lib/promrelabel: optimize relabeling performance for common cases

docs/CHANGELOG.md

@@ -11,6 +11,7 @@
   * `process_io_storage_read_bytes_total` - the number of bytes read from storage layer
   * `process_io_storage_written_bytes_total` - the number of bytes written to storage layer
 * FEATURE: vmagent: export `vm_promscrape_target_relabel_duration_seconds` metric, which can be used for monitoring the time spend on relabeling for discovered targets.
+* FEATURE: vmagent: optimize [relabeling](https://victoriametrics.github.io/vmagent.html#relabeling) performance for common cases.
 
 
 * BUGFIX: vmagent: properly perform graceful shutdown on `SIGINT` and `SIGTERM` signals. The graceful shutdown has been broken in `v1.54.0`. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1065

lib/promrelabel/relabel.go

@@ -115,12 +115,23 @@ func applyRelabelConfig(labels []prompbmarshal.Label, labelsOffset int, prc *Par
 	case "replace":
 		bb := relabelBufPool.Get()
 		bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
-		if len(bb.B) == 0 && prc.Regex == defaultRegexForRelabelConfig && !prc.hasCaptureGroupInReplacement && !prc.hasCaptureGroupInTargetLabel {
+		if prc.Regex == defaultRegexForRelabelConfig && !prc.hasCaptureGroupInTargetLabel {
-			// Fast path for the following rule that just sets label value:
+			if prc.Replacement == "$1" {
+				// Fast path for the rule that copies source label values to destination:
+				// - source_labels: [...]
+				//   target_label: foobar
+				valueStr := string(bb.B)
+				relabelBufPool.Put(bb)
+				return setLabelValue(labels, labelsOffset, prc.TargetLabel, valueStr)
+			}
+			if !prc.hasCaptureGroupInReplacement {
+				// Fast path for the rule that sets label value:
 				// - target_label: foobar
 				//   replacement: something-here
 				relabelBufPool.Put(bb)
-			return setLabelValue(labels, labelsOffset, prc.TargetLabel, prc.Replacement)
+				labels = setLabelValue(labels, labelsOffset, prc.TargetLabel, prc.Replacement)
+				return labels
+			}
 		}
 		match := prc.Regex.FindSubmatchIndex(bb.B)
 		if match == nil {
@@ -139,6 +150,13 @@ func applyRelabelConfig(labels []prompbmarshal.Label, labelsOffset int, prc *Par
 	case "replace_all":
 		bb := relabelBufPool.Get()
 		bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
+		if prefix, complete := prc.Regex.LiteralPrefix(); complete && !prc.hasCaptureGroupInReplacement {
+			// Fast path - string replacement without regexp.
+			sourceStr := string(bb.B)
+			relabelBufPool.Put(bb)
+			valueStr := strings.ReplaceAll(sourceStr, prefix, prc.Replacement)
+			return setLabelValue(labels, labelsOffset, prc.TargetLabel, valueStr)
+		}
 		if !prc.Regex.Match(bb.B) {
 			// Fast path - nothing to replace.
 			relabelBufPool.Put(bb)
@@ -175,7 +193,14 @@ func applyRelabelConfig(labels []prompbmarshal.Label, labelsOffset int, prc *Par
 	case "keep":
 		bb := relabelBufPool.Get()
 		bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
-		keep := prc.Regex.Match(bb.B)
+		keep := false
+		if prefix, complete := prc.Regex.LiteralPrefix(); complete {
