lib/regexutil: cache MatchString results for unoptimized regexps

This increases relabeling performance by 3x for unoptimized regexs

lib/bytesutil/fast_string_matcher.go

@@ -0,0 +1,48 @@
+package bytesutil
+
+import (
+	"sync"
+	"sync/atomic"
+)
+
+// FastStringMatcher implements fast matcher for strings.
+//
+// It caches string match results and returns them back on the next calls
+// without calling the matchFunc, which may be expensive.
+type FastStringMatcher struct {
+	m    atomic.Value
+	mLen uint64
+
+	matchFunc func(s string) bool
+}
+
+// NewFastStringMatcher creates new matcher, which applies matchFunc to strings passed to Match()
+//
+// matchFunc must return the same result for the same input.
+func NewFastStringMatcher(matchFunc func(s string) bool) *FastStringMatcher {
+	var fsm FastStringMatcher
+	fsm.m.Store(&sync.Map{})
+	fsm.matchFunc = matchFunc
+	return &fsm
+}
+
+// Match applies matchFunc to s and returns the result.
+func (fsm *FastStringMatcher) Match(s string) bool {
+	m := fsm.m.Load().(*sync.Map)
+	v, ok := m.Load(s)
+	if ok {
+		// Fast path - s match result is found in the cache.
+		bp := v.(*bool)
+		return *bp
+	}
+	// Slow path - run matchFunc for s and store the result in the cache.
+	b := fsm.matchFunc(s)
+	bp := &b
+	m.Store(s, bp)
+	n := atomic.AddUint64(&fsm.mLen, 1)
+	if n > 100e3 {
+		atomic.StoreUint64(&fsm.mLen, 0)
+		fsm.m.Store(&sync.Map{})
+	}
+	return b
+}

lib/bytesutil/fast_string_matcher_test.go

@@ -0,0 +1,25 @@
+package bytesutil
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestFastStringMatcher(t *testing.T) {
+	fsm := NewFastStringMatcher(func(s string) bool {
+		return strings.HasPrefix(s, "foo")
+	})
+	f := func(s string, resultExpected bool) {
+		t.Helper()
+		for i := 0; i < 10; i++ {
+			result := fsm.Match(s)
+			if result != resultExpected {
+				t.Fatalf("unexpected result for Match(%q) at iteration %d; got %v; want %v", s, i, result, resultExpected)
+			}
+		}
+	}
+	f("", false)
+	f("foo", true)
+	f("a_b-C", false)
+	f("foobar", true)
+}

lib/bytesutil/fast_string_matcher_timing_test.go

@@ -0,0 +1,33 @@
+package bytesutil
+
+import (
+	"strings"
+	"sync/atomic"
+	"testing"
+)
+
+func BenchmarkFastStringMatcher(b *testing.B) {
+	for _, s := range []string{"", "foo", "foo-bar-baz", "http_requests_total"} {
+		b.Run(s, func(b *testing.B) {
+			benchmarkFastStringMatcher(b, s)
+		})
+	}
+}
+
+func benchmarkFastStringMatcher(b *testing.B, s string) {
+	fsm := NewFastStringMatcher(func(s string) bool {
+		return strings.HasPrefix(s, "foo")
+	})
+	b.ReportAllocs()
+	b.SetBytes(1)
+	b.RunParallel(func(pb *testing.PB) {
+		n := uint64(0)
+		for pb.Next() {
+			v := fsm.Match(s)
+			if v {
+				n++
+			}
+		}
+		atomic.AddUint64(&GlobalSink, n)
+	})
+}

lib/bytesutil/fast_string_transformer_timing_test.go

@@ -2,6 +2,7 @@ package bytesutil
 
 import (
 	"strings"
+	"sync/atomic"
 	"testing"
 )
 
@@ -18,11 +19,13 @@ func benchmarkFastStringTransformer(b *testing.B, s string) {
 	b.ReportAllocs()
 	b.SetBytes(1)
 	b.RunParallel(func(pb *testing.PB) {
+		n := uint64(0)
 		for pb.Next() {
 			sTransformed := fst.Transform(s)
-			GlobalSink += len(sTransformed)
+			n += uint64(len(sTransformed))
 		}
+		atomic.AddUint64(&GlobalSink, n)
 	})
 }
 
