Begin implementing V8 bindings for Mojo

mojo/public/bindings/js/v8_core.cc

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "mojo/public/bindings/js/v8_core.h"
+
+#include "mojo/public/bindings/js/v8_array_buffer.h"
+#include "mojo/public/bindings/js/v8_conversions.h"
+#include "mojo/public/bindings/js/v8_exceptions.h"
+#include "mojo/public/bindings/js/v8_per_isolate_data.h"
+
+namespace mojo {
+namespace js {
+
+namespace {
+
+static WrapperInfo g_handle_wrapper_info = {};

[Aaron Boodman, 2013/11/09 08:26:02]

We aren't supposed to have non-primitive static data in normal Chrome code. Do
we want to follow the same rule here?

[abarth-chromium, 2013/11/09 08:52:37]

WrapperInfo is POD.  It doesn't have any static initializers or anything.  If
that's against Chromium style, I can find another way to handle this situation.

[Aaron Boodman, 2013/11/09 21:12:12]

It seems like that should be OK logically, but I vaguely remember mpcomplete
arguing against any non-primitive types. Ask darin or trung? I'll go with
whatever one of them says.

+
+bool ToHandleArray(v8::Isolate* isolate,
+                   v8::Handle<v8::Value> value,
+                   std::vector<mojo::Handle>* handles) {
+  if (!value->IsArray()) {

[Aaron Boodman, 2013/11/09 08:26:02]

It seems like Wrapper<std::vector<mojo::Handle>> should do all this and this
extra function shouldn't be needed.

The only question is the error messages. I would just say to collapse both 
cases into "invalid value - expected array of mojo::Handles".

[abarth-chromium, 2013/11/09 08:52:37]

Good point.

+    ThrowTypeError(isolate, "Expected array argument.");
+    return false;
+  }
+  if (!ToNativeArray(v8::Handle<v8::Array>::Cast(value), handles)) {
+    ThrowTypeError(isolate, "Expected an array of mojo::Handles.");
+    return false;
+  }
+  return true;
+}
+
+void CloseCallback(const v8::FunctionCallbackInfo<v8::Value>& info) {

[Aaron Boodman, 2013/11/09 08:26:02]

I think the term 'callback' here is confusing because we frequently use terms
like 'FooCallback' to mean 'the code that should be called after the async
process "foo" is done'.

Maybe just Close? or CloseImpl?

[abarth-chromium, 2013/11/09 08:52:37]

Sorry, that's terminology from the Blink bindings leaking in.  I'll change this
to Close.  We'll still be able to call the Close from core.h because it's in a
different namespace.

+  v8::Isolate* isolate = info.GetIsolate();
+  mojo::Handle handle = Wrapper<Handle>::ToNativeUnchecked(info.Holder());
+
+  MojoResult result = mojo::Close(handle);
+  info.GetReturnValue().Set(Wrapper<MojoResult>::ToObject(isolate, result));
+}
+
+void WaitCallback(const v8::FunctionCallbackInfo<v8::Value>& info) {
+  v8::Isolate* isolate = info.GetIsolate();
+
+  if (info.Length() < 2)

[Aaron Boodman, 2013/11/09 08:26:02]

In my experience, this kind of code quickly gets inconsistent and unruly. There
should at least be some kind of simple V8ArgumentParser object I think:

ArgumentParser parser(info);
Foo foo = parser.GetRequired<Foo>(0);
Bar bar = parser.GetOptional<Bar>(1);
if (parser.HasError()) {
  ThrowError(parser.GetErrorMessage());
  return;
}

...

[abarth-chromium, 2013/11/09 08:52:37]

Ok.  I'll work something up along those lines.

+    return ThrowTypeError(isolate, kInsufficientArguments);
+
+  mojo::Handle handle = Wrapper<Handle>::ToNativeUnchecked(info.Holder());
+  MojoWaitFlags flags = Wrapper<MojoWaitFlags>::ToNative(info[0]);
+  MojoDeadline deadline = Wrapper<MojoDeadline>::ToNative(info[1]);
+
+  MojoResult result = mojo::Wait(handle, flags, deadline);
+  info.GetReturnValue().Set(Wrapper<MojoResult>::ToObject(isolate, result));
+}
+
+void WriteMessageCallback(const v8::FunctionCallbackInfo<v8::Value>& info) {
+  v8::Isolate* isolate = info.GetIsolate();
+
+  if (info.Length() < 3)
+    return ThrowTypeError(isolate, kInsufficientArguments);
+
+  mojo::Handle handle = Wrapper<Handle>::ToNativeUnchecked(info.Holder());
+
+  if (!info[0]->IsArrayBufferView())
+    return ThrowTypeError(isolate, "Expected an ArrayBufferView.");
+  BufferView buffer(isolate, v8::Handle<v8::ArrayBufferView>::Cast(info[0]));

[Aaron Boodman, 2013/11/09 08:26:02]

It would be cool if BufferView could again have a WrapperImpl for converting to
and from JS. This would make it work with the ArgumentParser mentioned above.

[abarth-chromium, 2013/11/09 08:52:37]

Ok.  I'll have to do some more work to make BufferView copyable, but that should
be doable.

