Trace sempahore acquire (#190)

* elasticapm: create span in semAcquire

* otlp: trace semaphore acquire across consumers

input/elasticapm/processor.go

@@ -393,6 +393,9 @@ func (p *Processor) getStreamReader(r io.Reader) *streamReader {
 }
 
 func (p *Processor) semAcquire(ctx context.Context, async bool) error {
+	sp, ctx := apm.StartSpan(ctx, "Semaphore.Acquire", "Reporter")
+	defer sp.End()
+
 	if async {
 		if ok := p.sem.TryAcquire(1); !ok {
 			return ErrQueueFull

input/otlp/logs.go

@@ -63,7 +63,7 @@ func (c *Consumer) ConsumeLogs(ctx context.Context, logs plog.Logs) error {
 // ConsumeLogsWithResult consumes OpenTelemetry log data, converting into
 // the Elastic APM log model and sending to the reporter.
 func (c *Consumer) ConsumeLogsWithResult(ctx context.Context, logs plog.Logs) (ConsumeLogsResult, error) {
-	if err := c.sem.Acquire(ctx, 1); err != nil {
+	if err := semAcquire(ctx, c.sem, 1); err != nil {
 		return ConsumeLogsResult{}, err
 	}
 	defer c.sem.Release(1)

input/otlp/metrics.go

@@ -66,7 +66,7 @@ func (c *Consumer) ConsumeMetrics(ctx context.Context, metrics pmetric.Metrics)
 func (c *Consumer) ConsumeMetricsWithResult(ctx context.Context, metrics pmetric.Metrics) (ConsumeMetricsResult, error) {
 	totalDataPoints := int64(metrics.DataPointCount())
 	totalMetrics := int64(metrics.MetricCount())
-	if err := c.sem.Acquire(ctx, 1); err != nil {
+	if err := semAcquire(ctx, c.sem, 1); err != nil {
 		return ConsumeMetricsResult{}, err
 	}
 	defer c.sem.Release(1)

input/otlp/trace-semaphore.go

@@ -0,0 +1,33 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package otlp
+
+import (
+	"context"
+
+	"go.elastic.co/apm/v2"
+
+	"github.com/elastic/apm-data/input"
+)
+
+func semAcquire(ctx context.Context, sem input.Semaphore, i int64) error {
+	sp, ctx := apm.StartSpan(ctx, "Semaphore.Acquire", "Reporter")
+	defer sp.End()
+
+	return sem.Acquire(ctx, i)
+}

input/otlp/traces.go

@@ -94,7 +94,7 @@ func (c *Consumer) ConsumeTraces(ctx context.Context, traces ptrace.Traces) erro
 // ConsumeTracesWithResult consumes OpenTelemetry trace data,
 // converting into Elastic APM events and reporting to the Elastic APM schema.
 func (c *Consumer) ConsumeTracesWithResult(ctx context.Context, traces ptrace.Traces) (ConsumeTracesResult, error) {
-	if err := c.sem.Acquire(ctx, 1); err != nil {
+	if err := semAcquire(ctx, c.sem, 1); err != nil {
 		return ConsumeTracesResult{}, err
 	}
 	defer c.sem.Release(1)