9 files changed, 117 insertions, 17 deletions

diff --git a/common/hreflect/helpers.go b/common/hreflect/helpers.go
index beab182bb..7087a9677 100644
--- a/common/hreflect/helpers.go
+++ b/common/hreflect/helpers.go
@@ -19,6 +19,7 @@ package hreflect
 import (
 	"context"
 	"reflect"
+	"sync"
 
 	"github.com/gohugoio/hugo/common/types"
 )
@@ -115,6 +116,58 @@ func IsTruthfulValue(val reflect.Value) (truth bool) {
 	return
 }
 
+type methodKey struct {
+	typ  reflect.Type
+	name string
+}
+
+type methods struct {
+	sync.RWMutex
+	cache map[methodKey]int
+}
+
+var methodCache = &methods{cache: make(map[methodKey]int)}
+
+// GetMethodByName is the samve as reflect.Value.MethodByName, but it caches the
+// type lookup.
+func GetMethodByName(v reflect.Value, name string) reflect.Value {
+	index := GetMethodIndexByName(v.Type(), name)
+
+	if index == -1 {
+		return reflect.Value{}
+	}
+
+	return v.Method(index)
+}
+
+// GetMethodIndexByName returns the index of the method with the given name, or
+// -1 if no such method exists.
+func GetMethodIndexByName(tp reflect.Type, name string) int {
+	k := methodKey{tp, name}
+	methodCache.RLock()
+	index, found := methodCache.cache[k]
+	methodCache.RUnlock()
+	if found {
+		return index
+	}
+
+	methodCache.Lock()
+	defer methodCache.Unlock()
+
+	m, ok := tp.MethodByName(name)
+	index = m.Index
+	if !ok {
+		index = -1
+	}
+	methodCache.cache[k] = index
+
+	if !ok {
+		return -1
+	}
+
+	return m.Index
+}
+
 // Based on: https://github.com/golang/go/blob/178a2c42254166cffed1b25fb1d3c7a5727cada6/src/text/template/exec.go#L931
 func indirectInterface(v reflect.Value) reflect.Value {
 	if v.Kind() != reflect.Interface {
diff --git a/common/hreflect/helpers_test.go b/common/hreflect/helpers_test.go
index 480ccb27a..d16b9b9b3 100644
--- a/common/hreflect/helpers_test.go
+++ b/common/hreflect/helpers_test.go
@@ -30,6 +30,16 @@ func TestIsTruthful(t *testing.T) {
 	c.Assert(IsTruthful(time.Time{}), qt.Equals, false)
 }
 
+func TestGetMethodByName(t *testing.T) {
+	c := qt.New(t)
+	v := reflect.ValueOf(&testStruct{})
+	tp := v.Type()
+
+	c.Assert(GetMethodIndexByName(tp, "Method1"), qt.Equals, 0)
+	c.Assert(GetMethodIndexByName(tp, "Method3"), qt.Equals, 2)
+	c.Assert(GetMethodIndexByName(tp, "Foo"), qt.Equals, -1)
+}
+
 func BenchmarkIsTruthFul(b *testing.B) {
 	v := reflect.ValueOf("Hugo")
 
@@ -40,3 +50,37 @@ func BenchmarkIsTruthFul(b *testing.B) {
 		}
 	}
 }
+
+type testStruct struct{}
+
+func (t *testStruct) Method1() string {
+	return "Hugo"
+}
+
+func (t *testStruct) Method2() string {
+	return "Hugo"
+}
+
+func (t *testStruct) Method3() string {
+	return "Hugo"
+}
+
+func (t *testStruct) Method4() string {
+	return "Hugo"
+}
+
+func (t *testStruct) Method5() string {
+	return "Hugo"
+}
+
+func BenchmarkGetMethodByName(b *testing.B) {
+	v := reflect.ValueOf(&testStruct{})
+	methods := []string{"Method1", "Method2", "Method3", "Method4", "Method5"}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		for _, method := range methods {
+			_ = GetMethodByName(v, method)
+		}
+	}
+}
diff --git a/langs/i18n/i18n.go b/langs/i18n/i18n.go
index e45a16822..64340c857 100644
--- a/langs/i18n/i18n.go
+++ b/langs/i18n/i18n.go
@@ -160,7 +160,7 @@ func getPluralCount(v interface{}) interface{} {
 			if f.IsValid() {
 				return toPluralCountValue(f.Interface())
 			}
-			m := vv.MethodByName(countFieldName)
+			m := hreflect.GetMethodByName(vv, countFieldName)
 			if m.IsValid() && m.Type().NumIn() == 0 && m.Type().NumOut() == 1 {
 				c := m.Call(nil)
 				return toPluralCountValue(c[0].Interface())
@@ -169,7 +169,6 @@ func getPluralCount(v interface{}) interface{} {
 	}
 
