Cherry-pick #17622 to 7.x: [libbeat] Clarify field name / remove redundant semaphore creation

CHANGELOG-developer.next.asciidoc

@@ -34,6 +34,7 @@ The list below covers the major changes between 7.0.0-rc2 and master only.
 - `queue.Eventer` has been renamed to `queue.ACKListener` {pull}16691[16691]
 - Require logger as first parameter for `outputs.elasticsearch.client#BulkReadItemStatus`. {pull}16761[16761]
 - Extract Elasticsearch client logic from `outputs/elasticsearch` package into new `esclientleg` package. {pull}16150[16150]
+- Rename `queue.BufferConfig.Events` to `queue.BufferConfig.MaxEvents`. {pull}17622[17622]
 
 ==== Bugfixes
 

libbeat/publisher/pipeline/pipeline.go

@@ -183,11 +183,7 @@ func New(
 		return nil, err
 	}
 
-	if count := p.queue.BufferConfig().Events; count > 0 {
-		p.eventSema = newSema(count)
-	}
-
-	maxEvents := p.queue.BufferConfig().Events
+	maxEvents := p.queue.BufferConfig().MaxEvents
 	if maxEvents <= 0 {
 		// Maximum number of events until acker starts blocking.
 		// Only active if pipeline can drop events.

libbeat/publisher/queue/memqueue/broker.go

@@ -191,7 +191,7 @@ func (b *broker) Close() error {
 
 func (b *broker) BufferConfig() queue.BufferConfig {
 	return queue.BufferConfig{
-		Events: b.bufSize,
+		MaxEvents: b.bufSize,
 	}
 }
 

libbeat/publisher/queue/queue.go

@@ -58,7 +58,9 @@ type Queue interface {
 // but still dropping events, the pipeline can use the buffer information,
 // to define an upper bound of events being active in the pipeline.
 type BufferConfig struct {
-	Events int // can be <= 0, if queue can not determine limit
+	// MaxEvents is the maximum number of events the queue can hold at capacity.
+	// A value <= 0 means there is no fixed limit.
+	MaxEvents int
 }
 
 // ProducerConfig as used by the Pipeline to configure some custom callbacks

libbeat/publisher/queue/spool/spool.go

@@ -175,7 +175,7 @@ func (s *diskSpool) Close() error {
 
 // BufferConfig returns the queue initial buffer settings.
 func (s *diskSpool) BufferConfig() queue.BufferConfig {
-	return queue.BufferConfig{Events: -1}
+	return queue.BufferConfig{MaxEvents: -1}
 }
 
 // Producer creates a new queue producer for publishing events.