lib/regexutil: add Simplify() function for simplifying the regular expression

lib/promrelabel/config.go

@@ -197,14 +197,19 @@ func parseRelabelConfig(rc *RelabelConfig) (*parsedRelabelConfig, error) {
 	if rc.Separator != nil {
 		separator = *rc.Separator
 	}
+	action := strings.ToLower(rc.Action)
+	if action == "" {
+		action = "replace"
+	}
 	targetLabel := rc.TargetLabel
 	regexCompiled := defaultRegexForRelabelConfig
 	regexOriginalCompiled := defaultOriginalRegexForRelabelConfig
 	var regexOrValues []string
-	if rc.Regex != nil {
-		regex := regexutil.RemoveStartEndAnchors(rc.Regex.S)
+	if rc.Regex != nil && !isDefaultRegex(rc.Regex.S) {
+		regex := rc.Regex.S
 		regexOrig := regex
 		if rc.Action != "replace_all" && rc.Action != "labelmap_all" {
+			regex = regexutil.RemoveStartEndAnchors(regex)
 			regex = "^(?:" + regex + ")$"
 		}
 		re, err := regexp.Compile(regex)
@@ -232,10 +237,6 @@ func parseRelabelConfig(rc *RelabelConfig) (*parsedRelabelConfig, error) {
 	if rc.Labels != nil {
 		graphiteLabelRules = newGraphiteLabelRules(rc.Labels)
 	}
-	action := rc.Action
-	if action == "" {
-		action = "replace"
-	}
 	switch action {
 	case "graphite":
 		if graphiteMatchTemplate == nil {
@@ -354,3 +355,11 @@ func parseRelabelConfig(rc *RelabelConfig) (*parsedRelabelConfig, error) {
 		hasLabelReferenceInReplacement: strings.Contains(replacement, "{{"),
 	}, nil
 }
+
+func isDefaultRegex(expr string) bool {
+	prefix, suffix := regexutil.Simplify(expr)
+	if prefix != "" {
+		return false
+	}
+	return suffix == ".*"
+}

lib/promrelabel/config_test.go

@@ -455,3 +455,21 @@ func TestParseRelabelConfigsFailure(t *testing.T) {
 		})
 	})
 }
+
+func TestIsDefaultRegex(t *testing.T) {
+	f := func(s string, resultExpected bool) {
+		t.Helper()
+		result := isDefaultRegex(s)
+		if result != resultExpected {
+			t.Fatalf("unexpected result for isDefaultRegex(%q); got %v; want %v", s, result, resultExpected)
+		}
+	}
+	f("", false)
+	f("foo", false)
+	f(".+", false)
+	f("a.*", false)
+	f(".*", true)
+	f("(.*)", true)
+	f("^.*$", true)
+	f("(?:.*)", true)
+}

lib/regexutil/regexutil.go

@@ -1,11 +1,10 @@
 package regexutil
 
 import (
+	"fmt"
 	"regexp/syntax"
 	"sort"
 	"strings"
-
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 )
 
 // RemoveStartEndAnchors removes '^' at the start of expr and '$' at the end of the expr.
@@ -28,15 +27,26 @@ func RemoveStartEndAnchors(expr string) string {
 // It returns an empty list if it is impossible to extract "or" values from the regexp.
 func GetOrValues(expr string) []string {
 	expr = RemoveStartEndAnchors(expr)
-	sre, err := syntax.Parse(expr, syntax.Perl)
+	prefix, tailExpr := Simplify(expr)
+	if tailExpr == "" {
+		return []string{prefix}
+	}
+	sre, err := syntax.Parse(tailExpr, syntax.Perl)
 	if err != nil {
-		logger.Panicf("BUG: unexpected error when parsing verified expr=%q: %s", expr, err)
+		panic(fmt.Errorf("BUG: unexpected error when parsing verified tailExpr=%q: %w", tailExpr, err))
 	}
 	orValues := getOrValuesExt(sre)
 
 	// Sort orValues for faster index seek later
 	sort.Strings(orValues)
 
+	if len(prefix) > 0 {
+		// Add prefix to orValues
+		for i, orValue := range orValues {
+			orValues[i] = prefix + orValue
+		}
+	}
+
 	return orValues
 }
 
