perf: reduce unnecessary allocations in NewSHA1 and NewMD5

hash.go

@@ -28,32 +28,42 @@ var (
 // NewHash returns a new UUID derived from the hash of space concatenated with
 // data generated by h.  The hash should be at least 16 byte in length.  The
 // first 16 bytes of the hash are used to form the UUID.  The version of the
-// UUID will be the lower 4 bits of version.  NewHash is used to implement
-// NewMD5 and NewSHA1.
+// UUID will be the lower 4 bits of version.
 func NewHash(h hash.Hash, space UUID, data []byte, version int) UUID {
 	h.Reset()
 	h.Write(space[:]) //nolint:errcheck
 	h.Write(data)     //nolint:errcheck
 	s := h.Sum(nil)
-	var uuid UUID
-	copy(uuid[:], s)
-	uuid[6] = (uuid[6] & 0x0f) | uint8((version&0xf)<<4)
-	uuid[8] = (uuid[8] & 0x3f) | 0x80 // RFC 9562 variant
-	return uuid
+	return fromHash(s, version)
 }
 
 // NewMD5 returns a new MD5 (Version 3) UUID based on the
-// supplied name space and data.  It is the same as calling:
-//
-//  NewHash(md5.New(), space, data, 3)
+// supplied name space and data.
 func NewMD5(space UUID, data []byte) UUID {
-	return NewHash(md5.New(), space, data, 3)
+	h := md5.New()
+	h.Write(space[:]) //nolint:errcheck
+	h.Write(data)     //nolint:errcheck
+	s := h.Sum(make([]byte, 0, md5.Size))
+	return fromHash(s, 3)
 }
 
 // NewSHA1 returns a new SHA1 (Version 5) UUID based on the
-// supplied name space and data.  It is the same as calling:
-//
-//  NewHash(sha1.New(), space, data, 5)
+// supplied name space and data.
 func NewSHA1(space UUID, data []byte) UUID {
-	return NewHash(sha1.New(), space, data, 5)
+	h := sha1.New()
+	h.Write(space[:]) //nolint:errcheck
+	h.Write(data)     //nolint:errcheck
+	s := h.Sum(make([]byte, 0, sha1.Size))
+	return fromHash(s, 5)
+}
+
+// fromHash creates a new UUID from a byte slice.
+// Slice should be at least 16 byte in length.
+// The first 16 bytes of the hash are used to form the UUID.
+// The version of the UUID will be the lower 4 bits of version.
+func fromHash(s []byte, version int) (uuid UUID) {
+	copy(uuid[:], s)
+	uuid[6] = (uuid[6] & 0x0f) | uint8((version&0xf)<<4)
+	uuid[8] = (uuid[8] & 0x3f) | 0x80 // RFC 4122 variant
+	return uuid
 }

uuid_test.go

@@ -414,6 +414,12 @@ func TestMD5(t *testing.T) {
 	}
 }
 
+func BenchmarkMD5(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_ = NewMD5(NameSpaceDNS, []byte("python.org"))
+	}
+}
+
 func TestSHA1(t *testing.T) {
 	uuid := NewSHA1(NameSpaceDNS, []byte("python.org")).String()
 	want := "886313e1-3b8a-5372-9b90-0c9aee199e5d"
@@ -422,6 +428,12 @@ func TestSHA1(t *testing.T) {
 	}
 }
 
+func BenchmarkSHA1(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_ = NewSHA1(NameSpaceDNS, []byte("python.org"))
+	}
+}
+
 func TestNodeID(t *testing.T) {
 	nid := []byte{1, 2, 3, 4, 5, 6}
 	SetNodeInterface("")