eskip: improve lexer performance (#2755)

* eskip: use larger predicate for BenchmarkParsePredicates Signed-off-by: Alexander Yastrebov <[email protected]> * eskip: optimize lexer performance * do not use fmt.Sprintf in ParseFilters and ParsePredicates * avoid allocations for fixed tokens * optimize scanWhile loop * add scanEscaped fast path * optimize scanRegexp and scanEscaped using strings.Builder * optimize scanWhitespace * optimize selectScanner using switch ``` goos: linux goarch: amd64 pkg: github.com/zalando/skipper/eskip cpu: Intel(R) Core(TM) i5-8350U CPU @ 1.70GHz │ HEAD~1 │ HEAD │ │ sec/op │ sec/op vs base │ ParsePredicates-8 29.88µ ± 3% 11.33µ ± 2% -62.09% (p=0.000 n=10) │ HEAD~1 │ HEAD │ │ B/op │ B/op vs base │ ParsePredicates-8 4.863Ki ± 0% 2.008Ki ± 0% -58.71% (p=0.000 n=10) │ HEAD~1 │ HEAD │ │ allocs/op │ allocs/op vs base │ ParsePredicates-8 198.00 ± 0% 33.00 ± 0% -83.33% (p=0.000 n=10) ``` Signed-off-by: Alexander Yastrebov <[email protected]> --------- Signed-off-by: Alexander Yastrebov <[email protected]>
zalando · Jan 16, 2024 · d468a59 · d468a59
1 parent e44f2b8
commit d468a59
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Showing 3 changed files with 150 additions and 162 deletions.
diff --git a/eskip/eskip.go b/eskip/eskip.go
@@ -616,25 +616,6 @@ func parse(code string) ([]*parsedRoute, error) {
 	return lp.lexer.routes, lp.lexer.err
 }
 
-func partialRouteToRoute(format, p string) string {
-	p = strings.TrimSpace(p)
-	if p == "" {
-		return ""
-	}
-
-	return fmt.Sprintf(format, p)
-}
-
-// hacks a filter expression into a route expression for parsing.
-func filtersToRoute(f string) string {
-	return partialRouteToRoute("* -> %s -> <shunt>", f)
-}
-
-// hacks a predicate expression into a route expression for parsing.
-func predicatesToRoute(p string) string {
-	return partialRouteToRoute("%s -> <shunt>", p)
-}
-
 // Parses a route expression or a routing document to a set of route definitions.
 func Parse(code string) ([]*Route, error) {
 	parsedRoutes, err := parse(code)
@@ -685,43 +666,44 @@ func MustParseFilters(s string) []*Filter {
 	return p
 }
 
-func partialParse(f string, partialToRoute func(string) string) (*parsedRoute, error) {
-	rs, err := parse(partialToRoute(f))
-	if err != nil {
-		return nil, err
-	}
-
-	if len(rs) == 0 {
+// Parses a filter chain into a list of parsed filter definitions.
+func ParseFilters(f string) ([]*Filter, error) {
+	f = strings.TrimSpace(f)
+	if f == "" {
 		return nil, nil
 	}
 
-	return rs[0], nil
-}
-
-// Parses a filter chain into a list of parsed filter definitions.
-func ParseFilters(f string) ([]*Filter, error) {
-	r, err := partialParse(f, filtersToRoute)
-	if r == nil || err != nil {
+	rs, err := parse("* -> " + f + " -> <shunt>")
+	if err != nil {
 		return nil, err
 	}
 
-	return r.filters, nil
+	return rs[0].filters, nil
 }
 
 // ParsePredicates parses a set of predicates (combined by '&&') into
 // a list of parsed predicate definitions.
 func ParsePredicates(p string) ([]*Predicate, error) {
-	r, err := partialParse(p, predicatesToRoute)
-	if r == nil || err != nil {
+	p = strings.TrimSpace(p)
+	if p == "" {
+		return nil, nil
+	}
+
+	rs, err := parse(p + " -> <shunt>")
+	if err != nil {
 		return nil, err
 	}
 
+	if len(rs) == 0 {
+		return nil, nil
+	}
+
 	var ps []*Predicate
-	for i := range r.matchers {
-		if r.matchers[i].name != "*" {
+	for _, matcher := range rs[0].matchers {
+		if matcher.name != "*" {
 			ps = append(ps, &Predicate{
-				Name: r.matchers[i].name,
-				Args: r.matchers[i].args,
+				Name: matcher.name,
+				Args: matcher.args,
 			})
 		}
 	}

diff --git a/eskip/eskip_test.go b/eskip/eskip_test.go
@@ -9,6 +9,7 @@ import (
 )
 
 func checkItems(t *testing.T, message string, l, lenExpected int, checkItem func(int) bool) bool {
+	t.Helper()
 	if l != lenExpected {
 		t.Error(message, "length", l, lenExpected)
 		return false
@@ -25,6 +26,7 @@ func checkItems(t *testing.T, message string, l, lenExpected int, checkItem func
 }
 
 func checkFilters(t *testing.T, message string, fs, fsExp []*Filter) bool {
+	t.Helper()
 	return checkItems(t, "filters "+message,
 		len(fs),
 		len(fsExp),
@@ -823,7 +825,18 @@ func TestFilterString(t *testing.T) {
 }
 
 func BenchmarkParsePredicates(b *testing.B) {
-	doc := `Foo("bar", "baz")`
+	doc := `FooBarBazKeyValues(
+		"https://example.org/foo0", "foobarbaz0",
+		"https://example.org/foo1", "foobarbaz1",
+		"https://example.org/foo2", "foobarbaz2",
+		"https://example.org/foo3", "foobarbaz3",
+		"https://example.org/foo4", "foobarbaz4",
+		"https://example.org/foo5", "foobarbaz5",
+		"https://example.org/foo6", "foobarbaz6",
+		"https://example.org/foo7", "foobarbaz7",
+		"https://example.org/foo8", "foobarbaz8",
+		"https://example.org/foo9", "foobarbaz9")`
+
 	_, err := ParsePredicates(doc)
 	if err != nil {
 		b.Fatal(err)