@@ -51,8 +61,6 @@ func getOrValuesExt(sre *syntax.Regexp) []string {
 		return []string{string(sre.Rune)}
 	case syntax.OpEmptyMatch:
 		return []string{""}
-	case syntax.OpBeginText, syntax.OpEndText:
-		return []string{""}
 	case syntax.OpAlternate:
 		a := make([]string, 0, len(sre.Sub))
 		for _, reSub := range sre.Sub {
@@ -90,6 +98,9 @@ func getOrValuesExt(sre *syntax.Regexp) []string {
 		if len(prefixes) == 0 {
 			return nil
 		}
+		if len(sre.Sub) == 1 {
+			return prefixes
+		}
 		sre.Sub = sre.Sub[1:]
 		suffixes := getOrValuesExt(sre)
 		if len(suffixes) == 0 {
@@ -120,3 +131,129 @@ func isLiteral(sre *syntax.Regexp) bool {
 }
 
 const maxOrValues = 100
+
+// Simplify simplifies the given expr.
+//
+// It returns plaintext prefix and the remaining regular expression
+// with dropped '^' and '$' anchors at the beginning and the end
+// of the regular expression.
+//
+// The function removes capturing parens from the expr,
+// so it cannot be used when capturing parens are necessary.
+func Simplify(expr string) (string, string) {
+	sre, err := syntax.Parse(expr, syntax.Perl)
+	if err != nil {
+		// Cannot parse the regexp. Return it all as prefix.
+		return expr, ""
+	}
+	sre = simplifyRegexp(sre, false)
+	if sre == emptyRegexp {
+		return "", ""
+	}
+	if isLiteral(sre) {
+		return string(sre.Rune), ""
+	}
+	var prefix string
+	if sre.Op == syntax.OpConcat {
+		sub0 := sre.Sub[0]
+		if isLiteral(sub0) {
+			prefix = string(sub0.Rune)
+			sre.Sub = sre.Sub[1:]
+			if len(sre.Sub) == 0 {
+				return prefix, ""
+			}
+			sre = simplifyRegexp(sre, true)
+		}
+	}
+	if _, err := syntax.Compile(sre); err != nil {
+		// Cannot compile the regexp. Return it all as prefix.
+		return expr, ""
+	}
+	s := sre.String()
+	s = strings.ReplaceAll(s, "(?:)", "")
+	s = strings.ReplaceAll(s, "(?-s:.)", ".")
+	s = strings.ReplaceAll(s, "(?-m:$)", "$")
+	return prefix, s
+}
+
+func simplifyRegexp(sre *syntax.Regexp, hasPrefix bool) *syntax.Regexp {
+	s := sre.String()
+	for {
+		sre = simplifyRegexpExt(sre, hasPrefix, false)
+		sre = sre.Simplify()
+		if sre.Op == syntax.OpBeginText || sre.Op == syntax.OpEndText {
+			sre = emptyRegexp
+		}
+		sNew := sre.String()
+		if sNew == s {
+			return sre
+		}
+		var err error
+		sre, err = syntax.Parse(sNew, syntax.Perl)
+		if err != nil {
+			panic(fmt.Errorf("BUG: cannot parse simplified regexp %q: %w", sNew, err))
+		}
+		s = sNew
+	}
+}
+
+func simplifyRegexpExt(sre *syntax.Regexp, hasPrefix, hasSuffix bool) *syntax.Regexp {
+	switch sre.Op {
+	case syntax.OpCapture:
+		// Substitute all the capture regexps with non-capture regexps.
+		sre.Op = syntax.OpAlternate
+		sre.Sub[0] = simplifyRegexpExt(sre.Sub[0], hasPrefix, hasSuffix)
+		if sre.Sub[0] == emptyRegexp {
+			return emptyRegexp
+		}
+		return sre
+	case syntax.OpStar, syntax.OpPlus, syntax.OpQuest, syntax.OpRepeat:
+		sre.Sub[0] = simplifyRegexpExt(sre.Sub[0], hasPrefix, hasSuffix)
+		if sre.Sub[0] == emptyRegexp {
+			return emptyRegexp
+		}
+		return sre
+	case syntax.OpAlternate:
+		// Do not remove empty captures from OpAlternate, since this may break regexp.
+		for i, sub := range sre.Sub {
+			sre.Sub[i] = simplifyRegexpExt(sub, hasPrefix, hasSuffix)
+		}
+		return sre
+	case syntax.OpConcat:
+		subs := sre.Sub[:0]
+		for i, sub := range sre.Sub {
+			sub = simplifyRegexpExt(sub, hasPrefix || len(subs) > 0, hasSuffix || i+1 < len(sre.Sub))
+			if sub != emptyRegexp {
+				subs = append(subs, sub)
+			}
+		}
+		sre.Sub = subs
+		// Remove anchros from the beginning and the end of regexp, since they
+		// will be added later.
+		if !hasPrefix {
+			for len(sre.Sub) > 0 && sre.Sub[0].Op == syntax.OpBeginText {
+				sre.Sub = sre.Sub[1:]
+			}
+		}
+		if !hasSuffix {
+			for len(sre.Sub) > 0 && sre.Sub[len(sre.Sub)-1].Op == syntax.OpEndText {
+				sre.Sub = sre.Sub[:len(sre.Sub)-1]
+			}
+		}
+		if len(sre.Sub) == 0 {
+			return emptyRegexp
+		}
+		if len(sre.Sub) == 1 {
+			return sre.Sub[0]
+		}
+		return sre
+	case syntax.OpEmptyMatch:
+		return emptyRegexp
+	default:
+		return sre
+	}
+}
+
+var emptyRegexp = &syntax.Regexp{
+	Op: syntax.OpEmptyMatch,
+}

