JS API: initial implementation (N-API version)

[joyeecheung]

Refs: #14

This is a revamp of #147 : now that we have dropped support of Node.js v4.x, we can use N-API (or the C++ wrapper to be exact) to build the binding (which is much easier to use than the V8 API/NAN). It builds on previous work that refactored the build files and restructured how llnode instances are created so this PR is much smaller than what #147 originally was.

The current API is laid down in JSAPI.md, currently the results of the inspection are just strings that we use to print in LLDB instead of structured data - we can implement custom inspector of different types in llv8.h later so that proper JS objects can be returned back to JS.

Note that the current test does not pass on Node v10 core dumps since object inspection of llnode is half-broken on Node v10 (e.g. process.platform is recognized as Smi)

cc @mmarchini @bnoordhuis

[mmarchini]

Note that the current test does not pass on Node v10 core dumps since object inspection of llnode is half-broken on Node v10 (e.g. process.platform is recognized as Smi)

Do we have an issue to fix this?

[joyeecheung]

@mmarchini I don't think so, in general llnode seems pretty broken on v10. Here is what the process object looks like in v10.5.0

See `v8 inspect` output

0x00002974b3103e51:<Object: process properties {
    .title=<unknown field type>,
    .version=<Smi: 1>,
    .versions=<Smi: 1>,
    .arch=<Smi: 1>,
    .platform=<Smi: 1>,
    .release=<Smi: 1>,
    .argv=0x000029740ad2a5e9:<Array: length=2>,
    .execArgv=0x000029740ad2a609:<Array: length=1>,
    .env=0x000029740ad2a629:<Object: (anonymous)>,
    .pid=<Smi: 1>,
    .features=<Smi: 1>,
    .ppid=<unknown field type>,
    .execPath=0x000029740ad2a679:<String: "/Users/joyee/.nv...">,
    .debugPort=<unknown field type>,
    ._startProfilerIdleNotifier=<unknown field type>,
    ._stopProfilerIdleNotifier=<unknown field type>,
    .abort=<unknown field type>,
    .chdir=0x0000297451b5b269:<function: chdir at (external).js:20:33>,
    .umask=0x0000297451b5b2a9:<function: umask at (external).js:24:33>,
    ._getActiveRequests=<unknown field type>,
    ._getActiveHandles=<unknown field type>,
    .reallyExit=<unknown field type>,
    .cwd=<unknown field type>,
    .getuid=<unknown field type>,
    .geteuid=<unknown field type>,
    .getgid=<unknown field type>,
    .getegid=<unknown field type>,
    .getgroups=<unknown field type>,
    ._kill=<unknown field type>,
    .dlopen=<unknown field type>,
    ._debugProcess=<unknown field type>,
    ._debugEnd=<unknown field type>,
    .hrtime=0x0000297451b5c929:<function: hrtime at (external).js:96:35>,
    .cpuUsage=0x0000297451b5cc81:<function: cpuUsage at (external).js:35:39>,
    .uptime=<unknown field type>,
    .memoryUsage=0x0000297451b5cf31:<function: memoryUsage at (external).js:123:45>,
    ._rawDebug=0x0000297451b60759:<function: process._rawDebug at (external).js:250:31>,
    .moduleLoadList=<Smi: 1>,
    .binding=<unknown field type>,
    ._linkedBinding=<unknown field type>,
    ._events=0x000029740ad2a6c1:<Object: Object>,
    ._eventsCount=<Smi: 4>,
    ._maxListeners=0x0000297467d022e1:<undefined>,
    ._fatalException=<unknown field type>,
    .domain=0x0000297467d02201:<null>,
    ._exiting=0x0000297467d023f1:<false>,
    .assert=<unknown field type>,
    .config=0x0000297474f99471:<Object: Object>,
    .setUncaughtExceptionCaptureCallback=<unknown field type>,
    .hasUncaughtExceptionCaptureCallback=<unknown field type>,
    .emitWarning=<unknown field type>,
    .nextTick=<unknown field type>,
    ._tickCallback=<unknown field type>,
    .stdout=<unknown field type>,
    .stderr=<unknown field type>,
    .stdin=<unknown field type>,
    .openStdin=<unknown field type>,
    .initgroups=<unknown field type>,
    .setegid=<unknown field type>,
    .seteuid=<unknown field type>,
    .setgid=<unknown field type>,
    .setuid=<unknown field type>,
    .setgroups=<unknown field type>,
    .exit=<unknown field type>,
    .kill=<unknown field type>,
    .argv0=0x000029740ad30a11:<String: "node">,
    .mainModule=0x000029746a782ae1:<Object: Module>}>

I updated this PR to fix the compilation error on Windows now that #203 landed. I've split that commit into #208

[joyeecheung]

So, a few things to do before this can land:

1. Skip the addon build and the test for nightly and canary since node-addon-api isn't there yet
2. Node.js 6.x does not have objects with the classTickObject and console
3. Node.js 10.x is broken. We can either skip the test that looks into the process object, or keep it.

[mmarchini]

Node.js 10.x is broken. We can either skip the test that looks into the process object, or keep it.

IMO we should keep it since we'll have to fix v10.x sooner or later.

[mmarchini]

Here is what the process object looks like in v10.5.0

Ahh, something changed between v10.4.0 and v10.5.0. 10.4.0 seems to be working fine (at least for the process object).

[joyeecheung]

@mmarchini I've updated the build files and the tests:

• Split tests to test/addon and test/plugin
• Skip building addons and running addon tests in nightly and
  canary builds in Travis
• Do not build the addon by default (so normal users who npm install the release from npm registry will not be affected) for now
• Add instructions about building and testing the addon in the README (only in the "Develop & Test" section though, we might want to clean up the docs later)
• Do not expect console and TickObject in the heap since they are not there in 6.x

There are only two failures in Travis now:

• canary is broken (because llnode is broken on V8 TOT)
• 10.x is broken on mac OX (because llnode is broken there process object with weird attributes in Node.js v10.5.0 #209)

This should be safe to land now.

[joyeecheung]

@mmarchini Does this still look good to you?

[mmarchini]

Yes! :)