
 
   // No ip or host:port - just hostname
-  Utils.checkHost(executorHostname, "Expected executed slave to be a hostname")
+  Utils.checkHost(executorHostname)
   // must not have port specified.
   assert (0 == Utils.parseHostPort(executorHostname)._2)
 

core/src/main/scala/org/apache/spark/storage/BlockManagerId.scala

@@ -46,7 +46,7 @@ class BlockManagerId private (
   def executorId: String = executorId_
 
   if (null != host_) {
-    Utils.checkHost(host_, "Expected hostname")
+    Utils.checkHost(host_)
     assert (port_ > 0)
   }
 

core/src/main/scala/org/apache/spark/util/RpcUtils.scala

@@ -28,7 +28,7 @@ private[spark] object RpcUtils {
   def makeDriverRef(name: String, conf: SparkConf, rpcEnv: RpcEnv): RpcEndpointRef = {
     val driverHost: String = conf.get("spark.driver.host", "localhost")
     val driverPort: Int = conf.getInt("spark.driver.port", 7077)
-    Utils.checkHost(driverHost, "Expected hostname")
+    Utils.checkHost(driverHost)
     rpcEnv.setupEndpointRef(RpcAddress(driverHost, driverPort), name)
   }
 

core/src/main/scala/org/apache/spark/util/Utils.scala

@@ -933,12 +933,13 @@ private[spark] object Utils extends Logging {
     customHostname.getOrElse(InetAddresses.toUriString(localIpAddress))
   }
 
-  def checkHost(host: String, message: String = "") {
-    assert(host.indexOf(':') == -1, message)
+  def checkHost(host: String) {
+    assert(host != null && host.indexOf(':') == -1, s"Expected hostname (not IP) but got $host")
   }
 
-  def checkHostPort(hostPort: String, message: String = "") {
-    assert(hostPort.indexOf(':') != -1, message)
+  def checkHostPort(hostPort: String) {
+    assert(hostPort != null && hostPort.indexOf(':') != -1,
+      s"Expected host and port but got $hostPort")
   }
 
   // Typically, this will be of order of number of nodes in cluster

resource-managers/mesos/src/main/scala/org/apache/spark/deploy/mesos/MesosClusterDispatcherArguments.scala

@@ -59,7 +59,7 @@ private[mesos] class MesosClusterDispatcherArguments(args: Array[String], conf:
   @tailrec
   private def parse(args: List[String]): Unit = args match {
     case ("--host" | "-h") :: value :: tail =>
-      Utils.checkHost(value, "Please use hostname " + value)
+      Utils.checkHost(value)
       host = value
       parse(tail)