src: replace ->To*(isolate) with ->To*(context).ToLocalChecked() by Leko · Pull Request #17343 · nodejs/node

Leko · 2017-11-27T07:25:56Z

This is part of Nodefest's Code and Learn nodejs/code-and-learn#72

Replace ->To*(isolate) with ->To*(context).ToLocalChecked() in src files.

Checklist

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

Affected core subsystem(s)

src

See #17244

hiroppy · 2017-11-27T07:39:02Z

/cc @joyeecheung

bnoordhuis

Thanks, LGTM. CI: https://ci.nodejs.org/job/node-test-pull-request/11746/

addaleax · 2017-11-27T15:39:57Z

src/node.cc

  e = Exception::Error(cons);

-  Local<Object> obj = e->ToObject(env->isolate());
+  Local<Object> obj = e->ToObject(env->context()).ToLocalChecked();


I think Exception::Error always returns an object, so e.As<Object>() should also work fine (and is a bit simpler/a bit more performant)

(This applies to a lot of other places in the PR too)

Thank you for your review.

I see.
I didn't know that you could do it like that!

addaleax · 2017-11-27T15:41:02Z

src/node.cc

  Local<String> exports_string = env->exports_string();
-  Local<Object> exports = module->Get(exports_string)->ToObject(env->isolate());
+  Local<Object> exports =
+      module->Get(exports_string)->ToObject(env->context()).ToLocalChecked();


If you're already here, you can feel free to also change the Get() call to take a context argument :)

Get() call to take a context argument

I didn’t understand what you said.
Do you expect this change ?

Local<Object> exports = module->Get(exports_string).As<Object>();

If you look at v8.h, you’ll see that there are two overloads of ->Get(), one that takes a context argument and one that doesn’t (and it deprecated):

node/deps/v8/include/v8.h

Lines 3166 to 3168 in cbaf59c

V8_DEPRECATE_SOON("Use maybe version", Local<Value> Get(Local<Value> key));

V8_WARN_UNUSED_RESULT MaybeLocal<Value> Get(Local<Context> context,

Local<Value> key);

At some point, we’re going to use the latter here instead of module->Get(exports_string). Whether you want to do the conversion in this PR or not is up to you :)

If you want to see an example of how these conversions look like, you can take a look at #16247.

Thank you for detailed information.

If you look at v8.h,

I will check the header file properly after this.

I update to add Local<Context> argument.
Please check my changes !

addaleax · 2017-11-27T15:45:38Z

src/node_contextify.cc


    TryCatch try_catch(env->isolate());
-    Local<String> code = args[0]->ToString(env->isolate());
+    Local<String> code = args[0]->ToString(env->context()).ToLocalChecked();


This change is actually incorrect, I think (didn't try this out yet, so I might be wrong):

new vm.Script({ toString() { throw new Error(); } });

would make ToString() return an empty MaybeLocal, right? That's fine because we have a try_catch here to check for those kinds of conditions.

So I think the two options are:

Use .FromMaybe(Local<String>()) to get the previous behaviour

Move this line to before the TryCatch and return from the function immediately if the result is empty

Either way, it would be nice if you could add a test that the code snippet above doesn't crash the process :)

would make ToString() return an empty MaybeLocal, right?

Yes it is.
I confirmed that it will crash when running that code.

./node test.js FATAL ERROR: v8::ToLocalChecked Empty MaybeLocal. 1: node::Abort() [/Users/leko/.ghq/github.com/Leko/node/./node] 2: node::FatalException(v8::Isolate*, v8::Local<v8::Value>, v8::Local<v8::Message>) [/Users/leko/.ghq/github.com/Leko/node/./node] 3: v8::V8::ToLocalEmpty() [/Users/leko/.ghq/github.com/Leko/node/./node] 4: node::(anonymous namespace)::ContextifyScript::New(v8::FunctionCallbackInfo<v8::Value> const&) [/Users/leko/.ghq/github.com/Leko/node/./node] 5: v8::internal::FunctionCallbackArguments::Call(void (*)(v8::FunctionCallbackInfo<v8::Value> const&)) [/Users/leko/.ghq/github.com/Leko/node/./node] 6: v8::internal::MaybeHandle<v8::internal::Object> v8::internal::(anonymous namespace)::HandleApiCallHelper<true>(v8::internal::Isolate*, v8::internal::Handle<v8::internal::HeapObject>, v8::internal::Handle<v8::internal::HeapObject>, v8::internal::Handle<v8::internal::FunctionTemplateInfo>, v8::internal::Handle<v8::internal::Object>, v8::internal::BuiltinArguments) [/Users/leko/.ghq/github.com/Leko/node/./node] 7: v8::internal::Builtin_Impl_HandleApiCall(v8::internal::BuiltinArguments, v8::internal::Isolate*) [/Users/leko/.ghq/github.com/Leko/node/./node] 8: 0x32b64f842fd Abort trap: 6

