[#374] Add inner-ring event metrics

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

pkg/innerring/processors/balance/processor.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/innerring/metrics"
 	frostfscontract "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/morph/client/frostfs"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/morph/event"
 	balanceEvent "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/morph/event/balance"
@@ -32,6 +33,7 @@ type (
 	// Processor of events produced by balance contract in the morphchain.
 	Processor struct {
 		log           *logger.Logger
+		metrics       metrics.Register
 		pool          *ants.Pool
 		frostfsClient FrostFSClient
 		balanceSC     util.Uint160
@@ -42,6 +44,7 @@ type (
 	// Params of the processor constructor.
 	Params struct {
 		Log           *logger.Logger
+		Metrics       metrics.Register
 		PoolSize      int
 		FrostFSClient FrostFSClient
 		BalanceSC     util.Uint160
@@ -72,8 +75,14 @@ func New(p *Params) (*Processor, error) {
 		return nil, fmt.Errorf("ir/balance: can't create worker pool: %w", err)
 	}
 
+	metricsRegister := p.Metrics
+	if metricsRegister == nil {
+		metricsRegister = metrics.DefaultRegister{}
+	}
+
 	return &Processor{
 		log:           p.Log,
+		metrics:       metricsRegister,
 		pool:          pool,
 		frostfsClient: p.FrostFSClient,
 		balanceSC:     p.BalanceSC,