 	return toPluralCountValue(v)
-
 }
 
 // go-i18n expects floats to be represented by string.
diff --git a/resources/page/pagegroup.go b/resources/page/pagegroup.go
index e07efa7ca..4c0adb68b 100644
--- a/resources/page/pagegroup.go
+++ b/resources/page/pagegroup.go
@@ -24,6 +24,7 @@ import (
 	"github.com/spf13/cast"
 
 	"github.com/gohugoio/hugo/common/collections"
+	"github.com/gohugoio/hugo/common/hreflect"
 	"github.com/gohugoio/hugo/compare"
 
 	"github.com/gohugoio/hugo/resources/resource"
@@ -112,8 +113,9 @@ func (p Pages) GroupBy(key string, order ...string) (PagesGroup, error) {
 	}
 
 	var ft interface{}
-	m, ok := pagePtrType.MethodByName(key)
-	if ok {
+	index := hreflect.GetMethodIndexByName(pagePtrType, key)
+	if index != -1 {
+		m := pagePtrType.Method(index)
 		if m.Type.NumOut() == 0 || m.Type.NumOut() > 2 {
 			return nil, errors.New(key + " is a Page method but you can't use it with GroupBy")
 		}
@@ -125,6 +127,7 @@ func (p Pages) GroupBy(key string, order ...string) (PagesGroup, error) {
 		}
 		ft = m
 	} else {
+		var ok bool
 		ft, ok = pagePtrType.Elem().FieldByName(key)
 		if !ok {
 			return nil, errors.New(key + " is neither a field nor a method of Page")
@@ -146,7 +149,7 @@ func (p Pages) GroupBy(key string, order ...string) (PagesGroup, error) {
 		case reflect.StructField:
 			fv = ppv.Elem().FieldByName(key)
 		case reflect.Method:
-			fv = ppv.MethodByName(key).Call([]reflect.Value{})[0]
+			fv = hreflect.GetMethodByName(ppv, key).Call([]reflect.Value{})[0]
 		}
 		if !fv.IsValid() {
 			continue
diff --git a/resources/postpub/postpub.go b/resources/postpub/postpub.go
index c11dda577..f1012b7da 100644
--- a/resources/postpub/postpub.go
+++ b/resources/postpub/postpub.go
@@ -21,6 +21,7 @@ import (
 
 	"github.com/spf13/cast"
 
+	"github.com/gohugoio/hugo/common/hreflect"
 	"github.com/gohugoio/hugo/common/maps"
 	"github.com/gohugoio/hugo/media"
 	"github.com/gohugoio/hugo/resources/resource"
@@ -125,7 +126,7 @@ func (r *PostPublishResource) fieldToString(receiver interface{}, path string) s
 	default:
 		v := receiverv.FieldByName(fieldname)
 		if !v.IsValid() {
-			method := receiverv.MethodByName(fieldname)
+			method := hreflect.GetMethodByName(receiverv, fieldname)
 			if method.IsValid() {
 				vals := method.Call(nil)
 				if len(vals) > 0 {
diff --git a/tpl/collections/apply.go b/tpl/collections/apply.go
index 0833e5507..55bab5d1a 100644
--- a/tpl/collections/apply.go
+++ b/tpl/collections/apply.go
@@ -131,7 +131,7 @@ func (ns *Namespace) lookupFunc(fname string) (reflect.Value, bool) {
 	nv = reflect.ValueOf(v)
 