So I added test case and fix it.
Please check it again.

addaleax · 2017-11-27T15:46:09Z

src/node_file.cc

  char * buf = nullptr;

-  Local<Object> buffer_obj = args[1]->ToObject(env->isolate());
+  Local<Object> buffer_obj = args[1]->ToObject(env->context()).ToLocalChecked();


I think this can be .As<Object>() as well since we already checked that it's a buffer

You mean I should update as follow:

Local<Object> buffer_obj = args[1]->ToObject(env->context()).ToLocalChecked();

to

Local<Object> buffer_obj = args[1].As<Object>();

It is OK ?
I changed as described above, the test passed.

Yes, exactly. If you know that something is an Object instance, I would recommend using .As<Object>(), because that boils down to a simple pointer cast (i.e. has zero runtime cost), unlike ToObject() which always calls into the JS engine.

Thank you for confirmation.

because that boils down to a simple pointer cast (i.e. has zero runtime cost), unlike ToObject() which always calls into the JS engine.

I didn't know that ! Thanks for letting me know.

> Exception::Error always returns an object, so e.As<Object>() should also work fine See #17343 (comment)

we already checked that its a buffer

…cript It failed with `FATAL ERROR: v8::ToLocalChecked Empty MaybeLocal`.

It fixed this test case: 19a1b2e

Dont pass Local<Context> is deprecated soon. So we migrate to maybe version.

joyeecheung · 2017-11-29T06:36:38Z

src/node.cc

  Local<String> exports_string = env->exports_string();
-  Local<Object> exports = module->Get(exports_string)->ToObject(env->isolate());
+  Local<Object> exports =
+      module->Get(env->context(), exports_string).ToLocalChecked().As<Object>();


I think here we don't know if module.exports is an object yet? The Local<Value> returned by .ToLocalChecked() should go through ->ToObject(context).ToLocalChecked() again.

@joyeecheung Thank you for review.

You mean this changes (A)

Local<Object> exports = module->Get(env->context(), exports_string).ToLocalChecked() ->ToObject(env->context()).ToLocalChecked();

or this(B) ?

Local<Object> exports = module->Get(exports_string)->ToObject(env->context()).ToLocalChecked();

I think A is better because Local<Value> Get(Local<Value> key) will be deprecated.

@Leko (A) seems better, but I think this is a situation similar to the vm one: You can actually get this to crash with the current code, and .ToLocalChecked() is not going to change that:

// The path here is just an example, any addon will work process.dlopen({ exports: undefined }, './test/addons/hello-world/build/Release/binding.node');

because calling ToObject() on undefined gives an exception and therefore an empty exports variable.

I think we want to do a similar thing to what we're doing in the vm module: If Get() or ToObject() return an empty MaybeLocal, we should call dlib.Close() to clean up the library and return from the function as soon as possible.

Thank you @addaleax .
I fixed it by d7cc341 .

Is my understanding correct ?

@l2dy yes, this seems about right! Thank you!

Not at all !
Thanks for your quick reply.

…cked

addaleax · 2017-11-30T13:07:41Z

CI: https://ci.nodejs.org/job/node-test-commit/14480/

Leko · 2017-12-01T14:40:40Z

Hi @addaleax, CI seems to be failing.
Is the cause my mistake or flaky test ?
Please trigger build again if you'd like.

joyeecheung · 2017-12-01T15:56:22Z

New arm-fanned CI: https://ci.nodejs.org/job/node-test-commit-arm-fanned/13075/

addaleax · 2017-12-01T19:53:05Z

Looks like everything’s green!

