Implement Node-API in bun.js (napi)

Question

Implement Node-API in bun.js (napi)

Jarred-Sumner opened this issue 2 years ago · 44 comments

Answer 1 · 2022-05-14T03:11:39.000Z

I made a test repo that exercises a number of things that are currently having problems with the bun napi interface:
https://github.com/kriszyp/bun-test-apw
Clone that, npm install it, and then you can compare node index.js to bun index.js:

Occasional segfaults in calls through napi_call_threadsafe_function
napi_release_threadsafe_function not triggering thread_finalize_cb
NAPI_MODULE macro fails with symbol 'napi_register_module_v1' not found in native module (easy workaround, since NAPI_MODULE_INIT works fine)
If you get through those, I think the Callback().Call() ends up triggering escapable scopes, but that's not that important.

You will have uncomment NAPI_MODULE from apw.cpp (and comment NODE_MODULE_INIT) when you want to test that, figured the other things were more important.

Hope that helps, thanks for the great work!

Answer 2 · 2022-05-15T12:48:27.000Z

I also wanted to check to see if this is roughly the right approach loading a module for napi + ffi usage. I think the hybrid strategy is good: use napi for general purpose stuff like building objects, async work, and use ffi for "hot" functions that need to be fast. Here is an example from my code where I am loading the platform's binary with the napi loading package, and then, if running in bun, loading it through the FFI loader. But, I think this raises a couple points:

I assume calling dlopen twice (once through the napi loader, once through the ffi loader) is cached at some level of the OS and doesn't result in duplicate binary footprints in memory
require.resolve doesn't seem to exist in bun, and this seems challenging for loading a platform-specific package with a binary, which is direction that we are going with node-gyp-build: https://github.com/prebuild/node-gyp-build/pull/45/files#diff-e727e4bdf3657fd1d798edcd6b099d6e092f8573cba266154583a746bba0f346R50

Anyway, here is my loading sequence right now:

import { dirname, join, default as pathModule } from 'path';
import { fileURLToPath } from 'url';
import loadNAPI from 'node-gyp-build'; // loads the correct napi binary, using the current OS/arch

let dirName = (typeof __dirname == 'string' ? __dirname : // for bun, which doesn't have fileURLToPath
	dirname(fileURLToPath(import.meta.url))).replace(/dist$/, ''); // for node, which doesn't have __dirname in ESM

export let nativeAddon = loadNAPI(dirName);
if (process.isBun) {
	const { dlopen, FFIType } = require('bun:ffi');
	// load the same napi module as above, but use bun's ffi
	// ideally we should use require.resolve to find a package, but here just hoping it is a sibling package in node_modules
	let libPath = join(dirName, '..', 'lmdb-linux-' + process.arch, 'node.napi.node');
	let lmdbLib = dlopen(libPath, {
		getByBinary: { args: [FFIType.f64, FFIType.u32], returns: FFIType.u32},
		iterate: { args: [FFIType.f64], returns: FFIType.i32},
		position: { args: [FFIType.f64, FFIType.u32, FFIType.u32, FFIType.u32, FFIType.f64], returns: FFIType.i32},
		write: { args: [FFIType.f64, FFIType.f64], returns: FFIType.i32},
		resetTxn: { args: [FFIType.f64], returns: FFIType.u8},
	});
	Object.assign(nativeAddon, lmdbLib.symbols);
}

Answer 3 · 2022-05-15T12:58:08.000Z

let dirName = (typeof __dirname == 'string' ? __dirname : // for bun, which doesn't have fileURLToPath

For bun you can also do import.meta.dir and/or import.meta.path, which at least saves you from the typeof check

I assume calling dlopen twice (once through the napi loader, once through the ffi loader) is cached at some level of the OS and doesn't result in duplicate binary footprints in memory

This is a good point. I don't know either, but worth checking.

require.resolve doesn't seem to exist in bun, and this seems challenging for loading a platform-specific package with a binary, which is direction that we are going with node-gyp-build: https://github.com/prebuild/node-gyp-build/pull/45/files#diff-e727e4bdf3657fd1d798edcd6b099d6e092f8573cba266154583a746bba0f346R50

This is an oversight – require.resolve should exist but does not currently. There are at least 5 other ways you can resolve without loading modules though:

Bun.resolve(path, fromPath) (async)
Bun.resolveSync(path, fromPath)
import.meta.resolve(path) (async)
import.meta.resolveSync(path) (sync)
Loader.resolveSync (lower-level, uses JSC builtin ModuleLoader and may be disabled at some point)

Answer 4 · 2022-05-15T13:10:47.000Z

assume calling dlopen twice (once through the napi loader

My evidence is that when I set the value of a static C variable from a NAPI call, that value was accessible/correct from an FFI call, so I think working correctly, but I am not claiming this as absolute proof.

This is an oversight – require.resolve should exist but does not currently

Ok, so you plan on adding require.resolve? I think in node-gyp-build it would either need to go through createRequire(libraryPath), or use the two arg version (require.resolve(id, { path: [ libraryPath ] }). node-gyp-build is CJS module, so unfortunately import.meta.resolve can't be used there (and can't even be mentioned, if (false) import.meta.resolve('test') will even fail in Node in CJS mode).

Anyway, thanks for the progress here, I know these are probably annoying details of the napi/node machinery, but I think node-gyp-build is pretty commonly used.