 	// method
-	m := nv.MethodByName(ss[1])
+	m := hreflect.GetMethodByName(nv, ss[1])
 
 	if m.Kind() == reflect.Invalid {
 		return reflect.Value{}, false
diff --git a/tpl/collections/where.go b/tpl/collections/where.go
index 8ffcf6165..ac604760d 100644
--- a/tpl/collections/where.go
+++ b/tpl/collections/where.go
@@ -19,6 +19,7 @@ import (
 	"reflect"
 	"strings"
 
+	"github.com/gohugoio/hugo/common/hreflect"
 	"github.com/gohugoio/hugo/common/maps"
 )
 
@@ -300,8 +301,9 @@ func evaluateSubElem(obj reflect.Value, elemName string) (reflect.Value, error)
 		objPtr = objPtr.Addr()
 	}
 
-	mt, ok := objPtr.Type().MethodByName(elemName)
-	if ok {
+	index := hreflect.GetMethodIndexByName(objPtr.Type(), elemName)
+	if index != -1 {
+		mt := objPtr.Type().Method(index)
 		switch {
 		case mt.PkgPath != "":
 			return zero, fmt.Errorf("%s is an unexported method of type %s", elemName, typ)
@@ -513,5 +515,5 @@ func toTimeUnix(v reflect.Value) int64 {
 	if v.Type() != timeType {
 		panic("coding error: argument must be time.Time type reflect Value")
 	}
-	return v.MethodByName("Unix").Call([]reflect.Value{})[0].Int()
+	return hreflect.GetMethodByName(v, "Unix").Call([]reflect.Value{})[0].Int()
 }
diff --git a/tpl/internal/go_templates/texttemplate/hugo_template_test.go b/tpl/internal/go_templates/texttemplate/hugo_template_test.go
index 150802bf4..cc88151e3 100644
--- a/tpl/internal/go_templates/texttemplate/hugo_template_test.go
+++ b/tpl/internal/go_templates/texttemplate/hugo_template_test.go
@@ -21,6 +21,7 @@ import (
 	"testing"
 
 	qt "github.com/frankban/quicktest"
+	"github.com/gohugoio/hugo/common/hreflect"
 )
 
 type TestStruct struct {
@@ -59,7 +60,7 @@ func (e *execHelper) GetMethod(ctx context.Context, tmpl Preparer, receiver refl
 	if name != "Hello1" {
 		return zero, zero
 	}
-	m := receiver.MethodByName("Hello2")
+	m := hreflect.GetMethodByName(receiver, "Hello2")
 	return m, reflect.ValueOf("v2")
 }
 
diff --git a/tpl/tplimpl/template_funcs.go b/tpl/tplimpl/template_funcs.go
index 8692b9ee2..0ecd5df46 100644
--- a/tpl/tplimpl/template_funcs.go
+++ b/tpl/tplimpl/template_funcs.go
@@ -20,9 +20,9 @@ import (
 	"reflect"
 	"strings"
 
-	"github.com/gohugoio/hugo/tpl"
-
+	"github.com/gohugoio/hugo/common/hreflect"
 	"github.com/gohugoio/hugo/common/maps"
+	"github.com/gohugoio/hugo/tpl"
 
 	template "github.com/gohugoio/hugo/tpl/internal/go_templates/htmltemplate"
 	texttemplate "github.com/gohugoio/hugo/tpl/internal/go_templates/texttemplate"
@@ -111,9 +111,6 @@ func (t *templateExecHelper) GetMapValue(ctx context.Context, tmpl texttemplate.
 
 func (t *templateExecHelper) GetMethod(ctx context.Context, tmpl texttemplate.Preparer, receiver reflect.Value, name string) (method reflect.Value, firstArg reflect.Value) {
 	if t.running {
-		// This is a hot path and receiver.MethodByName really shows up in the benchmarks,
-		// so we maintain a list of method names with that signature.
-		// TODO(bep) I have a branch that makes this construct superflous.
 		switch name {
 		case "GetPage", "Render":
 			if info, ok := tmpl.(tpl.Info); ok {
@@ -124,7 +121,7 @@ func (t *templateExecHelper) GetMethod(ctx context.Context, tmpl texttemplate.Pr
 		}
 	}
 
-	fn := receiver.MethodByName(name)
+	fn := hreflect.GetMethodByName(receiver, name)
 	if !fn.IsValid() {
 		return zero, zero
 	}