[#3] signature: Sign parts in parallel

Sign request/response parts in parallel

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

go.mod

@@ -17,6 +17,7 @@ require (
 	github.com/mr-tron/base58 v1.2.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	golang.org/x/net v0.0.0-20201021035429-f5854403a974 // indirect
+	golang.org/x/sync v0.1.0 // indirect
 	golang.org/x/sys v0.1.0 // indirect
 	golang.org/x/text v0.3.3 // indirect
 	google.golang.org/genproto v0.0.0-20200526211855-cb27e3aa2013 // indirect

go.sum

@@ -84,6 +84,8 @@ golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
+golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

signature/sign.go

@@ -7,6 +7,7 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/refs"
 	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/session"
 	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/util/signature"
+	"golang.org/x/sync/errgroup"
 )
 
 type serviceRequest interface {
@@ -68,23 +69,33 @@ func signServiceResponse(key *ecdsa.PrivateKey, v serviceResponse) error {
 }
 
 func signMessageParts(key *ecdsa.PrivateKey, body, meta, header stableMarshaler, hasHeader bool, result signatureReceiver) error {
+	eg := &errgroup.Group{}
 	if !hasHeader {
 		// sign session message body
-		if err := signServiceMessagePart(key, body, result.SetBodySignature); err != nil {
+		eg.Go(func() error {
-			return fmt.Errorf("could not sign body: %w", err)
+			if err := signServiceMessagePart(key, body, result.SetBodySignature); err != nil {
-		}
+				return fmt.Errorf("could not sign body: %w", err)
+			}
+			return nil
+		})
 	}
 
 	// sign meta header
-	if err := signServiceMessagePart(key, meta, result.SetMetaSignature); err != nil {
+	eg.Go(func() error {
-		return fmt.Errorf("could not sign meta header: %w", err)
+		if err := signServiceMessagePart(key, meta, result.SetMetaSignature); err != nil {
-	}
+			return fmt.Errorf("could not sign meta header: %w", err)
+		}
+		return nil
+	})
 
 	// sign verification header origin
-	if err := signServiceMessagePart(key, header, result.SetOriginSignature); err != nil {
+	eg.Go(func() error {
-		return fmt.Errorf("could not sign origin of verification header: %w", err)
+		if err := signServiceMessagePart(key, header, result.SetOriginSignature); err != nil {
-	}
+			return fmt.Errorf("could not sign origin of verification header: %w", err)
-	return nil
+		}
+		return nil
+	})
+	return eg.Wait()
 }
 
 func signServiceMessagePart(key *ecdsa.PrivateKey, part stableMarshaler, sigWrite func(*refs.Signature)) error {