Remove SuperPool instrumentation.

By definition, a Flow generated by a SuperPool does not respect ordering
of requests and responses, and in fact will typically only rarely actually
behave in the fashion that the instrumentation expects. The previous implementation
would start a span for a given request before submitting it as input to the flow,
and close the span with whatever response is next emitted by the flow. This
request will rarely (if ever) be the actual response for the request that
started the span. For more info, see the official docs at
https://doc.akka.io/docs/akka-http/current/client-side/host-level.html#configuring-a-host-connection-pool

Additionally, compiling this instumentation against scala 2.11, and only
scala 2.11 can (and does) cause significant problems at runtime due to the
fact that Scala is explicitly not binary compatible across major versions.

Author: dpratt

dd-java-agent/instrumentation/akka-http-10.0/src/main/scala/datadog/trace/instrumentation/akkahttp/AkkaHttpClientDecorator.java renamed to dd-java-agent/instrumentation/akka-http-10.0/src/main/java/datadog/trace/instrumentation/akkahttp/AkkaHttpClientDecorator.java

@@ -2,15 +2,12 @@
 
 import static datadog.trace.instrumentation.akkahttp.AkkaHttpClientDecorator.DECORATE;
 import static net.bytebuddy.matcher.ElementMatchers.named;
-import static net.bytebuddy.matcher.ElementMatchers.returns;
 import static net.bytebuddy.matcher.ElementMatchers.takesArgument;
 
-import akka.NotUsed;
 import akka.http.javadsl.model.headers.RawHeader;
 import akka.http.scaladsl.HttpExt;
 import akka.http.scaladsl.model.HttpRequest;
 import akka.http.scaladsl.model.HttpResponse;
-import akka.stream.scaladsl.Flow;
 import com.google.auto.service.AutoService;
 import datadog.trace.agent.tooling.Instrumenter;
 import datadog.trace.bootstrap.CallDepthThreadLocalMap;
@@ -27,7 +24,6 @@
 import net.bytebuddy.description.method.MethodDescription;
 import net.bytebuddy.description.type.TypeDescription;
 import net.bytebuddy.matcher.ElementMatcher;
-import scala.Tuple2;
 import scala.concurrent.Future;
 import scala.runtime.AbstractFunction1;
 import scala.util.Try;
@@ -49,7 +45,6 @@ public String[] helperClassNames() {
     return new String[] {
       AkkaHttpClientInstrumentation.class.getName() + "$OnCompleteHandler",
       AkkaHttpClientInstrumentation.class.getName() + "$AkkaHttpHeaders",
-      packageName + ".AkkaHttpClientTransformFlow",
       "datadog.trace.agent.decorator.BaseDecorator",
       "datadog.trace.agent.decorator.ClientDecorator",
       "datadog.trace.agent.decorator.HttpClientDecorator",
@@ -69,14 +64,6 @@ public Map<? extends ElementMatcher<? super MethodDescription>, String> transfor
         named("singleRequestImpl")
             .and(takesArgument(0, named("akka.http.scaladsl.model.HttpRequest"))),
         SingleRequestAdvice.class.getName());
-    // This is mainly for compatibility with 10.0
-    transformers.put(
-        named("superPool").and(returns(named("akka.stream.scaladsl.Flow"))),
-        SuperPoolAdvice.class.getName());
-    // This is for 10.1+
-    transformers.put(
-        named("superPoolImpl").and(returns(named("akka.stream.scaladsl.Flow"))),
-        SuperPoolAdvice.class.getName());
     return transformers;
   }
 
@@ -105,7 +92,6 @@ public static Scope methodEnter(
         // Request is immutable, so we have to assign new value once we update headers
         request = headers.getRequest();
       }
-
       return scope;
     }
 
@@ -134,34 +120,6 @@ public static void methodExit(
     }
   }
 
-  public static class SuperPoolAdvice {
-
-    @Advice.OnMethodEnter(suppress = Throwable.class)
-    public static boolean methodEnter() {
-      /*
-      Versions 10.0 and 10.1 have slightly different structure that is hard to distinguish so here
-      we cast 'wider net' and avoid instrumenting twice.
-      In the future we may want to separate these, but since lots of code is reused we would need to come up
-      with way of continuing to reusing it.
-       */
-      final int callDepth = CallDepthThreadLocalMap.incrementCallDepth(HttpExt.class);
-      return callDepth <= 0;
-    }
-
-    @Advice.OnMethodExit(suppress = Throwable.class)
-    public static <T> void methodExit(
-        @Advice.Return(readOnly = false)
-            Flow<Tuple2<HttpRequest, T>, Tuple2<Try<HttpResponse>, T>, NotUsed> flow,
-        @Advice.Enter final boolean isApplied) {
-      if (!isApplied) {
-        return;
-      }
-      CallDepthThreadLocalMap.reset(HttpExt.class);
-
-      flow = AkkaHttpClientTransformFlow.transform(flow);
-    }
-  }
-
   public static class OnCompleteHandler extends AbstractFunction1<Try<HttpResponse>, Void> {
     private final Span span;