refactor(node): simplify bee shutdown repetitive io.Closer procedure (#1808)

pkg/node/node.go

@@ -67,6 +67,7 @@ import (
 	"github.com/ethersphere/bee/pkg/topology/lightnode"
 	"github.com/ethersphere/bee/pkg/tracing"
 	"github.com/ethersphere/bee/pkg/traversal"
+	"github.com/hashicorp/go-multierror"
 	ma "github.com/multiformats/go-multiaddr"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/sync/errgroup"
@@ -682,14 +683,21 @@ func NewBee(addr string, swarmAddress swarm.Address, publicKey ecdsa.PublicKey,
 }
 
 func (b *Bee) Shutdown(ctx context.Context) error {
-	errs := new(multiError)
+	var mErr error
 
-	if b.apiCloser != nil {
-		if err := b.apiCloser.Close(); err != nil {
-			errs.add(fmt.Errorf("api: %w", err))
+	// tryClose is a convenient closure which decrease
+	// repetitive io.Closer tryClose procedure.
+	tryClose := func(c io.Closer, errMsg string) {
+		if c == nil {
+			return
+		}
+		if err := c.Close(); err != nil {
+			mErr = multierror.Append(mErr, fmt.Errorf("%s: %w", errMsg, err))
 		}
 	}
 
+	tryClose(b.apiCloser, "api")
+
 	var eg errgroup.Group
 	if b.apiServer != nil {
 		eg.Go(func() error {
@@ -709,113 +717,37 @@ func (b *Bee) Shutdown(ctx context.Context) error {
 	}
 
 	if err := eg.Wait(); err != nil {
-		errs.add(err)
+		mErr = multierror.Append(mErr, err)
 	}
 
 	if b.recoveryHandleCleanup != nil {
 		b.recoveryHandleCleanup()
 	}
 
-	if err := b.pusherCloser.Close(); err != nil {
-		errs.add(fmt.Errorf("pusher: %w", err))
-	}
-
-	if err := b.pullerCloser.Close(); err != nil {
-		errs.add(fmt.Errorf("puller: %w", err))
-	}
-
-	if err := b.pullSyncCloser.Close(); err != nil {
-		errs.add(fmt.Errorf("pull sync: %w", err))
-	}
-
-	if err := b.pssCloser.Close(); err != nil {
-		errs.add(fmt.Errorf("pss: %w", err))
-	}
+	tryClose(b.pusherCloser, "pusher")
+	tryClose(b.pullerCloser, "puller")
+	tryClose(b.pullSyncCloser, "pull sync")
+	tryClose(b.pssCloser, "pss")
 
 	b.p2pCancel()
-	if err := b.p2pService.Close(); err != nil {
-		errs.add(fmt.Errorf("p2p server: %w", err))
-	}
-
-	if b.transactionMonitorCloser != nil {
-		if err := b.transactionMonitorCloser.Close(); err != nil {
-			errs.add(fmt.Errorf("transaction monitor: %w", err))
-		}
-	}
+	tryClose(b.p2pService, "p2p server")
+	tryClose(b.transactionMonitorCloser, "transaction monitor")
 
 	if c := b.ethClientCloser; c != nil {
 		c()
 	}
 
-	if err := b.tracerCloser.Close(); err != nil {
-		errs.add(fmt.Errorf("tracer: %w", err))
-	}
-
-	if err := b.tagsCloser.Close(); err != nil {
-		errs.add(fmt.Errorf("tag persistence: %w", err))
-	}
-
-	if b.listenerCloser != nil {
-		if err := b.listenerCloser.Close(); err != nil {
-			errs.add(fmt.Errorf("listener: %w", err))
-		}
-	}
-
-	if err := b.postageServiceCloser.Close(); err != nil {
-		errs.add(fmt.Errorf("postage service: %w", err))
-	}
-
-	if err := b.stateStoreCloser.Close(); err != nil {
-		errs.add(fmt.Errorf("statestore: %w", err))
-	}
-
-	if err := b.localstoreCloser.Close(); err != nil {
-		errs.add(fmt.Errorf("localstore: %w", err))
-	}
-
-	if err := b.topologyCloser.Close(); err != nil {
-		errs.add(fmt.Errorf("topology driver: %w", err))
-	}
-
-	if err := b.errorLogWriter.Close(); err != nil {
-		errs.add(fmt.Errorf("error log writer: %w", err))
-	}
-
-	// Shutdown the resolver service only if it has been initialized.
-	if b.resolverCloser != nil {
-		if err := b.resolverCloser.Close(); err != nil {
-			errs.add(fmt.Errorf("resolver service: %w", err))
-		}
-	}
-
-	if errs.hasErrors() {
-		return errs
-	}
-
-	return nil
-}
-
-type multiError struct {
-	errors []error
-}
-
-func (e *multiError) Error() string {
-	if len(e.errors) == 0 {
-		return ""
-	}
-	s := e.errors[0].Error()
-	for _, err := range e.errors[1:] {
-		s += "; " + err.Error()
-	}
-	return s
-}
-
-func (e *multiError) add(err error) {
-	e.errors = append(e.errors, err)
-}
+	tryClose(b.tracerCloser, "tracer")
+	tryClose(b.tagsCloser, "tag persistence")
+	tryClose(b.listenerCloser, "listener")
+	tryClose(b.postageServiceCloser, "postage service")
+	tryClose(b.stateStoreCloser, "statestore")
+	tryClose(b.localstoreCloser, "localstore")
+	tryClose(b.topologyCloser, "topology driver")
+	tryClose(b.errorLogWriter, "error log writer")
+	tryClose(b.resolverCloser, "resolver service")
 
-func (e *multiError) hasErrors() bool {
-	return len(e.errors) > 0
+	return mErr
 }
 
 func getTxHash(stateStore storage.StateStorer, logger logging.Logger, o Options) ([]byte, error) {