reduce allocations.

Author: joeybloggs

decoder.go

@@ -68,9 +68,8 @@ func (d *decoder) parseMapData() {
 			cidx2 = cum + idx2
 
 			if rd, ok = d.dm[k[:cidx]]; !ok {
-				rd = &recursiveData{
-					keys: make([]key, 0, 8), // initializing with initial capacity of 8 to avoid too many reallocations of the underlying array
-				}
+				rd = d.d.keyPool.Get().(*recursiveData)
+				rd.keys = rd.keys[0:0]
 				d.dm[k[:cidx]] = rd
 			}
 
@@ -106,6 +105,7 @@ func (d *decoder) traverseStruct(v reflect.Value, namespace string) (set bool) {
 
 	typ := v.Type()
 	var nn string // new namespace
+	first := len(namespace) == 0
 
 	// is anonymous struct, cannot parse or cache as
 	// it has no name to index by and potentially a
@@ -132,7 +132,7 @@ func (d *decoder) traverseStruct(v reflect.Value, namespace string) (set bool) {
 				key = fld.Name
 			}
 
-			if len(namespace) == 0 {
+			if first {
 				nn = key
 			} else {
 				nn = namespace + namespaceSeparator + key
@@ -151,7 +151,7 @@ func (d *decoder) traverseStruct(v reflect.Value, namespace string) (set bool) {
 
 		for _, f := range s.fields {
 
-			if len(namespace) == 0 {
+			if first {
 				nn = f.name
 			} else {
 				nn = namespace + namespaceSeparator + f.name

form_decoder.go

@@ -5,6 +5,7 @@ import (
 	"net/url"
 	"reflect"
 	"strings"
+	"sync"
 )
 
 // DecodeCustomTypeFunc allows for registering/overriding types to be parsed.
@@ -46,6 +47,7 @@ type Decoder struct {
 	structCache     structCacheMap
 	customTypeFuncs map[reflect.Type]DecodeCustomTypeFunc
 	maxArraySize    int
+	keyPool         *sync.Pool
 }
 
 // NewDecoder creates a new decoder instance with sane defaults
@@ -54,6 +56,11 @@ func NewDecoder() *Decoder {
 		tagName:      "form",
 		structCache:  structCacheMap{m: map[reflect.Type]cachedStruct{}},
 		maxArraySize: 10000,
+		keyPool: &sync.Pool{New: func() interface{} {
+			return &recursiveData{
+				keys: make([]key, 0, 8), // initializing with initial capacity of 8 to avoid too many reallocations of the underlying array
+			}
+		}},
 	}
 }
 
@@ -141,6 +148,10 @@ func (d *Decoder) Decode(v interface{}, values url.Values) (err error) {
 
 	dec.traverseStruct(val, "")
 
+	for _, v := range dec.dm {
+		d.keyPool.Put(v)
+	}
+
 	if len(dec.errs) == 0 {
 		return nil
 	}