lib/regexutil/regexutil_test.go

@@ -23,6 +23,7 @@ func TestGetOrValues(t *testing.T) {
 	f("foo.*", nil)
 	f(".*", nil)
 	f("foo|.*", nil)
+	f("(fo((o)))|(bar)", []string{"bar", "foo"})
 	f("foobar", []string{"foobar"})
 	f("z|x|c", []string{"c", "x", "z"})
 	f("foo|bar", []string{"bar", "foo"})
@@ -41,8 +42,71 @@ func TestGetOrValues(t *testing.T) {
 	f("^foo|bar$", []string{"bar", "foo"})
 	f("^(foo|bar)$", []string{"bar", "foo"})
 	f("^a(foo|b(?:a|r))$", []string{"aba", "abr", "afoo"})
-	// This is incorrect conversion, because the regexp matches nothing.
-	// It is OK for now, since such regexps are uncommon in practice.
-	// TODO: properly handle this case.
-	f("^a(^foo|bar$)z$", []string{"abarz", "afooz"})
+	f("^a(foo$|b(?:a$|r))$", []string{"aba", "abr", "afoo"})
+	f("^a(^foo|bar$)z$", nil)
+}
+
+func TestSimplify(t *testing.T) {
+	f := func(s, expectedPrefix, expectedSuffix string) {
+		t.Helper()
+		prefix, suffix := Simplify(s)
+		if prefix != expectedPrefix {
+			t.Fatalf("unexpected prefix for s=%q; got %q; want %q", s, prefix, expectedPrefix)
+		}
+		if suffix != expectedSuffix {
+			t.Fatalf("unexpected suffix for s=%q; got %q; want %q", s, suffix, expectedSuffix)
+		}
+	}
+
+	f("", "", "")
+	f("^", "", "")
+	f("$", "", "")
+	f("^()$", "", "")
+	f("^(?:)$", "", "")
+	f("^foo|^bar$|baz", "", "foo|ba[rz]")
+	f("^(foo$|^bar)$", "", "foo|bar")
+	f("^a(foo$|bar)$", "a", "foo|bar")
+	f("^a(^foo|bar$)z$", "a", "(?:\\Afoo|bar$)z")
+	f("foobar", "foobar", "")
+	f("foo$|^foobar", "foo", "|bar")
+	f("^(foo$|^foobar)$", "foo", "|bar")
+	f("foobar|foobaz", "fooba", "[rz]")
+	f("(fo|(zar|bazz)|x)", "", "fo|zar|bazz|x")
+	f("(тестЧЧ|тест)", "тест", "ЧЧ|")
+	f("foo(bar|baz|bana)", "fooba", "[rz]|na")
+	f("^foobar|foobaz", "fooba", "[rz]")
+	f("^foobar|^foobaz$", "fooba", "[rz]")
+	f("foobar|foobaz", "fooba", "[rz]")
+	f("(?:^foobar|^foobaz)aa.*", "fooba", "[rz]aa.*")
+	f("foo[bar]+", "foo", "[a-br]+")
+	f("foo[a-z]+", "foo", "[a-z]+")
+	f("foo[bar]*", "foo", "[a-br]*")
+	f("foo[a-z]*", "foo", "[a-z]*")
+	f("foo[x]+", "foo", "x+")
+	f("foo[^x]+", "foo", "[^x]+")
+	f("foo[x]*", "foo", "x*")
+	f("foo[^x]*", "foo", "[^x]*")
+	f("foo[x]*bar", "foo", "x*bar")
+	f("fo\\Bo[x]*bar?", "fo", "\\Box*bar?")
+	f("foo.+bar", "foo", ".+bar")
+	f("a(b|c.*).+", "a", "(?:b|c.*).+")
+	f("ab|ac", "a", "[b-c]")
+	f("(?i)xyz", "", "(?i:XYZ)")
+	f("(?i)foo|bar", "", "(?i:FOO)|(?i:BAR)")
+	f("(?i)up.+x", "", "(?i:UP).+(?i:X)")
+	f("(?smi)xy.*z$", "", "(?i:XY)(?s:.)*(?i:Z)(?m:$)")
+
+	// test invalid regexps
+	f("a(", "a(", "")
+	f("a[", "a[", "")
+	f("a[]", "a[]", "")
+	f("a{", "a{", "")
+	f("a{}", "a{}", "")
+	f("invalid(regexp", "invalid(regexp", "")
+
+	// The transformed regexp mustn't match aba
+	f("a?(^ba|c)", "", "a?(?:\\Aba|c)")
+
+	// The transformed regexp mustn't match barx
+	f("(foo|bar$)x*", "", "(?:foo|bar$)x*")
 }