-var GlobalSink int
+var GlobalSink uint64

lib/promscrape/config_test.go

@@ -674,8 +674,9 @@ scrape_config_files:
 }
 
 func resetNonEssentialFields(sws []*ScrapeWork) {
-	for i := range sws {
-		sws[i].OriginalLabels = nil
+	for _, sw := range sws {
+		sw.OriginalLabels = nil
+		sw.MetricRelabelConfigs = nil
 	}
 }
 
@@ -1446,10 +1447,6 @@ scrape_configs:
 			},
 			AuthConfig:      &promauth.Config{},
 			ProxyAuthConfig: &promauth.Config{},
-			MetricRelabelConfigs: mustParseRelabelConfigs(`
-- source_labels: [foo]
-  target_label: abc
-`),
 			jobNameOriginal: "foo",
 		},
 	})
@@ -1847,8 +1844,10 @@ func TestScrapeConfigClone(t *testing.T) {
 	f := func(sc *ScrapeConfig) {
 		t.Helper()
 		scCopy := sc.clone()
-		if !reflect.DeepEqual(sc, scCopy) {
-			t.Fatalf("unexpected result after unmarshalJSON() for JSON:\n%s", sc.marshalJSON())
+		scJSON := sc.marshalJSON()
+		scCopyJSON := scCopy.marshalJSON()
+		if !reflect.DeepEqual(scJSON, scCopyJSON) {
+			t.Fatalf("unexpected cloned result:\ngot\n%s\nwant\n%s", scCopyJSON, scJSON)
 		}
 	}
 

lib/regexutil/promregex.go

@@ -3,6 +3,8 @@ package regexutil
 import (
 	"regexp"
 	"strings"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
 )
 
 // PromRegex implements an optimized string matching for Prometheus-like regex.
@@ -13,6 +15,8 @@ import (
 // - alternate strings such as "foo|bar|baz"
 // - prefix match such as "foo.*" or "foo.+"
 // - substring match such as ".*foo.*" or ".+bar.+"
+//
+// The rest of regexps are also optimized by returning cached match results for the same input strings.
 type PromRegex struct {
 	// prefix contains literal prefix for regex.
 	// For example, prefix="foo" for regex="foo(a|b)"
@@ -32,9 +36,8 @@ type PromRegex struct {
 	// For example, orValues contain ["foo","bar","baz"] for regex suffix="foo|bar|baz"
 	orValues []string
 
-	// reSuffix contains an anchored regexp built from suffix:
-	// "^(?:suffix)$"
-	reSuffix *regexp.Regexp
+	// reSuffixMatcher contains fast matcher for "^suffix$"
+	reSuffixMatcher *bytesutil.FastStringMatcher
 }
 
 // NewPromRegex returns PromRegex for the given expr.
@@ -50,13 +53,14 @@ func NewPromRegex(expr string) (*PromRegex, error) {
 	// Anchor suffix to the beginning and the end of the matching string.
 	suffixExpr := "^(?:" + suffix + ")$"
 	reSuffix := regexp.MustCompile(suffixExpr)
+	reSuffixMatcher := bytesutil.NewFastStringMatcher(reSuffix.MatchString)
 	pr := &PromRegex{
 		prefix:          prefix,
 		suffix:          suffix,
 		substrDotStar:   substrDotStar,
 		substrDotPlus:   substrDotPlus,
 		orValues:        orValues,
-		reSuffix:      reSuffix,
+		reSuffixMatcher: reSuffixMatcher,
 	}
 	return pr, nil
 }
@@ -106,7 +110,7 @@ func (pr *PromRegex) MatchString(s string) bool {
 		return len(s) > 0
 	}
 	// Fall back to slow path by matching the original regexp.
-	return pr.reSuffix.MatchString(s)
+	return pr.reSuffixMatcher.Match(s)
 }
 
 func getSubstringLiteral(expr, prefixSuffix string) string {