Ruby: Implement Write Barrier on Message class

ruby/ext/google/protobuf_c/defs.c

@@ -223,6 +223,8 @@ static void DescriptorPool_register(VALUE module) {
 
 typedef struct {
   const upb_MessageDef* msgdef;
+// IMPORTANT: WB_PROTECTED objects must only use the RB_OBJ_WRITE()
+// macro to update VALUE references, as to trigger write barriers.
   VALUE klass;
   VALUE descriptor_pool;
 } Descriptor;
@@ -417,6 +419,8 @@ static void Descriptor_register(VALUE module) {
 
 typedef struct {
   const upb_FileDef* filedef;
+  // IMPORTANT: WB_PROTECTED objects must only use the RB_OBJ_WRITE()
+  // macro to update VALUE references, as to trigger write barriers.
   VALUE descriptor_pool;  // Owns the upb_FileDef.
 } FileDescriptor;
 
@@ -519,6 +523,8 @@ static void FileDescriptor_register(VALUE module) {
 
 typedef struct {
   const upb_FieldDef* fielddef;
+  // IMPORTANT: WB_PROTECTED objects must only use the RB_OBJ_WRITE()
+  // macro to update VALUE references, as to trigger write barriers.
   VALUE descriptor_pool;  // Owns the upb_FieldDef.
 } FieldDescriptor;
 
@@ -884,6 +890,8 @@ static void FieldDescriptor_register(VALUE module) {
 
 typedef struct {
   const upb_OneofDef* oneofdef;
+  // IMPORTANT: WB_PROTECTED objects must only use the RB_OBJ_WRITE()
+  // macro to update VALUE references, as to trigger write barriers.
   VALUE descriptor_pool;  // Owns the upb_OneofDef.
 } OneofDescriptor;
 
@@ -988,6 +996,8 @@ static void OneofDescriptor_register(VALUE module) {
 
 typedef struct {
   const upb_EnumDef* enumdef;
+  // IMPORTANT: WB_PROTECTED objects must only use the RB_OBJ_WRITE()
+  // macro to update VALUE references, as to trigger write barriers.
   VALUE module;           // begins as nil
   VALUE descriptor_pool;  // Owns the upb_EnumDef.
 } EnumDescriptor;

ruby/ext/google/protobuf_c/message.c

@@ -53,6 +53,8 @@ VALUE MessageOrEnum_GetDescriptor(VALUE klass) {
 // -----------------------------------------------------------------------------
 
 typedef struct {
+  // IMPORTANT: WB_PROTECTED objects must only use the RB_OBJ_WRITE()
+  // macro to update VALUE references, as to trigger write barriers.
   VALUE arena;
   const upb_Message* msg;  // Can get as mutable when non-frozen.
   const upb_MessageDef*
@@ -65,9 +67,9 @@ static void Message_mark(void* _self) {
 }
 
 static rb_data_type_t Message_type = {
-    "Message",
+    "Google::Protobuf::Message",
     {Message_mark, RUBY_DEFAULT_FREE, NULL},
-    .flags = RUBY_TYPED_FREE_IMMEDIATELY,
+    .flags = RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED,
 };
 
 static Message* ruby_to_Message(VALUE msg_rb) {
@@ -105,7 +107,7 @@ upb_Message* Message_GetMutable(VALUE msg_rb, const upb_MessageDef** m) {
 void Message_InitPtr(VALUE self_, upb_Message* msg, VALUE arena) {
   Message* self = ruby_to_Message(self_);
   self->msg = msg;
-  self->arena = arena;
+  RB_OBJ_WRITE(self_, &self->arena, arena);
   ObjectCache_Add(msg, self_);
 }
 

ruby/ext/google/protobuf_c/protobuf.c

@@ -171,6 +171,8 @@ void StringBuilder_PrintMsgval(StringBuilder *b, upb_MessageValue val,
 
 typedef struct {
   upb_Arena *arena;
+  // IMPORTANT: WB_PROTECTED objects must only use the RB_OBJ_WRITE()
+  // macro to update VALUE references, as to trigger write barriers.
   VALUE pinned_objs;
 } Arena;