Answer 5 · 2022-05-17T09:17:03.000Z

Ok, so you plan on adding require.resolve? I think in node-gyp-build it would either need to go through createRequire(libraryPath), or use the two arg version (require.resolve(id, { path: [ libraryPath ] }). node-gyp-build is CJS module, so unfortunately import.meta.resolve can't be used there (and can't even be mentioned, if (false) import.meta.resolve('test') will even fail in Node in CJS mode).

Support for both of these was added in Bun v0.0.83 (released today)

Answer 6 · 2022-07-06T02:48:49.000Z

FYI, I tried to run parcel-css with Bun, but got the following error (logging with DYLD_PRINT_APIS). Not sure if this is useful. I tried to debug with lldb but wasn't able to due to macOS code signing. I guess I'd have to compile bun myself to debug further.

dyld[50777]: dlopen("/Users/devongovett/dev/parcel-css/parcel-css.darwin-arm64.node", 0x00000001)
dyld[50777]:       dlopen(parcel-css.darwin-arm64.node) => 0x2089957e0
dyld[50777]: dlsym(0x2089957e0, "napi_register_module_v1")
dyld[50777]:      dlsym("napi_register_module_v1") => 0x110ab41b0
dyld[50777]: dlsym(0xfffffffffffffffe, "getentropy")
dyld[50777]:      dlsym("getentropy") => 0x183fd8f5c

Example:

const parcelCss  = require('./parcel-css.darwin-arm64.node');
parcelCss.transform({
  filename: 'test.css',
  code: Buffer.from('.foo { color: red }'),
  minify: true
});

Answer 7 · 2022-07-07T19:56:04.000Z

If I attempt to load a native module that uses Node-API, I get a crash on missing symbols. Additionally, I don't see any of the Node-API symbols in the bun binary (0.1.1, macOS x86_64).

Is there something additional that needs to be done to load these symbols or was this possibly optimized out in the latest release?

$ symbols $(which bun) | grep napi

Edit: It appears to be only the macOS release where they are missing. The symbols are present in linux.

Answer 8 · 2022-07-10T17:13:47.000Z

What do you mean by async_hooks resource tracking will not be supported, it will just ignore them.

As bluebird uses async_hooks and requires it explicitly like this for example:

var AsyncResource = util.isNode && util.nodeSupportsAsyncResource ?
    require("async_hooks").AsyncResource : null;

Which then results into:

Could not resolve: "async_hooks". Maybe you need to "bun install"?

Answer 9 · 2022-07-10T17:19:57.000Z

async_hooks will need to be polyfilled but initially just disabled so it is a no-op rather than failure on require() Also in bun at least, you should try to avoid Bluebird. It’s a many X slowdown

…

On Sun, Jul 10, 2022 at 10:13 AM Laurens Lavaert ***@***.***> wrote: What do you mean by async_hooks resource tracking will not be supported, it will just ignore them. As bluebird uses async_hooks and requires it explicitly like this for example: var AsyncResource = util.isNode && util.nodeSupportsAsyncResource ? require("async_hooks").AsyncResource : null; Which then results into: Could not resolve: "async_hooks". Maybe you need to "bun install"? — Reply to this email directly, view it on GitHub <#158 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAFNGSZC646YQEGC6NGCNRTVTMAFNANCNFSM5VDV6N3Q> . You are receiving this because you authored the thread.Message ID: ***@***.***>

Answer 10 · 2022-07-24T13:35:27.000Z

Also in bun at least, you should try to avoid Bluebird. It’s a many X slowdown

What would you say is recommended to use (instead)? Par example,

(async () => { for (let i=0; i<800000; i++) { await functionCall(i); } })();

...would work, but only one execution at a time.
(And without limitation program will produce errors.)
(Promise.map([...Array(800000).keys()], functionCall, {concurrency: 8});)

P. S. http://bluebirdjs.com/docs/benchmarks.html claims to be faster (in node) than async-await.
P. S. If I am not mistaken, another problem rises with big arrays: bun took 7 GB (and counting) of RAM for 800 000 keys. Speaking of slowdowns.

Answer 11 · 2022-07-27T03:49:22.000Z

PrismaJS also requires async_hook

Answer 12 · 2022-08-17T06:22:40.000Z

Hey folks! Is there any progress on napi_create_external?

Answer 13 · 2022-11-10T23:12:12.000Z

Hey folks! Is there any progress on napi_create_external?

Added in dddbce8

Answer 14 · 2023-01-23T22:43:37.000Z

When running @parcel/watcher, even just trying to import it with import watcher from '@parcel/watcher' bun fails with Segmentation fault: 11 (that's all it outputs). Since that module is written in C++ I figured it might be NAPI-related, might be related to this issue?

Answer 15 · 2023-01-23T23:11:29.000Z

When running @parcel/watcher, even just trying to import it with import watcher from '@parcel/watcher' bun fails with Segmentation fault: 11 (that's all it outputs). Since that module is written in C++ I figured it might be NAPI-related, might be related to this issue?

Yes, there are at least three issues blocking @parcel/watcher from working, of which I just fixed two:

napi_create_symbol wasn't handling a missing description string - aa45680
napi_define_property didn't support symbol properties - 4570ff7
napi_type_tag_object is not implemented yet

Implement Node-API in bun.js (napi)

Internal changes

API implementation

Test coverage