Landed in e9e9863...2355c84

Thanks for the awesome PR – please feel invited to do more of this! ✨ 🎉

Squashed from multiple commits: - src: replace ->To*(isolate) with ->To*(context).ToLocalChecked() - test: use .As<Object> on Exception::Error > Exception::Error always returns an object, so e.As<Object>() should also work fine See #17343 (comment) - test: use .As<Object> instead of ->ToObject we already checked that its a buffer - src: use FromMaybe instead of ToLocalChecked It fixed this test case: 19a1b2e - src: pass context to Get() Dont pass Local<Context> is deprecated soon. So we migrate to maybe version. - src: return if Get or ToObject return an empty before call ToLocalChecked Refs: #17244 PR-URL: #17343 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

It failed with `FATAL ERROR: v8::ToLocalChecked Empty MaybeLocal`. PR-URL: #17343 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

PR-URL: #17343 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

Squashed from multiple commits: - src: replace ->To*(isolate) with ->To*(context).ToLocalChecked() - test: use .As<Object> on Exception::Error > Exception::Error always returns an object, so e.As<Object>() should also work fine See #17343 (comment) - test: use .As<Object> instead of ->ToObject we already checked that its a buffer - src: use FromMaybe instead of ToLocalChecked It fixed this test case: 19a1b2e - src: pass context to Get() Dont pass Local<Context> is deprecated soon. So we migrate to maybe version. - src: return if Get or ToObject return an empty before call ToLocalChecked Refs: #17244 PR-URL: #17343 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

It failed with `FATAL ERROR: v8::ToLocalChecked Empty MaybeLocal`. PR-URL: #17343 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

PR-URL: #17343 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

Squashed from multiple commits: - src: replace ->To*(isolate) with ->To*(context).ToLocalChecked() - test: use .As<Object> on Exception::Error > Exception::Error always returns an object, so e.As<Object>() should also work fine See #17343 (comment) - test: use .As<Object> instead of ->ToObject we already checked that its a buffer - src: use FromMaybe instead of ToLocalChecked It fixed this test case: 19a1b2e - src: pass context to Get() Dont pass Local<Context> is deprecated soon. So we migrate to maybe version. - src: return if Get or ToObject return an empty before call ToLocalChecked Refs: #17244 PR-URL: #17343 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

It failed with `FATAL ERROR: v8::ToLocalChecked Empty MaybeLocal`. PR-URL: #17343 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

PR-URL: #17343 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

gibfahn · 2017-12-19T23:28:16Z

@addaleax Should this be backported to v8.x-staging and v6.x-staging? If yes please follow the guide and raise a backport PR, if no let me know or add the dont-land-on label.

MylesBorins · 2018-05-22T15:54:20Z

Another backport ping

src: replace ->To*(isolate) with ->To*(context).ToLocalChecked()

e41c511

See #17244

nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. lib / src Issues and PRs related to general changes in the lib or src directory. labels Nov 27, 2017

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hiroppy added the code-and-learn Issues related to the Code-and-Learn events and PRs submitted during the events. label Nov 27, 2017

addaleax reviewed Nov 27, 2017

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Leko added 4 commits November 28, 2017 21:17

test: use .As<Object> on Exception::Error

f9107cc

> Exception::Error always returns an object, so e.As<Object>() should also work fine See #17343 (comment)

test: use .As<Object> instead of ->ToObject

60f4711

we already checked that its a buffer

test: add test case that crashes when throwing an exception with vm.S…

19a1b2e

…cript It failed with `FATAL ERROR: v8::ToLocalChecked Empty MaybeLocal`.

src: use FromMaybe instead of ToLocalChecked

1926bcf

It fixed this test case: 19a1b2e

addaleax approved these changes Nov 28, 2017

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src: pass context to Get()

096cbbf

Dont pass Local<Context> is deprecated soon. So we migrate to maybe version.

joyeecheung reviewed Nov 29, 2017

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Leko added 2 commits November 30, 2017 21:27

test: add test case that crashes when process.dlopen with undefined

dbee7b0

src: return if Get or ToObject return an empty before call ToLocalChe…

d7cc341

…cked

addaleax added the author ready PRs that have at least one approval, no pending requests for changes, and a CI started. label Nov 30, 2017

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addaleax removed the author ready PRs that have at least one approval, no pending requests for changes, and a CI started. label Dec 1, 2017

addaleax closed this Dec 1, 2017

Leko deleted the replace_to_isolate_with_to_context branch December 2, 2017 07:50

MylesBorins mentioned this pull request Dec 12, 2017

v9.3.0 proposal #17631

Merged

gibfahn added lts-watch-v6.x labels Dec 19, 2017

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MylesBorins added backport-requested-v8.x and removed lts-watch-v6.x labels May 23, 2018

	V8_DEPRECATE_SOON("Use maybe version", Local<Value> Get(Local<Value> key));
	V8_WARN_UNUSED_RESULT MaybeLocal<Value> Get(Local<Context> context,
	Local<Value> key);

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Leko commented Nov 27, 2017

Checklist

Affected core subsystem(s)

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hiroppy commented Nov 27, 2017

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Leko Nov 29, 2017 •

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