Detecting large refinery events

refinery.diff

diff --git a/route/route.go b/route/route.go
index d0f7ee8..0a92708 100644
--- a/route/route.go
+++ b/route/route.go
@@ -396,6 +396,29 @@ func (r *Router) processEvent(ev *types.Event, reqID interface{}) error {
                WithField("request_id", reqID).
                WithString("api_host", ev.APIHost).
                WithString("dataset", ev.Dataset)
+       var err error
+
+       jsonString, err := json.Marshal(ev.Data)
+       if err == nil {
+               dataSizeBytes := len(jsonString)
+               // Log some data about large events so that we can diagnose where they
+               // are coming from.
+               if dataSizeBytes > 50000 {
+                       log := r.iopLogger.Error()
+                       var serviceName string
+                       var spanName string
+
+                       if svcName, ok := ev.Data["service.name"]; ok {
+                               serviceName = svcName.(string)
+                       }
+                       if spnName, ok := ev.Data["name"]; ok {
+                               spanName = spnName.(string)
+                       }
+                       log.WithString("service_name", serviceName).
+                               WithString("span_name", spanName).
+                               Logf("large event detected")
+               }
+       }

        // extract trace ID, route to self or peer, pass on to collector
        // TODO make trace ID field configurable
@@ -432,7 +455,6 @@ func (r *Router) processEvent(ev *types.Event, reqID interface{}) error {
        }

        // we're supposed to handle it
-       var err error
        span := &types.Span{
                Event:   *ev,
                TraceID: traceID,