complete automatic trace token propagation for spray-client, closes #14

3 files changed, 93 insertions, 29 deletions

diff --git a/kamon-spray/src/main/resources/reference.conf b/kamon-spray/src/main/resources/reference.conf
index 88bd8fb8..67d191c7 100644
--- a/kamon-spray/src/main/resources/reference.conf
+++ b/kamon-spray/src/main/resources/reference.conf
@@ -1,6 +1,31 @@
 kamon {
   spray {
-    include-trace-token-header = true
+    # Header name used when propagating the `TraceContext.token` value across applications.
     trace-token-header-name = "X-Trace-Token"
+
+    # When set to true, Kamon will automatically set and propogate the `TraceContext.token` value under the following
+    # conditions:
+    #  - When a server side request is received containing the trace token header, the new `TraceContext` will have that
+    #    some token, and once the response to that request is ready, the trace token header is also included in the
+    #    response.
+    #  - When a spray-client request is issued and a `TraceContext` is available, the trace token header will be included
+    #    in the `HttpRequest` headers.
+    automatic-trace-token-propagation = true
+
+
+    client {
+      # Strategy used for automatic trace segment generation when issue requests with spray-client. The possible values
+      # are:
+      #  - pipelining: measures the time during which the user application code is waiting for a spray-client request to
+      #    complete, by attaching a callback to the Future[HttpResponse] returned by `spray.client.pipelining.sendReceive`.
+      #    If `spray.client.pipelining.sendReceive` is not used, the segment measurement wont be performed.
+      #  - internal: measures the internal time taken by spray-client to finish a request. Sometimes the user application
+      #    code has a finite future timeout (like when using `spray.client.pipelining.sendReceive`) that doesn't match
+      #    the actual amount of time spray might take internally to resolve a request, counting retries, redirects,
+      #    connection timeouts and so on. If using the internal strategy, the measured time will include the entire time
+      #    since the request has been received by the corresponding `HttpHostConnector` until a response is sent back
+      #    to the requester.
+      segment-collection-strategy = pipelining
+    }
   }
 }
\ No newline at end of file
diff --git a/kamon-spray/src/main/scala/kamon/spray/Spray.scala b/kamon-spray/src/main/scala/kamon/spray/Spray.scala
index 4dc98d85..9de1882a 100644
--- a/kamon-spray/src/main/scala/kamon/spray/Spray.scala
+++ b/kamon-spray/src/main/scala/kamon/spray/Spray.scala
@@ -24,14 +24,29 @@ import spray.http.HttpRequest
 object Spray extends ExtensionId[SprayExtension] with ExtensionIdProvider {
   def lookup(): ExtensionId[_ <: actor.Extension] = Spray
   def createExtension(system: ExtendedActorSystem): SprayExtension = new SprayExtension(system)
+
+}
+
+object ClientSegmentCollectionStrategy {
+  sealed trait Strategy
+  case object Pipelining extends Strategy
+  case object Internal extends Strategy
 }
 
 class SprayExtension(private val system: ExtendedActorSystem) extends Kamon.Extension {
   private val config = system.settings.config.getConfig("kamon.spray")
 
-  val includeTraceToken: Boolean = config.getBoolean("include-trace-token-header")
+  val includeTraceToken: Boolean = config.getBoolean("automatic-trace-token-propagation")
   val traceTokenHeaderName: String = config.getString("trace-token-header-name")
 
+  val clientSegmentCollectionStrategy: ClientSegmentCollectionStrategy.Strategy =
+    config.getString("client.segment-collection-strategy") match {
+      case "pipelining" ⇒ ClientSegmentCollectionStrategy.Pipelining
+      case "internal"   ⇒ ClientSegmentCollectionStrategy.Internal
+      case other ⇒ throw new IllegalArgumentException(s"Configured segment-collection-strategy [$other] is invalid, " +
+        s"only pipelining and internal are valid options.")
+    }
+
   // Later we should expose a way for the user to customize this.
   def assignHttpClientRequestName(request: HttpRequest): String = request.uri.authority.host.address
 }
diff --git a/kamon-spray/src/main/scala/spray/can/client/ClientRequestInstrumentation.scala b/kamon-spray/src/main/scala/spray/can/client/ClientRequestInstrumentation.scala
index 4e2a352c..d7d9cf09 100644
--- a/kamon-spray/src/main/scala/spray/can/client/ClientRequestInstrumentation.scala
+++ b/kamon-spray/src/main/scala/spray/can/client/ClientRequestInstrumentation.scala
@@ -1,29 +1,29 @@
-/* ===================================================
+/*
+ * =========================================================================================
  * Copyright © 2013 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
+ * 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
+ *   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.
- * ========================================================== */
+ * 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 spray.can.client
 