lib/storage/metric_name.go

@@ -66,8 +66,8 @@ func (tag *Tag) copyFrom(src *Tag) {
 	tag.Value = append(tag.Value[:0], src.Value...)
 }
 
-func marshalTagValueNoTrailingTagSeparator(dst, src []byte) []byte {
-	dst = marshalTagValue(dst, src)
+func marshalTagValueNoTrailingTagSeparator(dst []byte, src string) []byte {
+	dst = marshalTagValue(dst, bytesutil.ToUnsafeBytes(src))
 	// Remove trailing tagSeparatorChar
 	return dst[:len(dst)-1]
 }

lib/storage/tag_filters.go

@@ -363,7 +363,7 @@ func (tf *tagFilter) InitFromGraphiteQuery(commonPrefix, query []byte, paths []s
 	tf.regexpPrefix = prefix
 	tf.prefix = append(tf.prefix[:0], commonPrefix...)
 	tf.prefix = marshalTagValue(tf.prefix, nil)
-	tf.prefix = marshalTagValueNoTrailingTagSeparator(tf.prefix, []byte(prefix))
+	tf.prefix = marshalTagValueNoTrailingTagSeparator(tf.prefix, prefix)
 	tf.orSuffixes = append(tf.orSuffixes[:0], orSuffixes...)
 	tf.reSuffixMatch, tf.matchCost = newMatchFuncForOrSuffixes(orSuffixes)
 }
@@ -419,15 +419,15 @@ func (tf *tagFilter) Init(commonPrefix, key, value []byte, isNegative, isRegexp
 	tf.prefix = append(tf.prefix, commonPrefix...)
 	tf.prefix = marshalTagValue(tf.prefix, key)
 
-	var expr []byte
-	prefix := tf.value
+	var expr string
+	prefix := bytesutil.ToUnsafeString(tf.value)
 	if tf.isRegexp {
-		prefix, expr = getRegexpPrefix(tf.value)
+		prefix, expr = simplifyRegexp(prefix)
 		if len(expr) == 0 {
 			tf.value = append(tf.value[:0], prefix...)
 			tf.isRegexp = false
 		} else {
-			tf.regexpPrefix = string(prefix)
+			tf.regexpPrefix = prefix
 		}
 	}
 	tf.prefix = marshalTagValueNoTrailingTagSeparator(tf.prefix, prefix)
@@ -508,22 +508,22 @@ func RegexpCacheMisses() uint64 {
 	return regexpCache.Misses()
 }
 
-func getRegexpFromCache(expr []byte) (*regexpCacheValue, error) {
-	if rcv := regexpCache.GetEntry(bytesutil.ToUnsafeString(expr)); rcv != nil {
+func getRegexpFromCache(expr string) (*regexpCacheValue, error) {
+	if rcv := regexpCache.GetEntry(expr); rcv != nil {
 		// Fast path - the regexp found in the cache.
 		return rcv.(*regexpCacheValue), nil
 	}
 	// Slow path - build the regexp.
-	exprOrig := string(expr)
+	exprOrig := expr
 
-	expr = []byte(tagCharsRegexpEscaper.Replace(exprOrig))
+	expr = tagCharsRegexpEscaper.Replace(exprOrig)
 	exprStr := fmt.Sprintf("^(%s)$", expr)
 	re, err := regexp.Compile(exprStr)
 	if err != nil {
 		return nil, fmt.Errorf("invalid regexp %q: %w", exprStr, err)
 	}
 