+			// Fast path - simple string match
+			keep = prefix == string(bb.B)
+		} else {
+			// Slow path - match by regexp
+			keep = prc.Regex.Match(bb.B)
+		}
 		relabelBufPool.Put(bb)
 		if !keep {
 			return labels[:labelsOffset]
@@ -184,7 +209,14 @@ func applyRelabelConfig(labels []prompbmarshal.Label, labelsOffset int, prc *Par
 	case "drop":
 		bb := relabelBufPool.Get()
 		bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
-		drop := prc.Regex.Match(bb.B)
+		drop := false
+		if prefix, complete := prc.Regex.LiteralPrefix(); complete {
+			// Fast path - simple string match
+			drop = prefix == string(bb.B)
+		} else {
+			// Slow path - match by regexp
+			drop = prc.Regex.Match(bb.B)
+		}
 		relabelBufPool.Put(bb)
 		if drop {
 			return labels[:labelsOffset]
@@ -214,16 +246,28 @@ func applyRelabelConfig(labels []prompbmarshal.Label, labelsOffset int, prc *Par
 	case "labelmap_all":
 		for i := range src {
 			label := &src[i]
+			if prefix, complete := prc.Regex.LiteralPrefix(); complete && !prc.hasCaptureGroupInReplacement {
+				// Fast path - replace without regexp
+				label.Name = strings.ReplaceAll(label.Name, prefix, prc.Replacement)
+			} else {
+				// Slow path - replace with regexp.
 				if !prc.Regex.MatchString(label.Name) {
 					continue
 				}
 				label.Name = prc.Regex.ReplaceAllString(label.Name, prc.Replacement)
 			}
+		}
 		return labels
 	case "labeldrop":
 		keepSrc := true
 		for i := range src {
-			if prc.Regex.MatchString(src[i].Name) {
+			label := &src[i]
+			if prefix, complete := prc.Regex.LiteralPrefix(); complete {
+				if prefix == label.Name {
+					keepSrc = false
+					break
+				}
+			} else if prc.Regex.MatchString(label.Name) {
 				keepSrc = false
 				break
 			}
@@ -234,7 +278,11 @@ func applyRelabelConfig(labels []prompbmarshal.Label, labelsOffset int, prc *Par
 		dst := labels[:labelsOffset]
 		for i := range src {
 			label := &src[i]
-			if !prc.Regex.MatchString(label.Name) {
+			if prefix, complete := prc.Regex.LiteralPrefix(); complete {
+				if prefix != label.Name {
+					dst = append(dst, *label)
+				}
+			} else if !prc.Regex.MatchString(label.Name) {
 				dst = append(dst, *label)
 			}
 		}
@@ -242,7 +290,13 @@ func applyRelabelConfig(labels []prompbmarshal.Label, labelsOffset int, prc *Par
 	case "labelkeep":
 		keepSrc := true
 		for i := range src {
-			if !prc.Regex.MatchString(src[i].Name) {
+			label := &src[i]
+			if prefix, complete := prc.Regex.LiteralPrefix(); complete {
+				if prefix != label.Name {
+					keepSrc = false
+					break
+				}
+			} else if !prc.Regex.MatchString(src[i].Name) {
 				keepSrc = false
 				break
 			}
@@ -253,7 +307,11 @@ func applyRelabelConfig(labels []prompbmarshal.Label, labelsOffset int, prc *Par
 		dst := labels[:labelsOffset]
 		for i := range src {
 			label := &src[i]
-			if prc.Regex.MatchString(label.Name) {
+			if prefix, complete := prc.Regex.LiteralPrefix(); complete {
+				if prefix == label.Name {
+					dst = append(dst, *label)
+				}
+			} else if prc.Regex.MatchString(label.Name) {
 				dst = append(dst, *label)
 			}
 		}

