APIs required to implement inspector

[bartlomieju]

• v8_inspector::V8Inspector
  • create
  • connect
  • StringView
• v8_inspector::ContextInfo
  • new
• v8_inspector::InspectorSession
  • dispatchProtocolMessage
  • schedulePauseOnNextStatement
• API to get Rust String out of StringView if it is two-byte string (!string_view.is_8_bit())

CC @piscisaureus

[piscisaureus]

• API to get Rust String out of StringView if it is two-byte string (!string_view.is_8_bit())

1. Not sure you need it at all. I think all you need to do is forward the message between the client and server.
2. If you do need it, this would do the trick: https://doc.rust-lang.org/std/string/struct.String.html#method.from_utf16.
3. Also, an 8bit string_view is not encoded as UTF8 but as Latin-1. Converting an 8bit StringView is probably more involved than converting a 16bit string.

[bartlomieju]

Not sure you need it at all. I think all you need to do is forward the message between the client and server.

I'm prototyping now on types, you might be right, I'll get back on that

If you do need it, this would do the trick: https://doc.rust-lang.org/std/string/struct.String.html#method.from_utf16.

👍

Also, an 8bit string_view is not encoded as UTF8 but as Latin-1. Converting an 8bit StringView is probably more involved than converting a 16bit string.

You are right, looks like previous implementation did convert to Utf8Value before actually encoding into string.

void InspectorFrontend::Send(const v8_inspector::StringView& string) {
  v8::HandleScope handle_scope(isolate_);
  int length = static_cast<int>(string.length());
  DCHECK_LT(length, v8::String::kMaxLength);
  Local<String> message =
      (string.is8Bit()
           ? v8::String::NewFromOneByte(
                 isolate_,
                 reinterpret_cast<const uint8_t*>(string.characters8()),
                 v8::NewStringType::kNormal, length)
           : v8::String::NewFromTwoByte(
                 isolate_,
                 reinterpret_cast<const uint16_t*>(string.characters16()),
                 v8::NewStringType::kNormal, length))
          .ToLocalChecked();

  String::Utf8Value utf8(isolate_, message);
  std::string str(*utf8);

  char* cstr = &str[0u];

  deno_->inspector_message_cb_(deno_->hack_, cstr);
}

[bartlomieju]

• API to get Rust String out of StringView if it is two-byte string (!string_view.is_8_bit())

1. Not sure you need it at all. I think all you need to do is forward the message between the client and server.
2. If you do need it, this would do the trick: https://doc.rust-lang.org/std/string/struct.String.html#method.from_utf16.
3. Also, an 8bit string_view is not encoded as UTF8 but as Latin-1. Converting an 8bit StringView is probably more involved than converting a 16bit string.

Okay, checked, we need that conversion because those messages are pushed/pulled via WS socket which requires String type for messages.

[kitsonk]

In order to solve denoland/deno#106 we would also need the following APIs exposed:

• Profiler.startPreciseCoverage
• Profiler.takePreciseCoverage
• Profiler.stopPreciseCoverage

A V8 blog post describes the process in detail.

[piscisaureus]

Closing this as the currently bound APIs were sufficient to implement the inspector in Deno.

If other APIs mentioned in this thread (e.g. Profiler.*) are still missing and still needed, feel free to open a separate issue (or PR).