Warn on finished span in runWithSpan

core/kamon-core/src/main/scala/kamon/ContextStorage.scala

@@ -18,6 +18,7 @@ package kamon
 
 import kamon.context.{Context, Storage}
 import kamon.trace.Span
+import org.slf4j.LoggerFactory
 
 import scala.util.control.NonFatal
 
@@ -28,6 +29,7 @@ import scala.util.control.NonFatal
 trait ContextStorage {
   import ContextStorage._
 
+  private val log = LoggerFactory.getLogger(classOf[ContextStorage])
   /**
     * Returns the current Context on Kamon's Context Storage. As the default behavior, this will return Context.Empty if
     * no other Context has been stored on the calling thread.
@@ -118,6 +120,9 @@ trait ContextStorage {
     */
   @inline def runWithSpan[T](span: Span, finishSpan: Boolean)(f: => T): T = {
     try {
+      if (span.isFinished) {
+        log.warn(s"Running with a finished span: ${span},${span.operationName()}")
+      }
       runWithContextEntry(Span.Key, span)(f)
     } catch {
       case NonFatal(t) =>

core/kamon-core/src/main/scala/kamon/trace/Span.scala

@@ -77,6 +77,11 @@ sealed abstract class Span extends Sampler.Operation {
     */
   def trace: Trace
 
+  /**
+    * Returns true if this Span was finished.
+    */
+  def isFinished: Boolean
+
   /**
     * Returns true if this Span was initially created in another process and then transferred to this process.
     */
@@ -426,6 +431,7 @@ object Span {
 
     override val isRemote: Boolean = false
     override val isEmpty: Boolean = false
+    override val isFinished: Boolean = _isOpen
 
     override def start(): Delayed =
       start(clock.instant())
@@ -679,6 +685,7 @@ object Span {
     override def kind: Kind = Kind.Unknown
     override def isRemote: Boolean = false
     override def isEmpty: Boolean = true
+    override def isFinished: Boolean = false
     override def position(): Position = Position.Unknown
     override def tag(key: String, value: String): Span = this
     override def tag(key: String, value: Long): Span = this
@@ -715,6 +722,7 @@ object Span {
     override def kind: Kind = Kind.Unknown
     override def isRemote: Boolean = true
     override def isEmpty: Boolean = false
+    override def isFinished: Boolean = false
     override def position(): Position = Position.Unknown
     override def tag(key: String, value: String): Span = this
     override def tag(key: String, value: Long): Span = this