lib/promrelabel/relabel_test.go

@@ -232,6 +232,28 @@ func TestApplyRelabelConfigs(t *testing.T) {
 		})
 	})
 	t.Run("replace_all-hit", func(t *testing.T) {
+		f([]ParsedRelabelConfig{
+			{
+				Action:       "replace_all",
+				SourceLabels: []string{"xxx"},
+				Separator:    ";",
+				TargetLabel:  "xxx",
+				Regex:        regexp.MustCompile("-"),
+				Replacement:  ".",
+			},
+		}, []prompbmarshal.Label{
+			{
+				Name:  "xxx",
+				Value: "a-b-c",
+			},
+		}, false, []prompbmarshal.Label{
+			{
+				Name:  "xxx",
+				Value: "a.b.c",
+			},
+		})
+	})
+	t.Run("replace_all-regex-hit", func(t *testing.T) {
 		f([]ParsedRelabelConfig{
 			{
 				Action:                       "replace_all",
@@ -270,6 +292,7 @@ func TestApplyRelabelConfigs(t *testing.T) {
 				TargetLabel:                  "zar",
 				Regex:                        defaultRegexForRelabelConfig,
 				Replacement:                  "b-$1",
+				hasCaptureGroupInReplacement: true,
 			},
 		}, []prompbmarshal.Label{
 			{
@@ -444,6 +467,25 @@ func TestApplyRelabelConfigs(t *testing.T) {
 		}, true, []prompbmarshal.Label{})
 	})
 	t.Run("keep-hit", func(t *testing.T) {
+		f([]ParsedRelabelConfig{
+			{
+				Action:       "keep",
+				SourceLabels: []string{"foo"},
+				Regex:        regexp.MustCompile("yyy"),
+			},
+		}, []prompbmarshal.Label{
+			{
+				Name:  "foo",
+				Value: "yyy",
+			},
+		}, false, []prompbmarshal.Label{
+			{
+				Name:  "foo",
+				Value: "yyy",
+			},
+		})
+	})
+	t.Run("keep-hit-regexp", func(t *testing.T) {
 		f([]ParsedRelabelConfig{
 			{
 				Action:       "keep",
@@ -489,6 +531,20 @@ func TestApplyRelabelConfigs(t *testing.T) {
 		})
 	})
 	t.Run("drop-hit", func(t *testing.T) {
+		f([]ParsedRelabelConfig{
+			{
+				Action:       "drop",
+				SourceLabels: []string{"foo"},
+				Regex:        regexp.MustCompile("yyy"),
+			},
+		}, []prompbmarshal.Label{
+			{
+				Name:  "foo",
+				Value: "yyy",
+			},
+		}, true, []prompbmarshal.Label{})
+	})
+	t.Run("drop-hit-regexp", func(t *testing.T) {
 		f([]ParsedRelabelConfig{
 			{
 				Action:       "drop",
@@ -608,7 +664,80 @@ func TestApplyRelabelConfigs(t *testing.T) {
 			},
 		})
 	})
+	t.Run("labelmap_all-regexp", func(t *testing.T) {
+		f([]ParsedRelabelConfig{
+			{
+				Action:      "labelmap_all",
+				Regex:       regexp.MustCompile(`ba(.)`),
+				Replacement: "${1}ss",
+			},
+		}, []prompbmarshal.Label{
+			{
+				Name:  "foo.bar.baz",
+				Value: "yyy",
+			},
+			{
+				Name:  "foozar",
+				Value: "aaa",
+			},
+		}, true, []prompbmarshal.Label{
+			{
+				Name:  "foo.rss.zss",
+				Value: "yyy",
+			},
+			{
+				Name:  "foozar",
+				Value: "aaa",
+			},
+		})
+	})
 	t.Run("labeldrop", func(t *testing.T) {
+		f([]ParsedRelabelConfig{
+			{
+				Action: "labeldrop",
+				Regex:  regexp.MustCompile("dropme"),
+			},
+		}, []prompbmarshal.Label{
+			{
+				Name:  "aaa",
+				Value: "bbb",
+			},
+		}, true, []prompbmarshal.Label{
+			{
+				Name:  "aaa",
+				Value: "bbb",
+			},
+		})
+		f([]ParsedRelabelConfig{
+			{
+				Action: "labeldrop",
+				Regex:  regexp.MustCompile("dropme"),
+			},
+		}, []prompbmarshal.Label{
+			{
+				Name:  "xxx",
+				Value: "yyy",
+			},
+			{
+				Name:  "dropme",
+				Value: "aaa",
+			},
+			{
+				Name:  "foo",
+				Value: "bar",
+			},
+		}, false, []prompbmarshal.Label{
+			{
+				Name:  "foo",
+				Value: "bar",
+			},
+			{
+				Name:  "xxx",
+				Value: "yyy",
+			},
+		})
+	})
+	t.Run("labeldrop-regexp", func(t *testing.T) {
 		f([]ParsedRelabelConfig{
 			{
 				Action: "labeldrop",
@@ -655,6 +784,48 @@ func TestApplyRelabelConfigs(t *testing.T) {
 		})
 	})
 	t.Run("labelkeep", func(t *testing.T) {
+		f([]ParsedRelabelConfig{
+			{
+				Action: "labelkeep",
+				Regex:  regexp.MustCompile("keepme"),
+			},
+		}, []prompbmarshal.Label{
+			{
+				Name:  "keepme",
+				Value: "aaa",
+			},
+		}, true, []prompbmarshal.Label{
+			{
+				Name:  "keepme",
+				Value: "aaa",
+			},
+		})
+		f([]ParsedRelabelConfig{
+			{
+				Action: "labelkeep",
+				Regex:  regexp.MustCompile("keepme"),
+			},
+		}, []prompbmarshal.Label{
+			{
+				Name:  "keepme",
+				Value: "aaa",
+			},
+			{
+				Name:  "aaaa",
+				Value: "awef",
+			},
+			{
+				Name:  "keepme-aaa",
+				Value: "234",
+			},
+		}, false, []prompbmarshal.Label{
+			{
+				Name:  "keepme",
+				Value: "aaa",
+			},
+		})
+	})
+	t.Run("labelkeep-regexp", func(t *testing.T) {
 		f([]ParsedRelabelConfig{
 			{
 				Action: "labelkeep",

