Add faster key for type cache

This change was copy-pasted from:

 * https://groups.google.com/forum/#!topic/golang-dev/Oik3353DJ2w
 * https://github.com/ugorji/go/blob/54210f4e076c57f351166f0ed60e67d3fca57a36/codec/helper_unsafe.go#L9

bson/bson.go

@@ -634,7 +634,7 @@ type fieldInfo struct {
 	Inline    []int
 }
 
-var structMap = make(map[reflect.Type]*structInfo)
+var structMap = make(map[typeID]*structInfo)
 var structMapMutex sync.RWMutex
 
 type externalPanic string
@@ -645,7 +645,8 @@ func (e externalPanic) String() string {
 
 func getStructInfo(st reflect.Type) (*structInfo, error) {
 	structMapMutex.RLock()
-	sinfo, found := structMap[st]
+	key := rt2id(st)
+	sinfo, found := structMap[key]
 	structMapMutex.RUnlock()
 	if found {
 		return sinfo, nil
@@ -744,7 +745,7 @@ func getStructInfo(st reflect.Type) (*structInfo, error) {
 		reflect.New(st).Elem(),
 	}
 	structMapMutex.Lock()
-	structMap[st] = sinfo
+	structMap[key] = sinfo
 	structMapMutex.Unlock()
 	return sinfo, nil
 }

bson/decode.go

@@ -73,31 +73,32 @@ const (
 	setterAddr
 )
 
-var setterStyles map[reflect.Type]int
+var setterStyles map[typeID]int
 var setterIface reflect.Type
 var setterMutex sync.RWMutex
 
 func init() {
 	var iface Setter
 	setterIface = reflect.TypeOf(&iface).Elem()
-	setterStyles = make(map[reflect.Type]int)
+	setterStyles = make(map[typeID]int)
 }
 
 func setterStyle(outt reflect.Type) int {
+	key := rt2id(outt)
 	setterMutex.RLock()
-	style := setterStyles[outt]
+	style := setterStyles[key]
 	setterMutex.RUnlock()
 	if style == setterUnknown {
 		setterMutex.Lock()
 		defer setterMutex.Unlock()
 		if outt.Implements(setterIface) {
-			setterStyles[outt] = setterType
+			setterStyles[key] = setterType
 		} else if reflect.PtrTo(outt).Implements(setterIface) {
-			setterStyles[outt] = setterAddr
+			setterStyles[key] = setterAddr
 		} else {
-			setterStyles[outt] = setterNone
+			setterStyles[key] = setterNone
 		}
-		style = setterStyles[outt]
+		style = setterStyles[key]
 	}
 	return style
 }

bson/encode.go

@@ -71,7 +71,7 @@ const (
 
 var itoaCache []string
 
-var getterStyles map[reflect.Type]int
+var getterStyles map[typeID]int
 var getterIface reflect.Type
 var getterMutex sync.RWMutex
 
@@ -82,7 +82,7 @@ func init() {
 	}
 	var iface Getter
 	getterIface = reflect.TypeOf(&iface).Elem()
-	getterStyles = make(map[reflect.Type]int)
+	getterStyles = make(map[typeID]int)
 }
 
 func itoa(i int) string {
@@ -93,8 +93,9 @@ func itoa(i int) string {
 }
 
 func getterStyle(outt reflect.Type) int {
+	key := rt2id(outt)
 	getterMutex.RLock()
-	style := getterStyles[outt]
+	style := getterStyles[key]
 	getterMutex.RUnlock()
 	if style == getterUnknown {
 		getterMutex.Lock()
@@ -105,16 +106,16 @@ func getterStyle(outt reflect.Type) int {
 				vt = vt.Elem()
 			}
 			if vt.Implements(getterIface) {
-				getterStyles[outt] = getterTypeVal
+				getterStyles[key] = getterTypeVal
 			} else {
-				getterStyles[outt] = getterTypePtr
+				getterStyles[key] = getterTypePtr
 			}
 		} else if reflect.PtrTo(outt).Implements(getterIface) {
-			getterStyles[outt] = getterAddr
+			getterStyles[key] = getterAddr
 		} else {
-			getterStyles[outt] = getterNone
+			getterStyles[key] = getterNone
 		}
-		style = getterStyles[outt]
+		style = getterStyles[key]
 	}
 	return style
 }
@@ -391,7 +392,7 @@ func (e *encoder) addElem(name string, v reflect.Value, minSize bool) {
 			// Stored as int64
 			e.addElemName(0x12, name)
 
-			e.addInt64(int64(v.Int()/1e6))
+			e.addInt64(int64(v.Int() / 1e6))
 		default:
 			i := v.Int()
 			if (minSize || v.Type().Kind() != reflect.Int64) && i >= math.MinInt32 && i <= math.MaxInt32 {

bson/helper_safe.go

@@ -0,0 +1,13 @@
+// +build !go1.7 safe appengine
+
+package bson
+
+import (
+	"reflect"
+)
+
+type typeID uintptr
+
+func rt2id(rt reflect.Type) typeID {
+	return typeID(reflect.ValueOf(rt).Pointer())
+}

bson/helper_unsafe.go

@@ -0,0 +1,21 @@
+// +build !safe
+// +build !appengine
+// +build go1.7
+
+package bson
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+type typeID uintptr
+
+type unsafeIntf struct {
+	typ  unsafe.Pointer
+	word unsafe.Pointer
+}
+
+func rt2id(rt reflect.Type) typeID {
+	return typeID(((*unsafeIntf)(unsafe.Pointer(&rt))).word)
+}