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author | Felix Lange <fjl@twurst.com> | 2014-11-14 03:31:48 +0800 |
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committer | Felix Lange <fjl@twurst.com> | 2014-11-17 08:49:47 +0800 |
commit | 74266d5bbd95ac07882b09230aec876bf7704f69 (patch) | |
tree | 101cd83defc7d396f42500bbf080243fb8571acf /rlp/typecache.go | |
parent | 9509322ecd8e709ce8a17442836b6ff15ba2edff (diff) | |
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rlp: new package for streaming RLP decoder
Diffstat (limited to 'rlp/typecache.go')
-rw-r--r-- | rlp/typecache.go | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/rlp/typecache.go b/rlp/typecache.go new file mode 100644 index 000000000..75dbb43c2 --- /dev/null +++ b/rlp/typecache.go @@ -0,0 +1,91 @@ +package rlp + +import ( + "fmt" + "math/big" + "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 +} + +var ( + decoderInterface = reflect.TypeOf(new(Decoder)).Elem() + bigInt = reflect.TypeOf(big.Int{}) +) + +func genTypeInfo(typ reflect.Type) (info *typeinfo, err error) { + info = new(typeinfo) + kind := typ.Kind() + switch { + case typ.Implements(decoderInterface): + info.decoder = decodeDecoder + case kind != reflect.Ptr && reflect.PtrTo(typ).Implements(decoderInterface): + info.decoder = decodeDecoderNoPtr + case typ.AssignableTo(reflect.PtrTo(bigInt)): + info.decoder = decodeBigInt + case typ.AssignableTo(bigInt): + info.decoder = decodeBigIntNoPtr + case isInteger(kind): + info.decoder = makeNumDecoder(typ) + case kind == reflect.String: + info.decoder = decodeString + case kind == reflect.Slice || kind == reflect.Array: + info.decoder, err = makeListDecoder(typ) + case kind == reflect.Struct: + info.decoder, err = makeStructDecoder(typ) + case kind == reflect.Ptr: + info.decoder, err = makePtrDecoder(typ) + case kind == reflect.Interface && typ.NumMethod() == 0: + info.decoder = decodeInterface + default: + err = fmt.Errorf("rlp: type %v is not RLP-serializable", typ) + } + return info, err +} + +func isInteger(k reflect.Kind) bool { + return k >= reflect.Int && k <= reflect.Uintptr +} |