[v22.x] vm: sync-ify SourceTextModule linkage by legendecas · Pull Request #60152 · nodejs/node

There are two phases in module linking: link, and instantiate. These
two operations are required to be separated to allow cyclic
dependencies.

`v8::Module::InstantiateModule` is only required to be invoked on the
root module. The global references created by `ModuleWrap::Link` are
only cleared at `ModuleWrap::Instantiate`. So the global references
created for depended modules are usually not cleared because
`ModuleWrap::Instantiate` is not invoked for each of depended modules,
and caused memory leak.

The change references the linked modules in an object internal slot.

This is not an issue for Node.js ESM support as these modules can not be
off-loaded. However, this could be outstanding for `vm.Module`.

PR-URL: #59117
Backport-PR-URL: #60152
Fixes: #50113
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

This allows overriding linked requests for a `ModuleWrap`. The
`statusOverride` in `vm.SourceTextModule` could call `moduleWrap.link`
a second time when `statusOverride` of `linking` is set to undefined.

Overriding of linked requests should be no harm but better to be
avoided. However, this will require a follow-up fix on `statusOverride`
in `vm.SourceTextModule`.

PR-URL: #59527
Backport-PR-URL: #60152
Fixes: #59480
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>

Split `module.link(linker)` into two synchronous step
`sourceTextModule.linkRequests()` and
`sourceTextModule.instantiate()`. This allows creating vm modules and
resolving the dependencies in a complete synchronous procedure.

This also makes `syntheticModule.link()` redundant. The link step for a
SyntheticModule is no-op and is already taken care in the constructor
by initializing the binding slots with the given export names.

PR-URL: #59000
Backport-PR-URL: #60152
Refs: #37648
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>