lib/promrelabel/relabel_timing_test.go

@@ -183,7 +183,7 @@ func BenchmarkApplyRelabelConfigs(b *testing.B) {
 			}
 		})
 	})
-	b.Run("replace-match", func(b *testing.B) {
+	b.Run("replace-match-regex", func(b *testing.B) {
 		prcs := []ParsedRelabelConfig{
 			{
 				Action:       "replace",
@@ -272,6 +272,37 @@ func BenchmarkApplyRelabelConfigs(b *testing.B) {
 		})
 	})
 	b.Run("drop-match", func(b *testing.B) {
+		prcs := []ParsedRelabelConfig{
+			{
+				Action:       "drop",
+				SourceLabels: []string{"id"},
+				Regex:        regexp.MustCompile("yes"),
+			},
+		}
+		labelsOrig := []prompbmarshal.Label{
+			{
+				Name:  "__name__",
+				Value: "metric",
+			},
+			{
+				Name:  "id",
+				Value: "yes",
+			},
+		}
+		b.ReportAllocs()
+		b.SetBytes(1)
+		b.RunParallel(func(pb *testing.PB) {
+			var labels []prompbmarshal.Label
+			for pb.Next() {
+				labels = append(labels[:0], labelsOrig...)
+				labels = ApplyRelabelConfigs(labels, 0, prcs, true)
+				if len(labels) != 0 {
+					panic(fmt.Errorf("unexpected number of labels; got %d; want %d; labels:\n%#v", len(labels), 0, labels))
+				}
+			}
+		})
+	})
+	b.Run("drop-match-regexp", func(b *testing.B) {
 		prcs := []ParsedRelabelConfig{
 			{
 				Action:       "drop",
@@ -334,6 +365,49 @@ func BenchmarkApplyRelabelConfigs(b *testing.B) {
 		})
 	})
 	b.Run("keep-match", func(b *testing.B) {
+		prcs := []ParsedRelabelConfig{
+			{
+				Action:       "keep",
+				SourceLabels: []string{"id"},
+				Regex:        regexp.MustCompile("yes"),
+			},
+		}
+		labelsOrig := []prompbmarshal.Label{
+			{
+				Name:  "__name__",
+				Value: "metric",
+			},
+			{
+				Name:  "id",
+				Value: "yes",
+			},
+		}
+		b.ReportAllocs()
+		b.SetBytes(1)
+		b.RunParallel(func(pb *testing.PB) {
+			var labels []prompbmarshal.Label
+			for pb.Next() {
+				labels = append(labels[:0], labelsOrig...)
+				labels = ApplyRelabelConfigs(labels, 0, prcs, true)
+				if len(labels) != len(labelsOrig) {
+					panic(fmt.Errorf("unexpected number of labels; got %d; want %d; labels:\n%#v", len(labels), len(labelsOrig), labels))
+				}
+				if labels[0].Name != "__name__" {
+					panic(fmt.Errorf("unexpected label name; got %q; want %q", labels[0].Name, "__name__"))
+				}
+				if labels[0].Value != "metric" {
+					panic(fmt.Errorf("unexpected label value; got %q; want %q", labels[0].Value, "metric"))
+				}
+				if labels[1].Name != "id" {
+					panic(fmt.Errorf("unexpected label name; got %q; want %q", labels[1].Name, "id"))
+				}
+				if labels[1].Value != "yes" {
+					panic(fmt.Errorf("unexpected label value; got %q; want %q", labels[1].Value, "yes"))
+				}
+			}
+		})
+	})
+	b.Run("keep-match-regexp", func(b *testing.B) {
 		prcs := []ParsedRelabelConfig{
 			{
 				Action:       "keep",
@@ -454,6 +528,42 @@ func BenchmarkApplyRelabelConfigs(b *testing.B) {
 			}
 		})
 	})
+	b.Run("labeldrop-match-regexp", func(b *testing.B) {
+		prcs := []ParsedRelabelConfig{
+			{
+				Action: "labeldrop",
+				Regex:  regexp.MustCompile("id.*"),
+			},
+		}
+		labelsOrig := []prompbmarshal.Label{
+			{
+				Name:  "__name__",
+				Value: "metric",
+			},
+			{
+				Name:  "id",
+				Value: "foobar-random-string-here",
+			},
+		}
+		b.ReportAllocs()
+		b.SetBytes(1)
+		b.RunParallel(func(pb *testing.PB) {
+			var labels []prompbmarshal.Label
+			for pb.Next() {
+				labels = append(labels[:0], labelsOrig...)
+				labels = ApplyRelabelConfigs(labels, 0, prcs, true)