-	sExpr := string(expr)
+	sExpr := expr
 	orValues := regexutil.GetOrValues(sExpr)
 	var reMatch func(b []byte) bool
 	var reCost uint64
@@ -835,22 +835,28 @@ func (rcv *regexpCacheValue) SizeBytes() int {
 	return rcv.sizeBytes
 }
 
-func getRegexpPrefix(b []byte) ([]byte, []byte) {
-	// Fast path - search the prefix in the cache.
-	if ps := prefixesCache.GetEntry(bytesutil.ToUnsafeString(b)); ps != nil {
+func simplifyRegexp(expr string) (string, string) {
+	// It is safe to pass the expr constructed via bytesutil.ToUnsafeString()
+	// to GetEntry() here.
+	if ps := prefixesCache.GetEntry(expr); ps != nil {
+		// Fast path - the simplified expr is found in the cache.
 		ps := ps.(*prefixSuffix)
 		return ps.prefix, ps.suffix
 	}
 
-	// Slow path - extract the regexp prefix from b.
-	prefix, suffix := extractRegexpPrefix(b)
+	// Slow path - simplify the expr.
+
+	// Make a copy of expr before using it,
+	// since it may be constructed via bytesutil.ToUnsafeString()
+	expr = string(append([]byte{}, expr...))
+	prefix, suffix := regexutil.Simplify(expr)
 
 	// Put the prefix and the suffix to the cache.
 	ps := &prefixSuffix{
 		prefix: prefix,
 		suffix: suffix,
 	}
-	prefixesCache.PutEntry(string(b), ps)
+	prefixesCache.PutEntry(expr, ps)
 
 	return prefix, suffix
 }
@@ -897,120 +903,11 @@ func RegexpPrefixesCacheMisses() uint64 {
 }
 
 type prefixSuffix struct {
-	prefix []byte
-	suffix []byte
+	prefix string
+	suffix string
 }
 
 // SizeBytes implements lrucache.Entry interface
 func (ps *prefixSuffix) SizeBytes() int {
-	return cap(ps.prefix) + cap(ps.suffix) + int(unsafe.Sizeof(*ps))
-}
-
-func extractRegexpPrefix(b []byte) ([]byte, []byte) {
-	sre, err := syntax.Parse(string(b), syntax.Perl)
-	if err != nil {
-		// Cannot parse the regexp. Return it all as prefix.
-		return b, nil
-	}
-	sre = simplifyRegexp(sre)
-	if sre == emptyRegexp {
-		return nil, nil
-	}
-	if isLiteral(sre) {
-		return []byte(string(sre.Rune)), nil
-	}
-	var prefix []byte
-	if sre.Op == syntax.OpConcat {
-		sub0 := sre.Sub[0]
-		if isLiteral(sub0) {
-			prefix = []byte(string(sub0.Rune))
-			sre.Sub = sre.Sub[1:]
-			if len(sre.Sub) == 0 {
-				return nil, nil
-			}
-		}
-	}
-	if _, err := syntax.Compile(sre); err != nil {
-		// Cannot compile the regexp. Return it all as prefix.
-		return b, nil
-	}
-	return prefix, []byte(sre.String())
-}
-
-func simplifyRegexp(sre *syntax.Regexp) *syntax.Regexp {
-	s := sre.String()
-	for {
-		sre = simplifyRegexpExt(sre, false, false)
-		sre = sre.Simplify()
-		if sre.Op == syntax.OpBeginText || sre.Op == syntax.OpEndText {
-			sre = emptyRegexp
-		}
-		sNew := sre.String()
-		if sNew == s {
-			return sre
-		}
-		var err error
-		sre, err = syntax.Parse(sNew, syntax.Perl)
-		if err != nil {
-			logger.Panicf("BUG: cannot parse simplified regexp %q: %s", sNew, err)
-		}
-		s = sNew
-	}
-}
-
-func simplifyRegexpExt(sre *syntax.Regexp, hasPrefix, hasSuffix bool) *syntax.Regexp {
-	switch sre.Op {
-	case syntax.OpCapture:
-		// Substitute all the capture regexps with non-capture regexps.
-		sre.Op = syntax.OpAlternate
-		sre.Sub[0] = simplifyRegexpExt(sre.Sub[0], hasPrefix, hasSuffix)
-		if sre.Sub[0] == emptyRegexp {
-			return emptyRegexp
-		}
-		return sre
-	case syntax.OpStar, syntax.OpPlus, syntax.OpQuest, syntax.OpRepeat:
-		sre.Sub[0] = simplifyRegexpExt(sre.Sub[0], hasPrefix, hasSuffix)
-		if sre.Sub[0] == emptyRegexp {
-			return emptyRegexp
-		}
-		return sre
-	case syntax.OpAlternate:
-		// Do not remove empty captures from OpAlternate, since this may break regexp.
-		for i, sub := range sre.Sub {
-			sre.Sub[i] = simplifyRegexpExt(sub, hasPrefix, hasSuffix)
-		}
-		return sre
-	case syntax.OpConcat:
-		subs := sre.Sub[:0]
-		for i, sub := range sre.Sub {
-			if sub = simplifyRegexpExt(sub, i > 0, i+1 < len(sre.Sub)); sub != emptyRegexp {
-				subs = append(subs, sub)
-			}
-		}
-		sre.Sub = subs
-		// Remove anchros from the beginning and the end of regexp, since they
-		// will be added later.
-		if !hasPrefix {
-			for len(sre.Sub) > 0 && sre.Sub[0].Op == syntax.OpBeginText {
-				sre.Sub = sre.Sub[1:]
-			}
-		}
-		if !hasSuffix {
-			for len(sre.Sub) > 0 && sre.Sub[len(sre.Sub)-1].Op == syntax.OpEndText {
-				sre.Sub = sre.Sub[:len(sre.Sub)-1]
-			}
-		}
-		if len(sre.Sub) == 0 {
-			return emptyRegexp
-		}
-		return sre
-	case syntax.OpEmptyMatch:
-		return emptyRegexp
-	default:
-		return sre
-	}
-}
-
-var emptyRegexp = &syntax.Regexp{
-	Op: syntax.OpEmptyMatch,
+	return len(ps.prefix) + len(ps.suffix) + int(unsafe.Sizeof(*ps))
 }

