internal/telemetry: add the ability to flush telemetry data

Change-Id: I5de33edc352a5202fdf9e38538a224dd6adafedb
Reviewed-on: https://go-review.googlesource.com/c/tools/+/190799
Run-TryBot: Ian Cottrell <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Rebecca Stambler <[email protected]>
Reviewed-by: Emmanuel Odeke <[email protected]>

Author: Ian Cottrell

internal/lsp/debug/rpc.go

@@ -93,6 +93,8 @@ type rpcCodeBucket struct {
 func (r *rpcs) StartSpan(ctx context.Context, span *telemetry.Span)  {}
 func (r *rpcs) FinishSpan(ctx context.Context, span *telemetry.Span) {}
 func (r *rpcs) Log(ctx context.Context, event telemetry.Event)       {}
+func (r *rpcs) Flush()                                               {}
+
 func (r *rpcs) Metric(ctx context.Context, data telemetry.MetricData) {
 	for i, group := range data.Groups() {
 		set := &r.Inbound

internal/lsp/debug/trace.go

@@ -134,6 +134,8 @@ func (t *traces) Log(ctx context.Context, event telemetry.Event) {}
 
 func (t *traces) Metric(ctx context.Context, data telemetry.MetricData) {}
 
+func (t *traces) Flush() {}
+
 func (t *traces) getData(req *http.Request) interface{} {
 	if len(t.sets) == 0 {
 		return nil

internal/lsp/protocol/context.go

@@ -27,8 +27,11 @@ func WithClient(ctx context.Context, client Client) context.Context {
 // context.
 type logExporter struct{}
 
-func (logExporter) StartSpan(context.Context, *telemetry.Span)  {}
-func (logExporter) FinishSpan(context.Context, *telemetry.Span) {}
+func (logExporter) StartSpan(context.Context, *telemetry.Span)   {}
+func (logExporter) FinishSpan(context.Context, *telemetry.Span)  {}
+func (logExporter) Metric(context.Context, telemetry.MetricData) {}
+func (logExporter) Flush()                                       {}
+
 func (logExporter) Log(ctx context.Context, event telemetry.Event) {
 	client, ok := ctx.Value(clientKey).(Client)
 	if !ok {
@@ -40,4 +43,3 @@ func (logExporter) Log(ctx context.Context, event telemetry.Event) {
 	}
 	go client.LogMessage(xcontext.Detach(ctx), msg)
 }
-func (logExporter) Metric(context.Context, telemetry.MetricData) {}

internal/telemetry/export/export.go

@@ -26,6 +26,8 @@ type Exporter interface {
 	Log(context.Context, telemetry.Event)
 
 	Metric(context.Context, telemetry.MetricData)
+
+	Flush()
 }
 
 var (
@@ -90,3 +92,9 @@ func Metric(ctx context.Context, data telemetry.MetricData) {
 	defer exporterMu.Unlock()
 	exporter.Metric(ctx, data)
 }
+
+func Flush() {
+	exporterMu.Lock()
+	defer exporterMu.Unlock()
+	exporter.Flush()
+}

internal/telemetry/export/log.go

@@ -35,3 +35,4 @@ func (w *logWriter) Log(ctx context.Context, event telemetry.Event) {
 	fmt.Fprintf(w.writer, "%v\n", event)
 }
 func (w *logWriter) Metric(context.Context, telemetry.MetricData) {}
+func (w *logWriter) Flush()                                       {}

internal/telemetry/export/multi.go

@@ -48,3 +48,8 @@ func (m multi) Metric(ctx context.Context, data telemetry.MetricData) {
 		o.Metric(ctx, data)
 	}
 }
+func (m multi) Flush() {
+	for _, o := range m {
+		o.Flush()
+	}
+}

internal/telemetry/export/null.go

@@ -21,3 +21,4 @@ func (null) StartSpan(context.Context, *telemetry.Span)   {}
 func (null) FinishSpan(context.Context, *telemetry.Span)  {}
 func (null) Log(context.Context, telemetry.Event)         {}
 func (null) Metric(context.Context, telemetry.MetricData) {}
+func (null) Flush()                                       {}

internal/telemetry/export/prometheus/prometheus.go

@@ -28,6 +28,8 @@ type Exporter struct {
 func (e *Exporter) StartSpan(ctx context.Context, span *telemetry.Span)  {}
 func (e *Exporter) FinishSpan(ctx context.Context, span *telemetry.Span) {}
 func (e *Exporter) Log(ctx context.Context, event telemetry.Event)       {}
+func (e *Exporter) Flush()                                               {}
+
 func (e *Exporter) Metric(ctx context.Context, data telemetry.MetricData) {
 	e.mu.Lock()
 	defer e.mu.Unlock()