Update header.go

model/flow/header.go

@@ -3,6 +3,7 @@ package flow
 import (
 	"bytes"
 	"encoding/json"
+	"sync"
 	"time"
 
 	"github.com/fxamacker/cbor/v2"
@@ -73,18 +74,17 @@ func (h Header) Fingerprint() []byte {
 	return fingerprint.Fingerprint(h.Body())
 }
 
+var mutex_hdr sync.Mutex
 var previd_hdr Identifier
 var prev_hdr Header
 
 // this does a binary byte-by-byte comparison of identifiers
 // an Identifier is just a 32-byte array
 func compareIdentifiers(a Identifier, b Identifier) int {
-	for i := 0; i < 32; i++ {
-		if a[i] != b[i] {
-			return -1
-		}
+	if a == b {
+		return 0
 	}
-	return 0
+	return -1
 }
 
 // ID returns a unique ID to singularly identify the header and its block
@@ -96,6 +96,11 @@ func (h Header) ID() Identifier {
 		h.Timestamp = h.Timestamp.UTC()
 	}
 
+	// guarantee serialized access
+	mutex_hdr.Lock()
+
+	defer mutex_hdr.Unlock()
+
 	for {
 		// compare these elements individually
 		if prev_hdr.ParentVoterIDs == nil ||
@@ -109,8 +114,7 @@ func (h Header) ID() Identifier {
 		bNotEqual := false
 		if len(h.ParentVoterIDs) > 0 {
 			for i, v := range h.ParentVoterIDs {
-				if len(prev_hdr.ParentVoterIDs) >= i &&
-					compareIdentifiers(v, prev_hdr.ParentVoterIDs[i]) != 0 {
+				if compareIdentifiers(v, prev_hdr.ParentVoterIDs[i]) != 0 {
 					bNotEqual = true
 					break
 				}