internal/lsp: rewrite the stats using the newer telemetry features

This allows us to reduce the handler interface and delete the telemetry handler.
It is also safer and faster, and can be easily disabled along with the rest of
the telemetry system.

Change-Id: Ia4961d7f2e374f7dc22360d6a4020a065bfeae6f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/225957
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

1 files changed, 25 insertions, 1 deletions

diff --git a/internal/lsp/debug/rpc.go b/internal/lsp/debug/rpc.go
index 0f39c7cdd..823ee9d43 100644
--- a/internal/lsp/debug/rpc.go
+++ b/internal/lsp/debug/rpc.go
@@ -11,9 +11,11 @@ import (
 	"net/http"
 	"sort"
 	"sync"
+	"time"
 
 	"golang.org/x/tools/internal/lsp/debug/tag"
 	"golang.org/x/tools/internal/telemetry/event"
+	"golang.org/x/tools/internal/telemetry/export"
 	"golang.org/x/tools/internal/telemetry/export/metric"
 )
 
@@ -92,11 +94,33 @@ type rpcCodeBucket struct {
 }
 
 func (r *rpcs) ProcessEvent(ctx context.Context, ev event.Event, tagMap event.TagMap) context.Context {
-	if !ev.IsRecord() {
+	switch {
+	case ev.IsEndSpan():
+		// calculate latency if this was an rpc span
+		span := export.GetSpan(ctx)
+		if span == nil {
+			return ctx
+		}
+		// is this a finished rpc span, if so it will have a status code record
+		for _, ev := range span.Events() {
+			code := tag.StatusCode.Get(ev.Map())
+			if code != "" {
+				elapsedTime := span.Finish().At.Sub(span.Start().At)
+				latencyMillis := float64(elapsedTime) / float64(time.Millisecond)
+				statsCtx := event.Label1(ctx, tag.StatusCode.Of(code))
+				event.Record1(statsCtx, tag.Latency.Of(latencyMillis))
+			}
+		}
+		return ctx
+	case ev.IsRecord():
+		// fall through to the metrics handling logic
+	default:
+		// ignore all other event types
 		return ctx
 	}
 	r.mu.Lock()
 	defer r.mu.Unlock()
+	//TODO(38168): we should just deal with the events here and not use metrics
 	metrics := metric.Entries.Get(tagMap).([]metric.Data)
 	for _, data := range metrics {
 		for i, group := range data.Groups() {