lib/protoparser/graphite: fix parsing of a Graphite line with empty tags such as foo; 1 2

See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1100

docs/CHANGELOG.md

@@ -30,6 +30,7 @@
 * BUGFIX: fix `http: superfluous response.WriteHeader call` issue. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1078
 * BUGFIX: fix arm64 builds due to the issue in `github.com/golang/snappy`. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1074
 * BUGFIX: fix `index out of range [1024819115206086200] with length 27` panic, which could occur when `1e-9` value is passed to VictoriaMetrics histogram. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1096
+* BUGFIX: fix parsing for Graphite line with empty tags such as `foo; 123 456`. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1100
 
 
 # [v1.54.1](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.54.1)

lib/protoparser/graphite/parser.go

@@ -71,7 +71,7 @@ func (r *Row) UnmarshalMetricAndTags(s string, tagsPool []Tag) ([]Tag, error) {
 		var err error
 		tagsPool, err = unmarshalTags(tagsPool, s[n+1:])
 		if err != nil {
-			return tagsPool, fmt.Errorf("cannot umarshal tags: %w", err)
+			return tagsPool, fmt.Errorf("cannot unmarshal tags: %w", err)
 		}
 		tags := tagsPool[tagsStart:]
 		r.Tags = tags[:len(tags):len(tags)]
@@ -171,18 +171,14 @@ func unmarshalTags(dst []Tag, s string) ([]Tag, error) {
 		n := strings.IndexByte(s, ';')
 		if n < 0 {
 			// The last tag found
-			if err := tag.unmarshal(s); err != nil {
+			tag.unmarshal(s)
-				return dst[:len(dst)-1], err
-			}
 			if len(tag.Key) == 0 || len(tag.Value) == 0 {
 				// Skip empty tag
 				dst = dst[:len(dst)-1]
 			}
 			return dst, nil
 		}
-		if err := tag.unmarshal(s[:n]); err != nil {
+		tag.unmarshal(s[:n])
-			return dst[:len(dst)-1], err
-		}
 		s = s[n+1:]
 		if len(tag.Key) == 0 || len(tag.Value) == 0 {
 			// Skip empty tag
@@ -202,13 +198,16 @@ func (t *Tag) reset() {
 	t.Value = ""
 }
 
-func (t *Tag) unmarshal(s string) error {
+func (t *Tag) unmarshal(s string) {
 	t.reset()
 	n := strings.IndexByte(s, '=')
 	if n < 0 {
-		return fmt.Errorf("missing tag value for %q", s)
+		// Empty tag value.
+		// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1100
+		t.Key = s
+		t.Value = s[len(s):]
+	} else {
+		t.Key = s[:n]
+		t.Value = s[n+1:]
 	}
-	t.Key = s[:n]
-	t.Value = s[n+1:]
-	return nil
 }

lib/protoparser/graphite/parser_test.go

@@ -19,7 +19,6 @@ func TestUnmarshalMetricAndTagsFailure(t *testing.T) {
 	f("")
 	f(";foo=bar")
 	f(" ")
-	f("foo;bar")
 	f("foo ;bar=baz")
 	f("f oo;bar=baz")
 	f("foo;bar=baz   ")
@@ -80,12 +79,6 @@ func TestRowsUnmarshalFailure(t *testing.T) {
 	// Missing value
 	f("aaa")
 
-	// missing tag
-	f("aa; 12 34")
-
-	// missing tag value
-	f("aa;bb 23 34")
-
 	// unexpected space in tag value
 	// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/99
 	f("s;tag1=aaa1;tag2=bb b2;tag3=ccc3 1")
@@ -187,6 +180,31 @@ func TestRowsUnmarshalSuccess(t *testing.T) {
 		}},
 	})
 	// Empty tags
+	// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1100
+	f("foo; 1", &Rows{
+		Rows: []Row{{
+			Metric: "foo",
+			Tags:   []Tag{},
+			Value:  1,
+		}},
+	})
+	f("foo; 1 2", &Rows{
+		Rows: []Row{{
+			Metric:    "foo",
+			Tags:      []Tag{},
+			Value:     1,
+			Timestamp: 2,
+		}},
+	})
+	// Empty tag name or value
+	f("foo;bar 1 2", &Rows{
+		Rows: []Row{{
+			Metric:    "foo",
+			Tags:      []Tag{},
+			Value:     1,
+			Timestamp: 2,
+		}},
+	})
 	f("foo;bar=baz;aa=;x=y;=z 1 2", &Rows{
 		Rows: []Row{{
 			Metric: "foo",