src: refactor of CopyProperties with V8 5.5 DefineProperty #11102

AnnaMag · 2017-02-01T15:24:42Z

Checklist

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

Affected core subsystem(s)

vm: remove JavaScript code from CopyProperties()

CopyProperties() is refactored to use the V8 5.5 DefineProperty() API call.

The change maintains current behavior. This is step 1
in removing the CopyProperties() function (follow-up PR).
API improvements fix V8 SetNamedPropertyHandler
to properly treat the ES6 syntax and CopyProperties()
becomes redundant.

Strings used as property attributes and accessors
are defined as persistent strings in src/env.h.

AnnaMag · 2017-02-01T15:25:05Z

cc/ @fhinkel

mscdex · 2017-02-01T15:31:48Z

src/node_contextify.cc

+            ->GetOwnPropertyDescriptor(context, key).ToLocalChecked());
+
+        bool isAccessor = object_from_vm_context
+            ->Has(context, String::NewFromUtf8(env()->isolate(), "get"))


I don't know what the norm/rule is offhand, but perhaps we should make these persistent strings (defined in src/env.h)?

That's correct. We should create pre-allocated string in env.h else this will allocate v8::String every time we call CopyProperties.

Generally, if the string is going to be used frequently or more than once. I'm definitely + 1 on making these persistent.

changes included. Thanks!

fhinkel · 2017-02-01T15:32:11Z

Can you change to commit message so it matches our guidelines please? It should be at most 50 characters long.

kunalspathak · 2017-02-01T16:20:25Z

src/node_contextify.cc

+              ->Get(context, String::NewFromUtf8(env()->isolate(), "writable"))
+              .ToLocalChecked())->BooleanValue();
+
+          desc = new PropertyDescriptor(value, writable);


Who manages the lifetime of desc? When will get cleaned up?

It's deleted at the end of the function.

ah, didn't notice that. Thanks @fhinkel

TimothyGu · 2017-02-02T19:57:55Z

src/node_contextify.cc

-          clone_property_method = Local<Function>::Cast(script->Run());
-          CHECK(clone_property_method->IsFunction());
+        Local<Object> desc_from_vm_context = Local<Object>::Cast(global
+            ->GetOwnPropertyDescriptor(context, key).ToLocalChecked());


I think it's more common to use As<T>() than using Local<T>::Cast in the codebase, like

Local<Object> desc_from_vm_context = global->GetOwnPropertyDescriptor(context, key) .ToLocalChecked().As<Object>();

True- I didn't realize this file was the only one in src/ using Local<T>::Cast .
Good point!

TimothyGu · 2017-02-02T19:58:51Z

src/node_contextify.cc

+        if (!isAccessor) {
+          Local<Value> value = Local<Value>::Cast(desc_from_vm_context
+              ->Get(context, env()->value_string())
+              .ToLocalChecked());


Same here (Local<Value>), though in this case you don't even need to cast because Get() returns a MaybeLocal<Value>.

TimothyGu · 2017-02-02T20:01:08Z

src/node_contextify.cc

    }
  }
+}


This line seems to prevent the file from compiling.

Thanks @TimothyGu.
I have just re-compiled it and re-run the tests. All seems to be working fine.

bnoordhuis · 2017-02-03T12:57:31Z

src/node_contextify.cc

+            global->GetOwnPropertyDescriptor(context, key)
+            .ToLocalChecked().As<Object>();
+
+        bool isAccessor = desc_from_vm_context


Style: can you name this is_accessor?

bnoordhuis · 2017-02-03T17:26:34Z

src/node_contextify.cc

+            ->Has(context, env()->get_string())
+            .FromJust() || desc_from_vm_context
+                ->Has(context, env()->set_string())
+                .FromJust();


This is mostly just personal preference but it's kind of a run-on line of code that's arguably more legible when written like this:

bool is_accessor = desc_from_vm_context->Has(context, env()->get_string()) .FromJust() || desc_from_vm_context->Has(context, env()->set_string()) .FromJust();

If you shorten desc_from_vm_context you can probably even make it fit on fewer lines.

But whatever you do, the convention in core is to break after the '=' when the RHS doesn't fit on a single line. Can you update that here and below?

bnoordhuis · 2017-02-03T17:32:26Z

src/node_contextify.cc

+
+          bool writable = desc_from_vm_context
+              ->Get(context, env()->writable_string()).ToLocalChecked()
+              .As<Value>()->BooleanValue();


You don't have to cast to Value.

bnoordhuis · 2017-02-03T17:38:31Z

src/node_contextify.cc

+
+        PropertyDescriptor* desc;
+
+        if (!isAccessor) {


Minor style issue: don't negate in conditionals unless necessary. Remove the ! and swap the else/then clauses, it's easier to read.

bnoordhuis · 2017-02-03T17:41:55Z

src/node_contextify.cc

+            .As<Value>()->BooleanValue());
+        desc->set_enumerable(desc_from_vm_context
+            ->Get(context, env()->enumerable_string()).ToLocalChecked()
+            .As<Value>()->BooleanValue());


You can get rid of the desc = new PropertyDescriptor(...) and delete desc calls if you wrap this code in a lambda, like this:

auto configure = [&] (PropertyDescriptor* desc) { // ... };

Which you then call like this:

if (is_accessor) { // ... PropertyDescriptor desc(get, set); configure(&desc); } else { // ... PropertyDescriptor desc(value, writable); configure(&desc); }

I did not find a way to avoid doubling the DefineProperty call after configure(&desc):

sandbox_obj->DefineProperty(context, key, desc);

Is it ok?