 import org.aspectj.lang.annotation._
 import org.aspectj.lang.ProceedingJoinPoint
-import spray.http.{ HttpResponse, HttpMessageEnd, HttpRequest }
-import spray.http.HttpHeaders.Host
-import kamon.trace.{ TraceRecorder, SegmentCompletionHandleAware, TraceContextAware }
+import spray.http.{ HttpHeader, HttpResponse, HttpMessageEnd, HttpRequest }
+import spray.http.HttpHeaders.{ RawHeader, Host }
+import kamon.trace.{ TraceRecorder, SegmentCompletionHandleAware }
 import kamon.metrics.TraceMetrics.HttpClientRequest
 import kamon.Kamon
-import kamon.spray.Spray
+import kamon.spray.{ ClientSegmentCollectionStrategy, Spray }
 import akka.actor.ActorRef
 import scala.concurrent.{ Future, ExecutionContext }
 import akka.util.Timeout
@@ -43,14 +43,18 @@ class ClientRequestInstrumentation {
     // The RequestContext will be copied when a request needs to be retried but we are only interested in creating the
     // completion handle the first time we create one.
 
-    // The read to ctx.completionHandle should take care of initializing the aspect timely.
+    // The read to ctx.segmentCompletionHandle should take care of initializing the aspect timely.
     if (ctx.segmentCompletionHandle.isEmpty) {
       TraceRecorder.currentContext.map { traceContext ⇒
-        val requestAttributes = basicRequestAttributes(request)
-        val clientRequestName = Kamon(Spray)(traceContext.system).assignHttpClientRequestName(request)
-        val completionHandle = traceContext.startSegment(HttpClientRequest(clientRequestName, SprayTime), requestAttributes)
+        val sprayExtension = Kamon(Spray)(traceContext.system)
 
-        ctx.segmentCompletionHandle = Some(completionHandle)
+        if (sprayExtension.clientSegmentCollectionStrategy == ClientSegmentCollectionStrategy.Internal) {
+          val requestAttributes = basicRequestAttributes(request)
+          val clientRequestName = sprayExtension.assignHttpClientRequestName(request)
+          val completionHandle = traceContext.startSegment(HttpClientRequest(clientRequestName, SprayTime), requestAttributes)
+
+          ctx.segmentCompletionHandle = Some(completionHandle)
+        }
       }
     }
   }
@@ -92,15 +96,18 @@ class ClientRequestInstrumentation {
 
     (request: HttpRequest) ⇒ {
       val responseFuture = originalSendReceive.apply(request)
-
       TraceRecorder.currentContext.map { traceContext ⇒
-        val requestAttributes = basicRequestAttributes(request)
-        val clientRequestName = Kamon(Spray)(traceContext.system).assignHttpClientRequestName(request)
-        val completionHandle = traceContext.startSegment(HttpClientRequest(clientRequestName, UserTime), requestAttributes)
+        val sprayExtension = Kamon(Spray)(traceContext.system)
 
-        responseFuture.onComplete { result ⇒
-          completionHandle.finish(Map.empty)
-        }(ec)
+        if (sprayExtension.clientSegmentCollectionStrategy == ClientSegmentCollectionStrategy.Pipelining) {
+          val requestAttributes = basicRequestAttributes(request)
+          val clientRequestName = sprayExtension.assignHttpClientRequestName(request)
+          val completionHandle = traceContext.startSegment(HttpClientRequest(clientRequestName, UserTime), requestAttributes)
+
+          responseFuture.onComplete { result ⇒
+            completionHandle.finish(Map.empty)
+          }(ec)
+        }
       }
 
       responseFuture
@@ -114,6 +121,23 @@ class ClientRequestInstrumentation {
       "path" -> request.uri.path.toString(),
       "method" -> request.method.toString())
   }
+
+  @Pointcut("call(* spray.http.HttpMessage.withDefaultHeaders(*)) && within(spray.can.client.HttpHostConnector) && args(defaultHeaders)")
+  def includingDefaultHeadersAtHttpHostConnector(defaultHeaders: List[HttpHeader]): Unit = {}
+
+  @Around("includingDefaultHeadersAtHttpHostConnector(defaultHeaders)")
+  def aroundIncludingDefaultHeadersAtHttpHostConnector(pjp: ProceedingJoinPoint, defaultHeaders: List[HttpHeader]): Any = {
+    val modifiedHeaders = TraceRecorder.currentContext map { traceContext ⇒
+      val sprayExtension = Kamon(Spray)(traceContext.system)
+
+      if (sprayExtension.includeTraceToken)
+        RawHeader(sprayExtension.traceTokenHeaderName, traceContext.token) :: defaultHeaders
+      else
+        defaultHeaders
+    } getOrElse defaultHeaders
+
+    pjp.proceed(Array(modifiedHeaders))
+  }
 }
 
 object ClientRequestInstrumentation {