+				if len(labels) != 1 {
+					panic(fmt.Errorf("unexpected number of labels; got %d; want %d; labels:\n%#v", len(labels), 1, labels))
+				}
+				if labels[0].Name != "__name__" {
+					panic(fmt.Errorf("unexpected label name; got %q; want %q", labels[0].Name, "__name__"))
+				}
+				if labels[0].Value != "metric" {
+					panic(fmt.Errorf("unexpected label value; got %q; want %q", labels[0].Value, "metric"))
+				}
+			}
+		})
+	})
 	b.Run("labelkeep-mismatch", func(b *testing.B) {
 		prcs := []ParsedRelabelConfig{
 			{
@@ -520,6 +630,91 @@ func BenchmarkApplyRelabelConfigs(b *testing.B) {
 			}
 		})
 	})
+	b.Run("labelkeep-match-regexp", func(b *testing.B) {
+		prcs := []ParsedRelabelConfig{
+			{
+				Action: "labelkeep",
+				Regex:  regexp.MustCompile("id.*"),
+			},
+		}
+		labelsOrig := []prompbmarshal.Label{
+			{
+				Name:  "__name__",
+				Value: "metric",
+			},
+			{
+				Name:  "id",
+				Value: "foobar-random-string-here",
+			},
+		}
+		b.ReportAllocs()
+		b.SetBytes(1)
+		b.RunParallel(func(pb *testing.PB) {
+			var labels []prompbmarshal.Label
+			for pb.Next() {
+				labels = append(labels[:0], labelsOrig...)
+				labels = ApplyRelabelConfigs(labels, 0, prcs, true)
+				if len(labels) != 1 {
+					panic(fmt.Errorf("unexpected number of labels; got %d; want %d; labels:\n%#v", len(labels), 1, labels))
+				}
+				if labels[0].Name != "id" {
+					panic(fmt.Errorf("unexpected label name; got %q; want %q", labels[0].Name, "id"))
+				}
+				if labels[0].Value != "foobar-random-string-here" {
+					panic(fmt.Errorf("unexpected label value; got %q; want %q", labels[0].Value, "foobar-random-string-here"))
+				}
+			}
+		})
+	})
+	b.Run("labelmap", func(b *testing.B) {
+		prcs := []ParsedRelabelConfig{
+			{
+				Action:      "labelmap",
+				Regex:       regexp.MustCompile("a(.*)"),
+				Replacement: "$1",
+			},
+		}
+		labelsOrig := []prompbmarshal.Label{
+			{
+				Name:  "aabc",
+				Value: "foobar-random-string-here",
+			},
+			{
+				Name:  "foo",
+				Value: "bar",
+			},
+		}
+		b.ReportAllocs()
+		b.SetBytes(1)
+		b.RunParallel(func(pb *testing.PB) {
+			var labels []prompbmarshal.Label
+			for pb.Next() {
+				labels = append(labels[:0], labelsOrig...)
+				labels = ApplyRelabelConfigs(labels, 0, prcs, true)
+				if len(labels) != 3 {
+					panic(fmt.Errorf("unexpected number of labels; got %d; want %d; labels:\n%#v", len(labels), 3, labels))
+				}
+				if labels[0].Name != "aabc" {
+					panic(fmt.Errorf("unexpected label name; got %q; want %q", labels[0].Name, "aabc"))
+				}
+				if labels[0].Value != "foobar-random-string-here" {
+					panic(fmt.Errorf("unexpected label value; got %q; want %q", labels[0].Value, "foobar-random-string-here"))
+				}
+				if labels[1].Name != "abc" {
+					panic(fmt.Errorf("unexpected label name; got %q; want %q", labels[1].Name, "abc"))
+				}
+				if labels[1].Value != "foobar-random-string-here" {
+					panic(fmt.Errorf("unexpected label value; got %q; want %q", labels[1].Value, "foobar-random-string-here"))
+				}
+				if labels[2].Name != "foo" {
+					panic(fmt.Errorf("unexpected label name; got %q; want %q", labels[2].Name, "foo"))
+				}
+				if labels[2].Value != "bar" {
+					panic(fmt.Errorf("unexpected label value; got %q; want %q", labels[2].Value, "bar"))
+				}
+			}
+		})
+	})
 	b.Run("hashmod", func(b *testing.B) {
 		prcs := []ParsedRelabelConfig{
 			{