AnnaMag · 2017-02-03T18:57:08Z

@bnoordhuis, updated. Thanks!

bnoordhuis

Almost there.

bnoordhuis · 2017-02-04T11:35:51Z

src/node_contextify.cc

+
+          PropertyDescriptor desc(get, set);
+          configure(&desc);
+          sandbox_obj->DefineProperty(context, key, desc);


You can move the DefineProperty call into lambda. Invoke it with sandbox_obj->DefineProperty(context, key, *desc); (note the star.)

If we call sandbox->DefineProperty() inside configure, which should probably rename the lambda. Maybe define_property_on_sandbox()?

I included the improvements and suggestions. Thanks!

bnoordhuis · 2017-02-04T11:37:00Z

src/node_contextify.cc

+                .As<Value>()->BooleanValue());
+            desc->set_enumerable(desc_vm_context
+                ->Get(context, env()->enumerable_string()).ToLocalChecked()
+                .As<Value>()->BooleanValue());


You don't need the casts to Value here, it's already a Value. Can you use the BooleanValue() overloads that take a v8::Context? (Below too.)

CopyProperties() is refactored to use the V8 5.5 DefineProperty() API call. The change does not alter current behaviour. It is a step prior to removing the function CopyProperties, which becomes reduntant after fixes of V8 SetNamedPropertyHandler in 5.5. V8. Strings used as property attributes (value, enumerable etc) and accessors are defined as persistent strings in src/env.h

bnoordhuis

LGTM. CI: https://ci.nodejs.org/job/node-test-pull-request/6217/

bnoordhuis · 2017-02-04T13:30:08Z

src/node_contextify.cc

+                ->Get(context, env()->enumerable_string()).ToLocalChecked()
+                ->BooleanValue(context).FromJust());
+            sandbox_obj->DefineProperty(context, key, *desc);
+        };


We normally indent code inside lambdas with two spaces, like regular functions. However, if the linter doesn't complain, I guess I shouldn't either.

fhinkel · 2017-02-05T09:00:37Z

Thanks! Landed in 67af1ad.

CopyProperties() is refactored to use the V8 5.5 DefineProperty() API call. The change does not alter current behaviour. It is a step prior to removing the function CopyProperties, which becomes reduntant after fixes of V8 SetNamedPropertyHandler in 5.5. V8. Strings used as property attributes (value, enumerable etc) and accessors are defined as persistent strings in src/env.h PR-URL: nodejs#11102 Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: James M Snell <jasnell@gmail.com>

italoacasas · 2017-02-05T19:45:26Z

In order to land this on v7 we need to wait for the v8 5.5 backport #11029

CopyProperties() is refactored to use the V8 5.5 DefineProperty() API call. The change does not alter current behaviour. It is a step prior to removing the function CopyProperties, which becomes reduntant after fixes of V8 SetNamedPropertyHandler in 5.5. V8. Strings used as property attributes (value, enumerable etc) and accessors are defined as persistent strings in src/env.h PR-URL: #11102 Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: James M Snell <jasnell@gmail.com>

CopyProperties() is refactored to use the V8 5.5 DefineProperty() API call. The change does not alter current behaviour. It is a step prior to removing the function CopyProperties, which becomes reduntant after fixes of V8 SetNamedPropertyHandler in 5.5. V8. Strings used as property attributes (value, enumerable etc) and accessors are defined as persistent strings in src/env.h PR-URL: nodejs#11102 Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: James M Snell <jasnell@gmail.com>

nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. vm Issues and PRs related to the vm subsystem. labels Feb 1, 2017

AnnaMag changed the title ~~refactor of CopyProperties in node_contextify.cc using V8 5.5 DefineProperty~~ src: refactor of CopyProperties in node_contextify.cc using V8 5.5 DefineProperty Feb 1, 2017

mscdex reviewed Feb 1, 2017

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targos added dont-land-on-v4.x labels Feb 1, 2017

kunalspathak reviewed Feb 1, 2017

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AnnaMag force-pushed the v8-5.5_CP branch 4 times, most recently from ba5235e to 93ae019 Compare February 2, 2017 19:21

AnnaMag changed the title ~~src: refactor of CopyProperties in node_contextify.cc using V8 5.5 DefineProperty~~ src: refactor of CopyProperties with V8 5.5 DefineProperty Feb 2, 2017

TimothyGu reviewed Feb 2, 2017

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AnnaMag force-pushed the v8-5.5_CP branch 3 times, most recently from a525064 to 128aeb2 Compare February 3, 2017 11:08

fhinkel approved these changes Feb 3, 2017

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bnoordhuis requested changes Feb 3, 2017

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AnnaMag force-pushed the v8-5.5_CP branch from 128aeb2 to 388e3c0 Compare February 3, 2017 18:21

bnoordhuis requested changes Feb 4, 2017

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AnnaMag force-pushed the v8-5.5_CP branch from 388e3c0 to ef1ad4e Compare February 4, 2017 12:08

AnnaMag force-pushed the v8-5.5_CP branch from ef1ad4e to 9cb6174 Compare February 4, 2017 12:14

bnoordhuis approved these changes Feb 4, 2017

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jasnell approved these changes Feb 4, 2017

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fhinkel closed this Feb 5, 2017

italoacasas added the dont-land-on-v7.x label Feb 5, 2017

bnoordhuis mentioned this pull request Feb 9, 2017

src: fix -Wunused-result compiler warning #11197

Merged

italoacasas removed the dont-land-on-v7.x label Feb 10, 2017

italoacasas mentioned this pull request Feb 13, 2017

Proposal - 7.6.0 (Current) #11185

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src: refactor of CopyProperties with V8 5.5 DefineProperty #11102

src: refactor of CopyProperties with V8 5.5 DefineProperty #11102

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src: refactor of CopyProperties with V8 5.5 DefineProperty #11102

src: refactor of CopyProperties with V8 5.5 DefineProperty #11102

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AnnaMag commented Feb 1, 2017 • edited Loading

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