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Consolidate the require(...) primary implementation
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@jasnell
jasnell committed Nov 12, 2024
1 parent 24e808b commit 1f182f4
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Showing 3 changed files with 93 additions and 105 deletions.
45 changes: 5 additions & 40 deletions src/workerd/api/node/module.c++
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Original file line number Diff line number Diff line change
Expand Up @@ -81,48 +81,13 @@ jsg::JsValue ModuleUtil::createRequire(jsg::Lock& js, kj::String path) {
jsg::ModuleRegistry::ResolveMethod::REQUIRE, spec.asPtr()),
Error, "No such module \"", targetPath.toString(), "\".");

bool isEsm = info.maybeSynthetic == kj::none;

auto module = info.module.getHandle(js);

if (module->GetStatus() == v8::Module::Status::kEvaluating ||
module->GetStatus() == v8::Module::Status::kInstantiating) {
KJ_IF_SOME(synth, info.maybeSynthetic) {
KJ_IF_SOME(cjs, synth.tryGet<jsg::ModuleRegistry::CommonJsModuleInfo>()) {
return cjs.moduleContext->getExports(js);
}
KJ_IF_SOME(cjs, synth.tryGet<jsg::ModuleRegistry::NodeJsModuleInfo>()) {
return cjs.moduleContext->getExports(js);
}
}
}

auto features = FeatureFlags::get(js);
jsg::InstantiateModuleOptions options = jsg::InstantiateModuleOptions::DEFAULT;
if (features.getNoTopLevelAwaitInRequire()) {
options = jsg::InstantiateModuleOptions::NO_TOP_LEVEL_AWAIT;

// If the module was already evaluated, let's check if it is async.
// If it is, we will throw an error. This case can happen if a previous
// attempt to require the module failed because the module was async.
if (module->GetStatus() == v8::Module::kEvaluated) {
JSG_REQUIRE(!module->IsGraphAsync(), Error,
"Top-level await in module is not permitted at this time.");
}
}

jsg::instantiateModule(js, module, options);

if (isEsm) {
// If the import is an esm module, we will return the namespace object.
jsg::JsObject obj(module->GetModuleNamespace().As<v8::Object>());
if (obj.get(js, "__cjsUnwrapDefault"_kj) == js.boolean(true)) {
return obj.get(js, "default"_kj);
}
return obj;
jsg::ModuleRegistry::RequireImplOptions options =
jsg::ModuleRegistry::RequireImplOptions::DEFAULT;
if (info.maybeSynthetic != kj::none) {
options = jsg::ModuleRegistry::RequireImplOptions::EXPORT_DEFAULT;
}

return jsg::JsValue(js.v8Get(module->GetModuleNamespace().As<v8::Object>(), "default"_kj));
return jsg::ModuleRegistry::requireImpl(js, info, options);
}));
}

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145 changes: 80 additions & 65 deletions src/workerd/jsg/modules.c++
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Original file line number Diff line number Diff line change
Expand Up @@ -272,46 +272,12 @@ v8::Local<v8::Value> CommonJsModuleContext::require(jsg::Lock& js, kj::String sp
// Adding imported from suffix here not necessary like it is for resolveCallback, since we have a
// js stack that will include the parent module's name and location of the failed require().

auto module = info.module.getHandle(js);

if (module->GetStatus() == v8::Module::Status::kEvaluating ||
module->GetStatus() == v8::Module::Status::kInstantiating) {
KJ_IF_SOME(synth, info.maybeSynthetic) {
KJ_IF_SOME(cjs, synth.tryGet<ModuleRegistry::CommonJsModuleInfo>()) {
return cjs.moduleContext->getExports(js);
}
KJ_IF_SOME(cjs, synth.tryGet<ModuleRegistry::NodeJsModuleInfo>()) {
return cjs.moduleContext->getExports(js);
}
}
}

auto& isolateBase = IsolateBase::from(js.v8Isolate);
jsg::InstantiateModuleOptions options = jsg::InstantiateModuleOptions::DEFAULT;
if (!isolateBase.isTopLevelAwaitEnabled()) {
options = jsg::InstantiateModuleOptions::NO_TOP_LEVEL_AWAIT;

