add utilily classes for working with Spans and Continuations

4 files changed, 52 insertions, 2 deletions

diff --git a/kamon-core/src/main/scala/kamon/Kamon.scala b/kamon-core/src/main/scala/kamon/Kamon.scala
index c2ee0b1e..b256cb22 100644
--- a/kamon-core/src/main/scala/kamon/Kamon.scala
+++ b/kamon-core/src/main/scala/kamon/Kamon.scala
@@ -27,6 +27,8 @@ import kamon.util.MeasurementUnit
 import scala.concurrent.Future
 import java.time.Duration
 
+import io.opentracing.ActiveSpan.Continuation
+
 
 object Kamon extends MetricLookup with ReporterRegistry with io.opentracing.Tracer {
   private val initialConfig = ConfigFactory.load()
@@ -78,6 +80,12 @@ object Kamon extends MetricLookup with ReporterRegistry with io.opentracing.Trac
   override def makeActive(span: Span): ActiveSpan =
     kamonTracer.makeActive(span)
 
+  def withActiveSpan[T](continuation: Continuation)(code: => T): T = {
+    val activeSpan = continuation.activate()
+    val evaluatedCode = code
+    activeSpan.deactivate()
+    evaluatedCode
+  }
 
 
   override def loadReportersFromConfig(): Unit =
diff --git a/kamon-core/src/main/scala/kamon/trace/Span.scala b/kamon-core/src/main/scala/kamon/trace/Span.scala
index 583c2b35..04b8eaf3 100644
--- a/kamon-core/src/main/scala/kamon/trace/Span.scala
+++ b/kamon-core/src/main/scala/kamon/trace/Span.scala
@@ -183,4 +183,4 @@ object Span {
     tags: Map[String, String],
     logs: Seq[LogEntry]
   )
-}
+}
\ No newline at end of file
diff --git a/kamon-core/src/main/scala/kamon/trace/Tracer.scala b/kamon-core/src/main/scala/kamon/trace/Tracer.scala
index b4ec936f..3aeb968f 100644
--- a/kamon-core/src/main/scala/kamon/trace/Tracer.scala
+++ b/kamon-core/src/main/scala/kamon/trace/Tracer.scala
@@ -159,5 +159,4 @@ class Tracer(metrics: MetricLookup, reporterRegistry: ReporterRegistryImpl, init
   private final class TracerMetrics(metricLookup: MetricLookup) {
     val createdSpans = metricLookup.counter("tracer.spans-created")
   }
-
 }
diff --git a/kamon-core/src/main/scala/kamon/util/Mixin.scala b/kamon-core/src/main/scala/kamon/util/Mixin.scala
new file mode 100644
index 00000000..f214e875
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/util/Mixin.scala
@@ -0,0 +1,43 @@
+/* =========================================================================================
+ * Copyright © 2013-2017 the kamon project <http://kamon.io/>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+ * either express or implied. See the License for the specific language governing permissions
+ * and limitations under the License.
+ * =========================================================================================
+ */
+
+package kamon
+package util
+
+import io.opentracing.ActiveSpan
+import io.opentracing.ActiveSpan.Continuation
+
+/**
+  *  Utility trait that marks objects carrying an ActiveSpan.Continuation.
+  */
+trait HasContinuation {
+  def continuation: Continuation
+}
+
+object HasContinuation {
+  private class Default(val continuation: Continuation) extends HasContinuation
+
+  /**
+    * Construct a HasContinuation instance by capturing a continuation from the provided active span.
+    */
+  def from(activeSpan: ActiveSpan): HasContinuation =
+    new Default(activeSpan.capture())
+
+  /**
+    * Constructs a new HasContinuation instance using Kamon's tracer currently active span.
+    */
+  def fromTracerActiveSpan(): HasContinuation =
+    new Default(Kamon.activeSpan().capture())
+}