Merge pull request #52 from restatedev/issue-51

Add comment about deterministic marshaling

encoding/encoding.go

@@ -75,13 +75,15 @@ func OutputPayloadFor(codec PayloadCodec, o any) *OutputPayload {
 }
 
 // RestateMarshaler can be implemented by types that want to control their own marshaling
+// Marshaling *must* be deterministic
 type RestateMarshaler interface {
 	RestateMarshal(codec Codec) ([]byte, error)
 	OutputPayload(codec Codec) *OutputPayload
 }
 
 // Codec is a mechanism for serialising and deserialising a wide range of types.
 // Care should be taken to ensure that only valid types are passed to a codec, eg proto.Message for [ProtoCodec].
+// Codecs *must* marshal deterministically, such that a round trip of []byte -> any -> []byte leaves the bytes unchanged.
 type Codec interface {
 	Marshal(v any) ([]byte, error)
 	Unmarshal(data []byte, v any) error