[#374] Add inner-ring event metrics

Signed-off-by: Alejandro Lopez <a.lopez@yadro.com>

pkg/innerring/processors/util.go

@@ -0,0 +1,16 @@
+package processors
+
+import (
+	"time"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/innerring/metrics"
+	"github.com/panjf2000/ants/v2"
+)
+
+func SubmitEvent(pool *ants.Pool, metrics metrics.Register, eventLabel string, eventProcessor func() bool) error {
+	return pool.Submit(func() {
+		start := time.Now()
+		success := eventProcessor()
+		metrics.AddEvent(time.Since(start), eventLabel, success)
+	})
+}