n-api: make per-Context-ness of napi_env explicit #23689

addaleax · 2018-10-16T10:29:08Z

Because instances of napi_env are created on a per-global-object
basis and because most N-API functions refer to builtin JS
objects, napi_env is essentially in 1:1 correspondence with
v8::Context.

This was not clear from the implementation by itself, but has
emerged from conversations with the N-API team.

This patch changes the napi_env implementation to:

Actually store the v8::Context it represents.
Provide more direct access to the node::Environment
to which the Context belongs.
Do not store the uv_loop_t* explicitly, since it can be
inferred from the node::Environment and we actually
have an N-API method for that.
Replace calls to isolate->GetCurrentContext() with
the more appropriate napi_env Context.
Implement a better (although not perfect) way of cleaning
up napi_env instances.

Checklist

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

nodejs-github-bot · 2018-10-16T10:29:09Z

@addaleax build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/1260/pipeline

addaleax · 2018-10-16T10:29:43Z

CI: https://ci.nodejs.org/job/node-test-pull-request/17894/
Resume: https://ci.nodejs.org/job/node-test-pull-request/17903/

/cc @nodejs/n-api

mhdawson

LGTM

addaleax · 2018-10-19T17:03:50Z

Resume CI again: https://ci.nodejs.org/job/node-test-pull-request/17991/ (:heavy_check_mark:)

refack · 2018-10-20T18:56:43Z

Implement a better (although not perfect) way of cleaning
up napi_env instances.

Any reason not to simply use a shared_ptr in?

node/src/node_api.cc

Line 1156 in b3ae915

napi_env env;

src/node_api.cc

refack · 2018-10-20T19:21:42Z

src/node_api.cc

@@ -935,18 +957,21 @@ class ThreadSafeFunction : public node::AsyncResource {
  // These methods must only be called from the loop thread.

  napi_status Init() {
+    uv_loop_t* loop = nullptr;


If this is going to crash on any error, why not break the abstraction and directly call env->node_env()->event_loop();
(I'd go as far as const uv_loop_t& loop = *(env->node_env()->event_loop());, but I know I'm pushing it :)

If this is going to crash on any error, why not break the abstraction and directly call env->node_env()->event_loop();

It’s not going to crash, which is why there’s a CHECK :) But since we have an N-API function for exactly this purpose, I think it makes sense to use it here.

(I'd go as far as const uv_loop_t& loop = *(env->node_env()->event_loop());, but I know I'm pushing it :)

We can’t use a const uv_loop_t& :)

Because instances of `napi_env` are created on a per-global-object basis and because since most N-API functions refer to builtin JS objects, `napi_env` is essentially in 1:1 correspondence with `v8::Context`. This was not clear from the implementation by itself, but has emerged from conversations with the N-API team. This patch changes the `napi_env` implementation to: - Actually store the `v8::Context` it represents. - Provide more direct access to the `node::Environment` to which the `Context` belongs. - Do not store the `uv_loop_t*` explicitly, since it can be inferred from the `node::Environment` and we actually have an N-API method for that. - Replace calls to `isolate->GetCurrentContext()` with the more appropriate `napi_env` `Context`. - Implement a better (although not perfect) way of cleaning up `napi_env` instances.

mmarchini · 2018-10-24T14:13:05Z

CI: https://ci.nodejs.org/job/node-test-pull-request/18115/

addaleax · 2018-10-24T17:59:54Z

Landed in 449c0ca

Because instances of `napi_env` are created on a per-global-object basis and because since most N-API functions refer to builtin JS objects, `napi_env` is essentially in 1:1 correspondence with `v8::Context`. This was not clear from the implementation by itself, but has emerged from conversations with the N-API team. This patch changes the `napi_env` implementation to: - Actually store the `v8::Context` it represents. - Provide more direct access to the `node::Environment` to which the `Context` belongs. - Do not store the `uv_loop_t*` explicitly, since it can be inferred from the `node::Environment` and we actually have an N-API method for that. - Replace calls to `isolate->GetCurrentContext()` with the more appropriate `napi_env` `Context`. - Implement a better (although not perfect) way of cleaning up `napi_env` instances. PR-URL: #23689 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Gus Caplan <me@gus.host> Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

MylesBorins · 2018-11-26T22:15:56Z

This lands cleanly on 10.x, but there is a backlog of unlanded n-api related commits on 8.x that require a manual backport... likely part of a larger backporting effort.

Because instances of `napi_env` are created on a per-global-object basis and because since most N-API functions refer to builtin JS objects, `napi_env` is essentially in 1:1 correspondence with `v8::Context`. This was not clear from the implementation by itself, but has emerged from conversations with the N-API team. This patch changes the `napi_env` implementation to: - Actually store the `v8::Context` it represents. - Provide more direct access to the `node::Environment` to which the `Context` belongs. - Do not store the `uv_loop_t*` explicitly, since it can be inferred from the `node::Environment` and we actually have an N-API method for that. - Replace calls to `isolate->GetCurrentContext()` with the more appropriate `napi_env` `Context`. - Implement a better (although not perfect) way of cleaning up `napi_env` instances. PR-URL: #23689 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Gus Caplan <me@gus.host> Reviewed-By: Matheus Marchini <mat@mmarchini.me> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. node-api Issues and PRs related to the Node-API. labels Oct 16, 2018

jasnell approved these changes Oct 16, 2018

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mhdawson approved these changes Oct 16, 2018

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addaleax added the author ready PRs that have at least one approval, no pending requests for changes, and a CI started. label Oct 20, 2018

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addaleax added 2 commits October 21, 2018 03:59

fixup! n-api: make per-Context-ness of napi_env explicit

2f3c078

addaleax force-pushed the napi-context branch from 9024ab2 to 2f3c078 Compare October 21, 2018 02:02

addaleax closed this Oct 24, 2018

addaleax deleted the napi-context branch October 24, 2018 18:00

targos mentioned this pull request Oct 27, 2018

Release proposal: v11.1.0 #23922

Merged

MylesBorins added the backport-requested-v8.x label Nov 26, 2018

MylesBorins added the land-on-v10.x label Nov 26, 2018

codebytere mentioned this pull request Nov 27, 2018

v10.13.1 proposal #24675

Closed

codebytere mentioned this pull request Nov 29, 2018

v10.14.2 proposal #24727

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n-api: make per-Context-ness of napi_env explicit #23689

n-api: make per-Context-ness of napi_env explicit #23689

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n-api: make per-Context-ness of napi_env explicit #23689

n-api: make per-Context-ness of napi_env explicit #23689

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