feat(otel): Add wait metrics to otel (#3493)

* Add wait metrics to otel

* add unit

Author: mwhooker

extra/redisotel/metrics.go

@@ -155,6 +155,23 @@ func reportPoolStats(rdb *redis.Client, conf *config) (metric.Registration, erro
 		return nil, err
 	}
 
+	waits, err := conf.meter.Int64ObservableUpDownCounter(
+		"db.client.connections.waits",
+		metric.WithDescription("The number of times a connection was waited for"),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	waitsDuration, err := conf.meter.Int64ObservableUpDownCounter(
+		"db.client.connections.waits_duration",
+		metric.WithDescription("The total time spent for waiting a connection in nanoseconds"),
+		metric.WithUnit("ns"),
+	)
+	if err != nil {
+		return nil, err
+	}
+
 	timeouts, err := conf.meter.Int64ObservableUpDownCounter(
 		"db.client.connections.timeouts",
 		metric.WithDescription("The number of connection timeouts that have occurred trying to obtain a connection from the pool"),
@@ -191,6 +208,9 @@ func reportPoolStats(rdb *redis.Client, conf *config) (metric.Registration, erro
 			o.ObserveInt64(usage, int64(stats.IdleConns), metric.WithAttributeSet(idleAttrs))
 			o.ObserveInt64(usage, int64(stats.TotalConns-stats.IdleConns), metric.WithAttributeSet(usedAttrs))
 
+			o.ObserveInt64(waits, int64(stats.WaitCount), metric.WithAttributeSet(poolAttrs))
+			o.ObserveInt64(waitsDuration, stats.WaitDurationNs, metric.WithAttributeSet(poolAttrs))
+
 			o.ObserveInt64(timeouts, int64(stats.Timeouts), metric.WithAttributeSet(poolAttrs))
 			o.ObserveInt64(hits, int64(stats.Hits), metric.WithAttributeSet(poolAttrs))
 			o.ObserveInt64(misses, int64(stats.Misses), metric.WithAttributeSet(poolAttrs))