+
+  std::vector<mojo::Handle> handles;
+  if (!ToHandleArray(isolate, info[1], &handles))
+    return;
+
+  MojoWaitFlags flags = Wrapper<MojoWaitFlags>::ToNative(info[2]);
+
+  MojoResult result = mojo::WriteMessage(handle,
+                                         buffer.bytes(),
+                                         buffer.num_bytes(),
+                                         handles.data(),
+                                         handles.size(),
+                                         flags);
+
+  info.GetReturnValue().Set(Wrapper<MojoResult>::ToObject(isolate, result));
+}
+
+void ReadMessageCallback(const v8::FunctionCallbackInfo<v8::Value>& info) {
+  v8::Isolate* isolate = info.GetIsolate();
+
+  if (info.Length() < 3)
+    return ThrowTypeError(isolate, kInsufficientArguments);
+
+  mojo::Handle handle = Wrapper<Handle>::ToNativeUnchecked(info.Holder());
+
+  if (!info[0]->IsArrayBufferView())
+    return ThrowTypeError(isolate, "Expected an ArrayBufferView.");
+  BufferView buffer(isolate, v8::Handle<v8::ArrayBufferView>::Cast(info[0]));
+
+  std::vector<mojo::Handle> handles(info[1]->Uint32Value());
+
+  MojoWaitFlags flags = Wrapper<MojoWaitFlags>::ToNative(info[2]);
+
+  uint32_t num_bytes = buffer.num_bytes();
+  uint32_t num_handles = handles.size();
+  MojoResult result = mojo::ReadMessage(handle,
+                                        buffer.bytes(),
+                                        &num_bytes,
+                                        handles.data(),
+                                        &num_handles,
+                                        flags);
+  handles.resize(num_handles);
+
+  // TODO(abarth): We should benchmark this codepath to make sure it's ok to
+  // allocate all this memory on each read.
+
+  v8::Handle<v8::Object> object = v8::Object::New();
+  object->Set(v8::String::NewSymbol("result"),
+              Wrapper<MojoResult>::ToObject(isolate, result));
+  object->Set(v8::String::NewSymbol("bytesRead"),
+              Wrapper<uint32_t>::ToObject(isolate, num_bytes));
+  object->Set(v8::String::NewSymbol("handles"),
+              ToObjectArray(isolate, handles));
+  info.GetReturnValue().Set(object);
+}
+
+// TODO(abarth): Implement these functions. Unlike the functions above,
+//               these functions don't operate on an individual handle.
+//
+// MojoResult WaitMany(const Handle* handles,
+//                     const MojoWaitFlags* flags,
+//                     uint32_t num_handles,
+//                     MojoDeadline deadline);
+// MojoResult CreateMessagePipe(Handle* handle_0, Handle* handle_1);
+
+}
+
+v8::Local<v8::ObjectTemplate> Wrapper<mojo::Handle>::CreateTemplate() {
+  v8::Local<v8::ObjectTemplate> handle_template = v8::ObjectTemplate::New();
+  handle_template->SetInternalFieldCount(kNumberOfInternalFields);
+  handle_template->Set(v8::String::NewSymbol("close"),
+                       v8::FunctionTemplate::New(CloseCallback));
+  handle_template->Set(v8::String::NewSymbol("wait"),
+                       v8::FunctionTemplate::New(WaitCallback));
+  handle_template->Set(v8::String::NewSymbol("writeMessage"),
+                       v8::FunctionTemplate::New(WriteMessageCallback));
+  handle_template->Set(v8::String::NewSymbol("readMessage"),
+                       v8::FunctionTemplate::New(ReadMessageCallback));
+  return handle_template;
+}
+
+bool Wrapper<mojo::Handle>::HasInstance(v8::Handle<v8::Object> object) {
+  return WrapperInfo::From(object) == &g_handle_wrapper_info;
+}
+
+v8::Handle<v8::Object> Wrapper<mojo::Handle>::ToObject(
+    v8::Isolate* isolate, mojo::Handle handle) {
+  V8PerIsolateData* data = V8PerIsolateData::From(isolate);
+  v8::Local<v8::Object> object = data->handle_template()->NewInstance();
+  object->SetAlignedPointerInInternalField(
+      kWrapperInfoIndex, &g_handle_wrapper_info);
+  object->SetInternalField(
+      kEncodedValueIndex, v8::Integer::NewFromUnsigned(handle.value, isolate));
+  return object;
+}
+
+mojo::Handle Wrapper<mojo::Handle>::ToNative(
+    v8::Handle<v8::Object> object) {
+  if (!HasInstance(object))
+    return mojo::kInvalidHandle;
+  return ToNativeUnchecked(object);
+}
+
+mojo::Handle Wrapper<mojo::Handle>::ToNativeUnchecked(
+    v8::Handle<v8::Object> object) {
+  v8::Handle<v8::Value> field = object->GetInternalField(kEncodedValueIndex);
+  mojo::Handle handle = { field->Uint32Value() };
+  return handle;
+}
+
+}  // namespace js
+}  // mojo