internal/telemetry: remove Flush method from exporter

It is never invoked anyway, and it provices no useful benefit while complicating
the implementation, as it is the only non context aware method.

Change-Id: Id5a99439fedafdf4d71285e36103b4854cf3635a
Reviewed-on: https://go-review.googlesource.com/c/tools/+/221540
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>

internal/lsp/debug/serve.go

@@ -49,7 +49,7 @@ type Instance struct {
 
 	LogWriter io.Writer
 
-	ocagent    export.Exporter
+	ocagent    *ocagent.Exporter
 	prometheus *prometheus.Exporter
 	rpcs       *rpcs
 	traces     *traces
@@ -540,12 +540,6 @@ func (i *Instance) Metric(ctx context.Context, data telemetry.MetricData) {
 	}
 }
 
-func (i *Instance) Flush() {
-	if i.ocagent != nil {
-		i.ocagent.Flush()
-	}
-}
-
 type dataFunc func(*http.Request) interface{}
 
 func render(tmpl *template.Template, fun dataFunc) func(http.ResponseWriter, *http.Request) {

internal/telemetry/export/export.go

@@ -26,8 +26,6 @@ type Exporter interface {
 	Log(context.Context, telemetry.Event)
 
 	Metric(context.Context, telemetry.MetricData)
-
-	Flush()
 }
 
 var (
@@ -107,12 +105,3 @@ func Metric(ctx context.Context, data telemetry.MetricData) {
 	}
 	exporter.Metric(ctx, data)
 }
-
-func Flush() {
-	exporterMu.Lock()
-	defer exporterMu.Unlock()
-	if exporter == nil {
-		return
-	}
-	exporter.Flush()
-}

internal/telemetry/export/log.go

@@ -34,4 +34,3 @@ 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/ocagent/ocagent.go

@@ -19,7 +19,6 @@ import (
 	"time"
 
 	"golang.org/x/tools/internal/telemetry"
-	"golang.org/x/tools/internal/telemetry/export"
 	"golang.org/x/tools/internal/telemetry/export/ocagent/wire"
 	"golang.org/x/tools/internal/telemetry/tag"
 )
@@ -43,7 +42,7 @@ func Discover() *Config {
 	}
 }
 
-type exporter struct {
+type Exporter struct {
 	mu      sync.Mutex
 	config  Config
 	spans   []*telemetry.Span
@@ -53,11 +52,11 @@ type exporter struct {
 // Connect creates a process specific exporter with the specified
 // serviceName and the address of the ocagent to which it will upload
 // its telemetry.
-func Connect(config *Config) export.Exporter {
+func Connect(config *Config) *Exporter {
 	if config == nil || config.Address == "off" {
 		return nil
 	}
-	exporter := &exporter{config: *config}
+	exporter := &Exporter{config: *config}
 	if exporter.config.Start.IsZero() {
 		exporter.config.Start = time.Now()
 	}
@@ -85,23 +84,23 @@ func Connect(config *Config) export.Exporter {
 	return exporter
 }
 
-func (e *exporter) StartSpan(ctx context.Context, span *telemetry.Span) {}
+func (e *Exporter) StartSpan(ctx context.Context, span *telemetry.Span) {}
 
-func (e *exporter) FinishSpan(ctx context.Context, span *telemetry.Span) {
+func (e *Exporter) FinishSpan(ctx context.Context, span *telemetry.Span) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 	e.spans = append(e.spans, span)
 }
 
-func (e *exporter) Log(context.Context, telemetry.Event) {}
+func (e *Exporter) Log(context.Context, telemetry.Event) {}
 
-func (e *exporter) Metric(ctx context.Context, data telemetry.MetricData) {
+func (e *Exporter) Metric(ctx context.Context, data telemetry.MetricData) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 	e.metrics = append(e.metrics, data)
 }
 
-func (e *exporter) Flush() {
+func (e *Exporter) Flush() {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 	spans := make([]*wire.Span, len(e.spans))
@@ -149,7 +148,7 @@ func (cfg *Config) buildNode() *wire.Node {
 	}
 }
 
-func (e *exporter) send(endpoint string, message interface{}) {
+func (e *Exporter) send(endpoint string, message interface{}) {
 	blob, err := json.Marshal(message)
 	if err != nil {
 		errorInExport("ocagent failed to marshal message for %v: %v", endpoint, err)

internal/telemetry/export/ocagent/ocagent_test.go

@@ -17,13 +17,12 @@ import (
 	"time"
 
 	"golang.org/x/tools/internal/telemetry"
-	"golang.org/x/tools/internal/telemetry/export"
 	"golang.org/x/tools/internal/telemetry/export/ocagent"
 	"golang.org/x/tools/internal/telemetry/tag"
 )
 
 var (
-	exporter export.Exporter
+	exporter *ocagent.Exporter
 	sent     fakeSender
 	start    time.Time
 	at       time.Time