[wasm] Skeleton WasmModuleObjectBuilder for streamed compilation

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index d2f19e07119428850900738afa58525f75b8ace4..66bd22053649b689e0d8f8333bb9b060bcb55a38 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -3914,6 +3914,8 @@ class V8_EXPORT Proxy : public Object {
   static void CheckCast(Value* obj);
 };
 
+// TODO(mtrofin): rename WasmCompiledModule to WasmModuleObject, for

[clemensh, 2017/03/27 07:39:20]

FYI: Ben once had the plan to rename this to WasmSpecializedCode.
The problem with the current name (and also "WasmModuleObject") is that this
suggests that only one such object exists per module, which is not the case.

[Mircea Trofin, 2017/03/27 07:58:30]

By "module" you mean "wire bytes"?

An instance of WasmCompiledModule is the v8 wrapping of an instance of the JS
type "WebAssembly.Module".  Not sure where the problem is: the user knows they
can create multiple WebAssembly.Module objects from the same instance of wire
bytes. Same here.

+// consistency with internal APIs.
 class V8_EXPORT WasmCompiledModule : public Object {
  public:
   typedef std::pair<std::unique_ptr<const uint8_t[]>, size_t> SerializedModule;
@@ -3965,6 +3967,10 @@ class V8_EXPORT WasmCompiledModule : public Object {
   V8_INLINE static WasmCompiledModule* Cast(Value* obj);
 
  private:
+  // TODO(ahaas): please remove the friend once streamed compilation is
+  // implemented
+  friend class WasmModuleObjectBuilder;
+
   static MaybeLocal<WasmCompiledModule> Deserialize(
       Isolate* isolate, const CallerOwnedBuffer& serialized_module,
       const CallerOwnedBuffer& wire_bytes);
@@ -3980,6 +3986,29 @@ class V8_EXPORT WasmCompiledModule : public Object {
   static void CheckCast(Value* obj);
 };
 
+class V8_EXPORT WasmModuleObjectBuilder final {
+ public:
+  WasmModuleObjectBuilder(Isolate* isolate) : isolate_(isolate) {}
+  void OnBytesReceived(std::unique_ptr<const uint8_t[]>&& bytes, size_t size);
+  MaybeLocal<WasmCompiledModule> Finish();
+
+ private:
+  Isolate* isolate_ = nullptr;
+  // TODO(ahaas): We probably need none of this below here once streamed
+  // compilation is implemented.
+  typedef std::pair<std::unique_ptr<const uint8_t[]>, size_t> Buffer;
+
+  // Disable copy semantics *in this implementation*. We can choose to
+  // relax this, albeit it's not clear why.
+  WasmModuleObjectBuilder(const WasmModuleObjectBuilder&) = delete;
+  WasmModuleObjectBuilder(WasmModuleObjectBuilder&&) = default;
+  WasmModuleObjectBuilder& operator=(const WasmModuleObjectBuilder&) = delete;
+  WasmModuleObjectBuilder& operator=(WasmModuleObjectBuilder&&) = default;
+
+  std::vector<Buffer> received_buffers_;
+  size_t total_size_ = 0;
+};
+
 #ifndef V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT
 // The number of required internal fields can be defined by embedder.
 #define V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT 2