[SPARK-27045][SQL] SQL tab in UI shows actual SQL instead of callsite in case of SparkSQLDriver

## What changes were proposed in this pull request?

When we run sql in spark via SparkSQLDriver (thrift server, spark-sql), SQL string is siet via ``setJobDescription``. the SparkUI SQL tab must show SQL instead of stacktrace in case ``setJobDescription`` is set which is more useful to end user. Instead it currently shows in description column the callsite shortform which is less useful

![image](https://user-images.githubusercontent.com/22072336/53734682-aaa7d900-3eaa-11e9-957b-0e5006db417e.png)

## How was this patch tested?

Manually:
![image](https://user-images.githubusercontent.com/22072336/53734657-9f54ad80-3eaa-11e9-8dc5-2b38f6970f4e.png)

Closes #23958 from ajithme/sqlui.

Authored-by: Ajith <ajith2489@gmail.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>

sql/catalyst/src/main/scala/org/apache/spark/sql/internal/StaticSQLConf.scala

@@ -132,4 +132,10 @@ object StaticSQLConf {
       .intConf
       .createWithDefault(1000)
 
+  val SQL_EVENT_TRUNCATE_LENGTH = buildStaticConf("spark.sql.event.truncate.length")
+    .doc("Threshold of SQL length beyond which it will be truncated before adding to " +
+      "event. Defaults to no truncation. If set to 0, callsite will be logged instead.")
+    .intConf
+    .checkValue(_ >= 0, "Must be set greater or equal to zero")
+    .createWithDefault(Int.MaxValue)
 }

sql/core/src/main/scala/org/apache/spark/sql/execution/SQLExecution.scala

@@ -20,9 +20,12 @@ package org.apache.spark.sql.execution
 import java.util.concurrent.ConcurrentHashMap
 import java.util.concurrent.atomic.AtomicLong
 
+import org.apache.spark.SparkContext
 import org.apache.spark.internal.config.Tests.IS_TESTING
 import org.apache.spark.sql.SparkSession
 import org.apache.spark.sql.execution.ui.{SparkListenerSQLExecutionEnd, SparkListenerSQLExecutionStart}
+import org.apache.spark.sql.internal.StaticSQLConf.SQL_EVENT_TRUNCATE_LENGTH
+import org.apache.spark.util.Utils
 
 object SQLExecution {
 
@@ -71,13 +74,23 @@ object SQLExecution {
       // streaming queries would give us call site like "run at <unknown>:0"
       val callSite = sc.getCallSite()
 
+      val truncateLength = sc.conf.get(SQL_EVENT_TRUNCATE_LENGTH)
+
+      val desc = Option(sc.getLocalProperty(SparkContext.SPARK_JOB_DESCRIPTION))
+        .filter(_ => truncateLength > 0)
+        .map { sqlStr =>
+          val redactedStr = Utils
+            .redact(sparkSession.sessionState.conf.stringRedactionPattern, sqlStr)
+          redactedStr.substring(0, Math.min(truncateLength, redactedStr.length))
+        }.getOrElse(callSite.shortForm)
+
       withSQLConfPropagated(sparkSession) {
         var ex: Option[Exception] = None
         val startTime = System.nanoTime()
         try {
           sc.listenerBus.post(SparkListenerSQLExecutionStart(
             executionId = executionId,
-            description = callSite.shortForm,
+            description = desc,
             details = callSite.longForm,
             physicalPlanDescription = queryExecution.toString,
             // `queryExecution.executedPlan` triggers query planning. If it fails, the exception

sql/core/src/main/scala/org/apache/spark/sql/execution/ui/AllExecutionsPage.scala

@@ -388,14 +388,15 @@ private[ui] class ExecutionPagedTable(
         +details
       </span> ++
       <div class="stage-details collapsed">
-        <pre>{execution.details}</pre>
+        <pre>{execution.description}<br></br>{execution.details}</pre>
       </div>
     } else {
       Nil
     }
 
     val desc = if (execution.description != null && execution.description.nonEmpty) {
-      <a href={executionURL(execution.executionId)}>{execution.description}</a>
+      <a href={executionURL(execution.executionId)} class="description-input">
+        {execution.description}</a>
     } else {
       <a href={executionURL(execution.executionId)}>{execution.executionId}</a>
     }