src: lazily load internalBinding('uv') and build the errmap lazily

[joyeecheung]

This removes the internalBinding('uv') call from the normal
bootstrap for now, and avoids building errmap by default which
expands to a lot of calls into V8.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

[nodejs-github-bot]

@joyeecheung build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/2011/pipeline

[joyeecheung]

cc @addaleax

[addaleax]

Btw, I’ve also thought about creating a static array from the macro here, instead of generating the full code for each entry… that might make things a bit easier as well?

[joyeecheung]

creating a static array from the macro here

I don't think I follow..what do you mean by creating a static array?

[addaleax]

@joyeecheung This might not compile because I wrote it here in Github, but I think you get the idea:

static const struct {
  int value;
  const char* name;
  const char* message;
} errors[] = {
#define V(name, msg) { UV_##name, #name, msg }, 
  UV_ERRNO_MAP(V)
#undef V
  { 0, nullptr, nullptr }
};

for (const auto* error = errors; error->name != nullptr; error++) {
    Local<Value> arr[] = {
      OneByteString(isolate, error->name),
      OneByteString(isolate, error->msg)
    };
    if (err_map->Set(context,
                     Integer::New(isolate, error->value),
                     Array::New(isolate, arr, arraysize(arr))).IsEmpty()) {
      return;
    }
}

The major advantage would probably be that the code isn’t several kilobytes large in this case. No strong feelings about it, though :)

[joyeecheung]

Rebased and used the static struct array based the suggestion from @addaleax (thanks!), @addaleax @danbev @jasnell @BridgeAR PTAL.

CI: https://ci.nodejs.org/job/node-test-pull-request/19855/

[joyeecheung]

Landed in c66c073