vm: make ContextifyContext a BaseObject #44796

joyeecheung · 2022-09-26T14:28:35Z

src: refactor BaseObject methods

Wrap the initialization of the kSlot and kEmbedderType fields
into a BaseObject::SetInternalFields() method.
Move the tagging of kEmbedderType field into
BaseObject::TagNodeObject()
Add a variant of BaseObject::MakeLazilyInitializedJSTemplate()
that only needs IsolateData.
This makes it easier to create BaseObject subclasses.

benchmark: add vm context global proxy benchmark

vm: make ContextifyContext a BaseObject

Instead of adding a reference to the ContextifyContext by using
a v8::External, we make ContextifyContext a weak BaseObject that
whose wrapper is referenced by the sandbox via a private symbol.
This makes it easier to snapshot the contexts, in addition to
reusing the BaseObject lifetime management for ContextifyContexts.

joyeecheung · 2022-09-26T14:35:47Z

src/node_contextify.cc

  Local<Context> context;
-  if (!args.This()->GetCreationContext().ToLocal(&context)) {
+  if (!object->GetCreationContext().ToLocal(&context)) {


I tried using a private symbol from the receiver to the wrapper and then unwrap to get to the ContextifyContext*, which is a bit slower than the current approach, so we are still using the context embedder field here. In any case, as long as the context is alive, the sandbox must be alive (through the kSandboxObject internal field), then the wrapper must be alive (through the contextify_context_private_symbol), so the ContextifyContext is also alive. On the other hand as long as the ContextifyContext is alive, the wrapper is alive, then the context must also be alive (through the constructor).

src/node_contextify.h

- Wrap the initialization of the kSlot and kEmbedderType fields into a BaseObject::SetInternalFields() method. - Move the tagging of kEmbedderType field into BaseObject::TagNodeObject() - Add a variant of BaseObject::MakeLazilyInitializedJSTemplate() that only needs IsolateData. This makes it easier to create BaseObject subclasses.

Instead of adding a reference to the ContextifyContext by using a v8::External, we make ContextifyContext a weak BaseObject that whose wrapper is referenced by the sandbox via a private symbol. This makes it easier to snapshot the contexts, in addition to reusing the BaseObject lifetime management for ContextifyContexts.

This reverts commit b9042c87b60184a37d9c8674ec8c8b29b2a8ab5e.

nodejs-github-bot · 2022-09-28T12:01:17Z

CI: https://ci.nodejs.org/job/node-test-pull-request/46889/

legendecas · 2022-09-29T07:42:11Z

Linter is complaining.

nodejs-github-bot · 2022-09-29T08:47:53Z

CI: https://ci.nodejs.org/job/node-test-pull-request/46927/

nodejs-github-bot · 2022-09-29T12:18:37Z

CI: https://ci.nodejs.org/job/node-test-pull-request/46933/

nodejs-github-bot · 2022-10-03T10:17:15Z

CI: https://ci.nodejs.org/job/node-test-pull-request/47022/

- Wrap the initialization of the kSlot and kEmbedderType fields into a BaseObject::SetInternalFields() method. - Move the tagging of kEmbedderType field into BaseObject::TagNodeObject() - Add a variant of BaseObject::MakeLazilyInitializedJSTemplate() that only needs IsolateData. This makes it easier to create BaseObject subclasses. PR-URL: #44796 Reviewed-By: Chengzhong Wu <[email protected]> Reviewed-By: James M Snell <[email protected]>

PR-URL: #44796 Reviewed-By: Chengzhong Wu <[email protected]> Reviewed-By: James M Snell <[email protected]>

Instead of adding a reference to the ContextifyContext by using a v8::External, we make ContextifyContext a weak BaseObject that whose wrapper is referenced by the sandbox via a private symbol. This makes it easier to snapshot the contexts, in addition to reusing the BaseObject lifetime management for ContextifyContexts. PR-URL: #44796 Reviewed-By: Chengzhong Wu <[email protected]> Reviewed-By: James M Snell <[email protected]>

joyeecheung · 2022-10-04T12:26:14Z

Landed in 00e5617...5b1bcf8

danielleadams · 2022-10-10T13:06:03Z

Hi @joyeecheung, can you open up a backport PR for this to v18.x-staging? Thank you.

PR-URL: #44796 Reviewed-By: Chengzhong Wu <[email protected]> Reviewed-By: James M Snell <[email protected]>

- Wrap the initialization of the kSlot and kEmbedderType fields into a BaseObject::SetInternalFields() method. - Move the tagging of kEmbedderType field into BaseObject::TagNodeObject() - Add a variant of BaseObject::MakeLazilyInitializedJSTemplate() that only needs IsolateData. This makes it easier to create BaseObject subclasses. PR-URL: nodejs#44796 Reviewed-By: Chengzhong Wu <[email protected]> Reviewed-By: James M Snell <[email protected]>

PR-URL: nodejs#44796 Reviewed-By: Chengzhong Wu <[email protected]> Reviewed-By: James M Snell <[email protected]>

Instead of adding a reference to the ContextifyContext by using a v8::External, we make ContextifyContext a weak BaseObject that whose wrapper is referenced by the sandbox via a private symbol. This makes it easier to snapshot the contexts, in addition to reusing the BaseObject lifetime management for ContextifyContexts. PR-URL: nodejs#44796 Reviewed-By: Chengzhong Wu <[email protected]> Reviewed-By: James M Snell <[email protected]>

`contextify_global_private_symbol` is no longer used. It was used to hold a new context's global object, but the approach has been changed to hold a ContextifyContext wrapper using `contextify_context_private_symbol`. Signed-off-by: Daeyeon Jeong <[email protected]> PR-URL: #45128 Refs: #44796 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Mohammed Keyvanzadeh <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Juan José Arboleda <[email protected]>