// If the module was already evaluated, let's check if it is async.
// If it is, we will throw an error. This case can happen if a previous
// attempt to require the module failed because the module was async.
if (module->GetStatus() == v8::Module::kEvaluated) {
JSG_REQUIRE(!module->IsGraphAsync(), Error,
"Top-level await in module is not permitted at this time.");
}
}

jsg::instantiateModule(js, module, options);

// Originally, This returned an object like `{default: module.exports}` when we really
// intended to return the module exports raw. We should be extracting `default` here.
// Unfortunately, there is a user depending on the wrong behavior in production, so we
// needed a compatibility flag to fix.
ModuleRegistry::RequireImplOptions options = ModuleRegistry::RequireImplOptions::DEFAULT;
if (getCommonJsExportDefault(js.v8Isolate)) {
return check(module->GetModuleNamespace().As<v8::Object>()->Get(
js.v8Context(), v8StrIntern(js.v8Isolate, "default")));
} else {
return module->GetModuleNamespace();
options = ModuleRegistry::RequireImplOptions::EXPORT_DEFAULT;
}

return ModuleRegistry::requireImpl(js, info, options);
}

v8::Local<v8::Value> NonModuleScript::runAndReturn(v8::Local<v8::Context> context) const {
Expand Down Expand Up @@ -615,33 +581,7 @@ v8::Local<v8::Value> NodeJsModuleContext::require(jsg::Lock& js, kj::String spec
info.maybeSynthetic, TypeError, "Cannot use require() to import an ES Module.");
}

auto module = info.module.getHandle(js);

JSG_REQUIRE(module->GetStatus() != v8::Module::Status::kEvaluating &&
module->GetStatus() != v8::Module::Status::kInstantiating,
Error,
"Module cannot be synchronously required while it is being instantiated or evaluated. "
"This error typically means that a CommonJS or NodeJS-Compat type module has a circular "
"dependency on itself, and that a synchronous require() is being called while the module "
"is being loaded.");

auto& isolateBase = IsolateBase::from(js.v8Isolate);
jsg::InstantiateModuleOptions options = jsg::InstantiateModuleOptions::DEFAULT;
if (!isolateBase.isTopLevelAwaitEnabled()) {
options = jsg::InstantiateModuleOptions::NO_TOP_LEVEL_AWAIT;

// If the module was already evaluated, let's check if it is async.
// If it is, we will throw an error. This case can happen if a previous
// attempt to require the module failed because the module was async.
if (module->GetStatus() == v8::Module::kEvaluated) {
JSG_REQUIRE(!module->IsGraphAsync(), Error,
"Top-level await in module is not permitted at this time.");
}
}

jsg::instantiateModule(js, module, options);

return js.v8Get(module->GetModuleNamespace().As<v8::Object>(), "default"_kj);
return ModuleRegistry::requireImpl(js, info, ModuleRegistry::RequireImplOptions::EXPORT_DEFAULT);
}

v8::Local<v8::Value> NodeJsModuleContext::getBuffer(jsg::Lock& js) {
Expand Down Expand Up @@ -712,4 +652,79 @@ kj::Maybe<kj::OneOf<kj::String, ModuleRegistry::ModuleInfo>> tryResolveFromFallb
return kj::none;
}

JsValue ModuleRegistry::requireImpl(Lock& js, ModuleInfo& info, RequireImplOptions options) {
auto module = info.module.getHandle(js);

