Clean up some service profiler behavior in Conduit futures

Summary:
Correct two minor Conduit future issues:

  - FutureAgent shows up in the trace log as "<mystery>". Since it isn't doing anything useful, solve the mystery and drop it from the log.
  - Simply the ConduitFuture code for interacting with the service profiler now that a more structured integration is available.

Test Plan: Ran "arc branches --trace", saw conduit calls and no more "<mystery>" clutter.

Differential Revision: https://secure.phabricator.com/D21388

src/conduit/ConduitFuture.php

@@ -5,7 +5,6 @@ final class ConduitFuture extends FutureProxy {
   private $client;
   private $engine;
   private $conduitMethod;
-  private $profilerCallID;
 
   public function setClient(ConduitClient $client, $method) {
     $this->client = $client;
@@ -13,29 +12,19 @@ final class ConduitFuture extends FutureProxy {
     return $this;
   }
 
-  public function isReady() {
-    if ($this->profilerCallID === null) {
-      $profiler = PhutilServiceProfiler::getInstance();
-
-      $this->profilerCallID = $profiler->beginServiceCall(
-        array(
+  protected function getServiceProfilerStartParameters() {
+    return array(
       'type' => 'conduit',
       'method' => $this->conduitMethod,
       'size' => $this->getProxiedFuture()->getHTTPRequestByteLength(),
-        ));
+    );
   }
 
-    return parent::isReady();
+  protected function getServiceProfilerResultParameters() {
+    return array();
   }
 
   protected function didReceiveResult($result) {
-    if ($this->profilerCallID !== null) {
-      $profiler = PhutilServiceProfiler::getInstance();
-      $profiler->endServiceCall(
-        $this->profilerCallID,
-        array());
-    }
-
     list($status, $body, $headers) = $result;
     if ($status->isError()) {
       throw $status;

src/conduit/FutureAgent.php

@@ -35,4 +35,11 @@ abstract class FutureAgent
     return $sockets;
   }
 
+  protected function getServiceProfilerStartParameters() {
+    // At least today, the agent construct doesn't add anything interesting
+    // to the trace and the underlying futures always show up in the trace
+    // themselves.
+    return null;
+  }
+
 }

src/future/Future.php

@@ -115,6 +115,10 @@ abstract class Future extends Phobject {
 
     $params = $this->getServiceProfilerStartParameters();
 
+    if ($params === null) {
+      return;
+    }
+
     $profiler = PhutilServiceProfiler::getInstance();
     $call_id = $profiler->beginServiceCall($params);