lib/storage/tag_filters_test.go

@@ -675,26 +675,11 @@ func TestGetCommonPrefix(t *testing.T) {
 	f([]string{"foo1", "foo2", "foo34"}, "foo")
 }
 
-func TestExtractRegexpPrefix(t *testing.T) {
-	f := func(s string, expectedPrefix, expectedSuffix string) {
-		t.Helper()
-		prefix, suffix := extractRegexpPrefix([]byte(s))
-		if string(prefix) != expectedPrefix {
-			t.Fatalf("unexpected prefix for %q; got %q; want %q", s, prefix, expectedPrefix)
-		}
-		if string(suffix) != expectedSuffix {
-			t.Fatalf("unexpected suffix for %q; got %q; want %q", s, suffix, expectedSuffix)
-		}
-	}
-	f("", "", "")
-	f("foobar", "foobar", "")
-}
-
 func TestGetRegexpFromCache(t *testing.T) {
 	f := func(s string, orValuesExpected, expectedMatches, expectedMismatches []string, suffixExpected string) {
 		t.Helper()
 		for i := 0; i < 3; i++ {
-			rcv, err := getRegexpFromCache([]byte(s))
+			rcv, err := getRegexpFromCache(s)
 			if err != nil {
 				t.Fatalf("unexpected error for s=%q: %s", s, err)
 			}
@@ -764,7 +749,7 @@ func TestTagFilterMatchSuffix(t *testing.T) {
 	var tf tagFilter
 
 	tvNoTrailingTagSeparator := func(s string) string {
-		return string(marshalTagValueNoTrailingTagSeparator(nil, []byte(s)))
+		return string(marshalTagValueNoTrailingTagSeparator(nil, s))
 	}
 	init := func(value string, isNegative, isRegexp bool, expectedPrefix string) {
 		t.Helper()
@@ -1145,75 +1130,75 @@ func TestTagFilterMatchSuffix(t *testing.T) {
 	})
 }
 
-func TestGetRegexpPrefix(t *testing.T) {
-	f := func(t *testing.T, s, expectedPrefix, expectedSuffix string) {
+func TestSimplifyRegexp(t *testing.T) {
+	f := func(s, expectedPrefix, expectedSuffix string) {
 		t.Helper()
 