// If the module status is evaluating or instantiating then the module is likely
// has a circular dependency on itself. If the module is a CommonJS or NodeJS
// module, we can return the exports object directly here.
if (module->GetStatus() == v8::Module::Status::kEvaluating ||
module->GetStatus() == v8::Module::Status::kInstantiating) {
KJ_IF_SOME(synth, info.maybeSynthetic) {
KJ_IF_SOME(cjs, synth.tryGet<ModuleRegistry::CommonJsModuleInfo>()) {
return JsValue(cjs.moduleContext->getExports(js));
}
KJ_IF_SOME(cjs, synth.tryGet<ModuleRegistry::NodeJsModuleInfo>()) {
return JsValue(cjs.moduleContext->getExports(js));
}
}
}

// When using require(...) we previously allowed the required modules to use
// top-level await. With a compat flag we disable use of top-level await but
// ONLY when the module is synchronously required. The same module being imported
// either statically or dynamically can still use TLA. This aligns with behavior
// being implemented in other JS runtimes.
auto& isolateBase = IsolateBase::from(js.v8Isolate);
jsg::InstantiateModuleOptions opts = jsg::InstantiateModuleOptions::DEFAULT;
if (!isolateBase.isTopLevelAwaitEnabled()) {
opts = jsg::InstantiateModuleOptions::NO_TOP_LEVEL_AWAIT;

// If the module was already evaluated, let's check if it is async.
// If it is, we will throw an error. This case can happen if a previous
// attempt to require the module failed because the module was async.
if (module->GetStatus() == v8::Module::kEvaluated) {
JSG_REQUIRE(!module->IsGraphAsync(), Error,
"Top-level await in module is not permitted at this time.");
}
}

jsg::instantiateModule(js, module, opts);

if (info.maybeSynthetic == kj::none) {
// If the module is an ESM and the __cjsUnwrapDefault flag is set to true, we will
// always return the default export regardless of the options.
// Otherwise fallback to the options. This is an early version of the "module.exports"
// convention that Node.js finally adopted for require(esm) that was not officially
// adopted but there are a handful of modules in the ecosystem that supported it
// early. It's trivial for us to support here so let's just do so.
JsObject obj(module->GetModuleNamespace().As<v8::Object>());
if (obj.get(js, "__cjsUnwrapDefault"_kj) == js.boolean(true)) {
return obj.get(js, "default"_kj);
}
// If the ES Module namespace exports a "module.exports" key then that will be the
// export that is returned by the require(...) call per Node.js' recently added
// require(esm) support.
// See: https://nodejs.org/docs/latest/api/modules.html#loading-ecmascript-modules-using-require
if (obj.has(js, "module.exports"_kj)) {
// We only want to return the value if it is explicitly specified, otherwise we'll
// always be returning undefined.
return obj.get(js, "module.exports"_kj);
}
}

// Originally, require returned an object like `{default: module.exports}` when we really
// intended to return the module exports raw. We should be extracting `default` here.
// When Node.js recently finally adopted require(esm), they adopted the default behavior
// of exporting the module namespace, which is fun. We'll stick with our default here for
// now but users can get Node.js-like behavior by switching off the
// exportCommonJsDefaultNamespace compat flag.
if (options == RequireImplOptions::EXPORT_DEFAULT) {
return JsValue(check(module->GetModuleNamespace().As<v8::Object>()->Get(
js.v8Context(), v8StrIntern(js.v8Isolate, "default"))));
}

return JsValue(module->GetModuleNamespace());
}

} // namespace workerd::jsg
8 changes: 8 additions & 0 deletions src/workerd/jsg/modules.h
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Original file line number Diff line number Diff line change
Expand Up @@ -403,6 +403,14 @@ class ModuleRegistry {
using DynamicImportCallback = Promise<Value>(jsg::Lock& js, kj::Function<Value()> handler);

virtual void setDynamicImportCallback(kj::Function<DynamicImportCallback> func) = 0;

enum class RequireImplOptions {
DEFAULT,
EXPORT_DEFAULT,
};

static JsValue requireImpl(
Lock& js, ModuleInfo& info, RequireImplOptions options = RequireImplOptions::DEFAULT);
};

template <typename TypeWrapper>
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