1 files changed, 62 insertions, 0 deletions
diff --git a/rlp/typecache.go b/rlp/typecache.go
new file mode 100644
index 000000000..52e68a3c5
--- /dev/null
+++ b/rlp/typecache.go
@@ -0,0 +1,62 @@
+package rlp
+
+import (
+	"reflect"
+	"sync"
+)
+
+type decoder func(*Stream, reflect.Value) error
+
+type typeinfo struct {
+	decoder
+}
+
+var (
+	typeCacheMutex sync.RWMutex
+	typeCache      = make(map[reflect.Type]*typeinfo)
+)
+
+func cachedTypeInfo(typ reflect.Type) (*typeinfo, error) {
+	typeCacheMutex.RLock()
+	info := typeCache[typ]
+	typeCacheMutex.RUnlock()
+	if info != nil {
+		return info, nil
+	}
+	// not in the cache, need to generate info for this type.
+	typeCacheMutex.Lock()
+	defer typeCacheMutex.Unlock()
+	return cachedTypeInfo1(typ)
+}
+
+func cachedTypeInfo1(typ reflect.Type) (*typeinfo, error) {
+	info := typeCache[typ]
+	if info != nil {
+		// another goroutine got the write lock first
+		return info, nil
+	}
+	// put a dummmy value into the cache before generating.
+	// if the generator tries to lookup itself, it will get
+	// the dummy value and won't call itself recursively.
+	typeCache[typ] = new(typeinfo)
+	info, err := genTypeInfo(typ)
+	if err != nil {
+		// remove the dummy value if the generator fails
+		delete(typeCache, typ)
+		return nil, err
+	}
+	*typeCache[typ] = *info
+	return typeCache[typ], err
+}
+
+func genTypeInfo(typ reflect.Type) (info *typeinfo, err error) {
+	info = new(typeinfo)
+	if info.decoder, err = makeDecoder(typ); err != nil {
+		return nil, err
+	}
+	return info, nil
+}
+
+func isUint(k reflect.Kind) bool {
+	return k >= reflect.Uint && k <= reflect.Uintptr
+}