fix

common/utils/src/main/scala/org/apache/spark/internal/Logging.scala

@@ -110,20 +110,15 @@ trait Logging {
   }
 
   implicit class LogStringContext(val sc: StringContext) {
-    def log(args: Any*): MessageWithContext = {
+    def log(args: MDC*): MessageWithContext = {
       val processedParts = sc.parts.iterator
       val sb = new StringBuilder(processedParts.next())
       val context = new java.util.HashMap[String, String]()
 
-      args.foreach { arg =>
-        arg match {
-          case MDC(k, v) =>
-            sb.append(v)
-            if (Logging.isStructuredLoggingEnabled) {
-              context.put(k.toString.toLowerCase(Locale.ROOT), v)
-            }
-          case v: Any =>
-            sb.append(v.toString)
+      args.foreach { mdc =>
+        sb.append(mdc.value.toString)
+        if (Logging.isStructuredLoggingEnabled) {
+          context.put(mdc.key.toString.toLowerCase(Locale.ROOT), mdc.value.toString)
         }
         if (processedParts.hasNext) {
           sb.append(processedParts.next())

common/utils/src/test/scala/org/apache/spark/util/PatternLoggingSuite.scala

@@ -44,10 +44,6 @@ class PatternLoggingSuite extends LoggingSuiteBase with BeforeAndAfterAll {
   override def expectedPatternForMsgWithMDCAndException(level: Level): String =
     s""".*$level $className: Error in executor 1.\njava.lang.RuntimeException: OOM\n[\\s\\S]*"""
 
-  override def expectedPatternForVariableAndMDC(level: Level): String = {
-     s""".*$level $className: Hello This is a log message, Lost executor 1.\n"""
-  }
-
   override def expectedPatternForConcatStringAndMDC(level: Level): String = {
     s""".*$level $className: Hello This is a log message, Lost executor 1.\n"""
   }

common/utils/src/test/scala/org/apache/spark/util/StructuredLoggingSuite.scala

@@ -63,28 +63,33 @@ trait LoggingSuiteBase
     log"Max Size: ${MDC(MAX_SIZE, "4")}. " +
     log"Please double check."
 
-  def logVariableAndMDC: LogEntry =
-    log"Hello $basicMsg, Lost executor ${MDC(EXECUTOR_ID, "1")}."
+  def concatMDCAndString: LogEntry = log"Lost executor ${MDC(EXECUTOR_ID, "1")}." ++
+    s" Hello $basicMsg."
 
-  def concatMDCAndString: LogEntry =
-    log"Lost executor ${MDC(EXECUTOR_ID, "1")}." ++ s" Hello $basicMsg."
+  def concatStringAndMDC: LogEntry = s"Hello $basicMsg, " ++
+    log"Lost executor ${MDC(EXECUTOR_ID, "1")}."
 
-  def concatStringAndMDC: LogEntry =
-    s"Hello $basicMsg, " ++ log"Lost executor ${MDC(EXECUTOR_ID, "1")}."
+  // test for basic message (without any mdc)
+  def expectedPatternForBasicMsg(level: Level): String
 
+  // test for basic message and exception
+  def expectedPatternForBasicMsgWithException(level: Level): String
+
+  // test for message (with mdc)
   def expectedPatternForMsgWithMDC(level: Level): String
 
   // test for message and exception
   def expectedPatternForMsgWithMDCAndException(level: Level): String
 
-  def verifyMsgWithConcat(level: Level, logOutput: String): Unit
-
-  def expectedPatternForVariableAndMDC(level: Level): String
-
+  // test for concat string and MDC
   def expectedPatternForConcatStringAndMDC(level: Level): String
 
+  // test for concat MDC and string
   def expectedPatternForConcatMDCAndString(level: Level): String
 
+  // test for concat MDC and MDC
+  def verifyMsgWithConcat(level: Level, logOutput: String): Unit
+
   test("Basic logging") {
     Seq(
       (Level.ERROR, () => logError(basicMsg)),
@@ -140,17 +145,6 @@ trait LoggingSuiteBase
       }
   }
 
-  test("Logging variable and MDC") {
-    Seq(
-      (Level.ERROR, () => logError(logVariableAndMDC)),
-      (Level.WARN, () => logWarning(logVariableAndMDC)),
-      (Level.INFO, () => logInfo(logVariableAndMDC))).foreach {
-        case (level, logFunc) =>
-          val logOutput = captureLogOutput(logFunc)
-          assert(expectedPatternForVariableAndMDC(level).r.matches(logOutput))
-      }
-  }
-
   test("Logging concat string and MDC") {
     Seq(
       (Level.ERROR, () => logError(concatStringAndMDC)),
@@ -246,20 +240,6 @@ class StructuredLoggingSuite extends LoggingSuiteBase {
         }""")
   }
 
-  override def expectedPatternForVariableAndMDC(level: Level): String = {
-    compactAndToRegexPattern(
-      s"""
-        {
-          "ts": "<timestamp>",
-          "level": "$level",
-          "msg": "Hello This is a log message, Lost executor 1.",
-          "context": {
-             "executor_id": "1"
-          },
-          "logger": "$className"
-        }""")
-  }
-
   override def expectedPatternForConcatStringAndMDC(level: Level): String = {
     compactAndToRegexPattern(
       s"""