-		prefix, suffix := getRegexpPrefix([]byte(s))
-		if string(prefix) != expectedPrefix {
+		prefix, suffix := simplifyRegexp(s)
+		if prefix != expectedPrefix {
 			t.Fatalf("unexpected prefix for s=%q; got %q; want %q", s, prefix, expectedPrefix)
 		}
-		if string(suffix) != expectedSuffix {
+		if suffix != expectedSuffix {
 			t.Fatalf("unexpected suffix for s=%q; got %q; want %q", s, suffix, expectedSuffix)
 		}
 
 		// Get the prefix from cache.
-		prefix, suffix = getRegexpPrefix([]byte(s))
-		if string(prefix) != expectedPrefix {
+		prefix, suffix = simplifyRegexp(s)
+		if prefix != expectedPrefix {
 			t.Fatalf("unexpected prefix for s=%q; got %q; want %q", s, prefix, expectedPrefix)
 		}
-		if string(suffix) != expectedSuffix {
+		if suffix != expectedSuffix {
 			t.Fatalf("unexpected suffix for s=%q; got %q; want %q", s, suffix, expectedSuffix)
 		}
 	}
 
-	f(t, "", "", "")
-	f(t, "^", "", "")
-	f(t, "$", "", "")
-	f(t, "^()$", "", "")
-	f(t, "^(?:)$", "", "")
-	f(t, "foobar", "foobar", "")
-	f(t, "foo$|^foobar", "foo", "(?:(?:)|bar)")
-	f(t, "^(foo$|^foobar)$", "foo", "(?:(?:)|bar)")
-	f(t, "foobar|foobaz", "fooba", "[rz]")
-	f(t, "(fo|(zar|bazz)|x)", "", "fo|zar|bazz|x")
-	f(t, "(тестЧЧ|тест)", "тест", "(?:ЧЧ|(?:))")
-	f(t, "foo(bar|baz|bana)", "fooba", "(?:[rz]|na)")
-	f(t, "^foobar|foobaz", "fooba", "[rz]")
-	f(t, "^foobar|^foobaz$", "fooba", "[rz]")
-	f(t, "foobar|foobaz", "fooba", "[rz]")
-	f(t, "(?:^foobar|^foobaz)aa.*", "fooba", "[rz]aa(?-s:.)*")
-	f(t, "foo[bar]+", "foo", "[a-br]+")
-	f(t, "foo[a-z]+", "foo", "[a-z]+")
-	f(t, "foo[bar]*", "foo", "[a-br]*")
-	f(t, "foo[a-z]*", "foo", "[a-z]*")
-	f(t, "foo[x]+", "foo", "x+")
-	f(t, "foo[^x]+", "foo", "[^x]+")
-	f(t, "foo[x]*", "foo", "x*")
-	f(t, "foo[^x]*", "foo", "[^x]*")
-	f(t, "foo[x]*bar", "foo", "x*bar")
-	f(t, "fo\\Bo[x]*bar?", "fo", "\\Box*bar?")
-	f(t, "foo.+bar", "foo", "(?-s:.)+bar")
-	f(t, "a(b|c.*).+", "a", "(?:b|c(?-s:.)*)(?-s:.)+")
-	f(t, "ab|ac", "a", "[b-c]")
-	f(t, "(?i)xyz", "", "(?i:XYZ)")
-	f(t, "(?i)foo|bar", "", "(?i:FOO)|(?i:BAR)")
-	f(t, "(?i)up.+x", "", "(?i:UP)(?-s:.)+(?i:X)")
-	f(t, "(?smi)xy.*z$", "", "(?i:XY)(?s:.)*(?i:Z)(?m:$)")
+	f("", "", "")
+	f("^", "", "")
+	f("$", "", "")
+	f("^()$", "", "")
+	f("^(?:)$", "", "")
+	f("foobar", "foobar", "")
+	f("foo$|^foobar", "foo", "|bar")
+	f("^(foo$|^foobar)$", "foo", "|bar")
+	f("foobar|foobaz", "fooba", "[rz]")
+	f("(fo|(zar|bazz)|x)", "", "fo|zar|bazz|x")
+	f("(тестЧЧ|тест)", "тест", "ЧЧ|")
+	f("foo(bar|baz|bana)", "fooba", "[rz]|na")
+	f("^foobar|foobaz", "fooba", "[rz]")
+	f("^foobar|^foobaz$", "fooba", "[rz]")
+	f("foobar|foobaz", "fooba", "[rz]")
+	f("(?:^foobar|^foobaz)aa.*", "fooba", "[rz]aa.*")
+	f("foo[bar]+", "foo", "[a-br]+")
+	f("foo[a-z]+", "foo", "[a-z]+")
+	f("foo[bar]*", "foo", "[a-br]*")
+	f("foo[a-z]*", "foo", "[a-z]*")
+	f("foo[x]+", "foo", "x+")
+	f("foo[^x]+", "foo", "[^x]+")
+	f("foo[x]*", "foo", "x*")
+	f("foo[^x]*", "foo", "[^x]*")
+	f("foo[x]*bar", "foo", "x*bar")
+	f("fo\\Bo[x]*bar?", "fo", "\\Box*bar?")
+	f("foo.+bar", "foo", ".+bar")
+	f("a(b|c.*).+", "a", "(?:b|c.*).+")
+	f("ab|ac", "a", "[b-c]")
+	f("(?i)xyz", "", "(?i:XYZ)")
+	f("(?i)foo|bar", "", "(?i:FOO)|(?i:BAR)")
+	f("(?i)up.+x", "", "(?i:UP).+(?i:X)")
+	f("(?smi)xy.*z$", "", "(?i:XY)(?s:.)*(?i:Z)(?m:$)")
 
