[#86] Add alphabet contract processor

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/innerring/processors/alphabet/handlers.go

@@ -0,0 +1,21 @@
+package alphabet
+
+import (
+	"github.com/nspcc-dev/neofs-node/pkg/innerring/timers"
+	"github.com/nspcc-dev/neofs-node/pkg/morph/event"
+	"go.uber.org/zap"
+)
+
+func (np *Processor) handleGasEmission(ev event.Event) {
+	_ = ev.(timers.NewAlphabetEmitTick)
+	np.log.Info("tick", zap.String("type", "alphabet gas emit"))
+
+	// send event to the worker pool
+
+	err := np.pool.Submit(func() { np.processEmit() })
+	if err != nil {
+		// there system can be moved into controlled degradation stage
+		np.log.Warn("alphabet processor worker pool drained",
+			zap.Int("capacity", np.pool.Cap()))
+	}
+}