 	// test invalid regexps
-	f(t, "a(", "a(", "")
-	f(t, "a[", "a[", "")
-	f(t, "a[]", "a[]", "")
-	f(t, "a{", "a{", "")
-	f(t, "a{}", "a{}", "")
-	f(t, "invalid(regexp", "invalid(regexp", "")
+	f("a(", "a(", "")
+	f("a[", "a[", "")
+	f("a[]", "a[]", "")
+	f("a{", "a{", "")
+	f("a{}", "a{}", "")
+	f("invalid(regexp", "invalid(regexp", "")
 
 	// The transformed regexp mustn't match aba
-	f(t, "a?(^ba|c)", "", "a?(?:\\Aba|c)")
+	f("a?(^ba|c)", "", "a?(?:\\Aba|c)")
 
 	// The transformed regexp mustn't match barx
-	f(t, "(foo|bar$)x*", "", "(?:foo|bar(?-m:$))x*")
+	f("(foo|bar$)x*", "", "(?:foo|bar$)x*")
 }
 
 func TestTagFiltersString(t *testing.T) {

lib/storage/tag_filters_timing_test.go

@@ -32,6 +32,29 @@ func BenchmarkTagFilterMatchSuffix(b *testing.B) {
 			}
 		})
 	})
+	b.Run("regexp-any-suffix-match-anchored", func(b *testing.B) {
+		key := []byte("^foo.*$")
+		isNegative := false
+		isRegexp := true
+		suffix := marshalTagValue(nil, []byte("ojksdfds"))
+		b.ReportAllocs()
+		b.SetBytes(int64(1))
+		b.RunParallel(func(pb *testing.PB) {
+			var tf tagFilter
+			if err := tf.Init(nil, nil, key, isNegative, isRegexp); err != nil {
+				logger.Panicf("BUG: unexpected error: %s", err)
+			}
+			for pb.Next() {
+				ok, err := tf.matchSuffix(suffix)
+				if err != nil {
+					logger.Panicf("BUG: unexpected error: %s", err)
+				}
+				if !ok {
+					logger.Panicf("BUG: unexpected suffix mismatch")
+				}
+			}
+		})
+	})
 	b.Run("regexp-any-nonzero-suffix-match", func(b *testing.B) {
 		key := []byte("foo.+")
 		isNegative := false
@@ -55,6 +78,29 @@ func BenchmarkTagFilterMatchSuffix(b *testing.B) {
 			}
 		})
 	})
+	b.Run("regexp-any-nonzero-suffix-match-anchored", func(b *testing.B) {
+		key := []byte("^foo.+$")
+		isNegative := false
+		isRegexp := true
+		suffix := marshalTagValue(nil, []byte("ojksdfds"))
+		b.ReportAllocs()
+		b.SetBytes(int64(1))
+		b.RunParallel(func(pb *testing.PB) {
+			var tf tagFilter
+			if err := tf.Init(nil, nil, key, isNegative, isRegexp); err != nil {
+				logger.Panicf("BUG: unexpected error: %s", err)
+			}
+			for pb.Next() {
+				ok, err := tf.matchSuffix(suffix)
+				if err != nil {
+					logger.Panicf("BUG: unexpected error: %s", err)
+				}
+				if !ok {
+					logger.Panicf("BUG: unexpected suffix mismatch")
+				}
+			}
+		})
+	})
 	b.Run("regexp-any-nonzero-suffix-mismatch", func(b *testing.B) {
 		key := []byte("foo.+")
 		isNegative := false