Bug 1875836 - Part 2: Support dynamic import in ComponentModuleLoader. r=jonco

Differential Revision: https://phabricator.services.mozilla.com/D199279

js/loader/ModuleLoaderBase.cpp

@@ -335,7 +335,11 @@ bool ModuleLoaderBase::HostImportModuleDynamically(
     return false;
   }
 
-  loader->StartDynamicImport(request);
+  nsresult rv = loader->StartDynamicImport(request);
+  if (NS_SUCCEEDED(rv)) {
+    loader->OnDynamicImportStarted(request);
+  }
+
   return true;
 }
 
@@ -898,7 +902,7 @@ void ModuleLoadRequest::ChildLoadComplete(bool aSuccess) {
   }
 }
 
-void ModuleLoaderBase::StartDynamicImport(ModuleLoadRequest* aRequest) {
+nsresult ModuleLoaderBase::StartDynamicImport(ModuleLoadRequest* aRequest) {
   MOZ_ASSERT(aRequest->mLoader == this);
 
   LOG(("ScriptLoadRequest (%p): Start dynamic import", aRequest));
@@ -910,6 +914,7 @@ void ModuleLoaderBase::StartDynamicImport(ModuleLoadRequest* aRequest) {
     mLoader->ReportErrorToConsole(aRequest, rv);
     FinishDynamicImportAndReject(aRequest, rv);
   }
+  return rv;
 }
 
 void ModuleLoaderBase::FinishDynamicImportAndReject(ModuleLoadRequest* aRequest,

js/loader/ModuleLoaderBase.h

@@ -200,6 +200,12 @@ class ModuleLoaderBase : public nsISupports {
 
   virtual ~ModuleLoaderBase();
 
+#ifdef DEBUG
+  const ScriptLoadRequestList& DynamicImportRequests() const {
+    return mDynamicImportRequests;
+  }
+#endif
+
  public:
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_CLASS(ModuleLoaderBase)
@@ -234,6 +240,9 @@ class ModuleLoaderBase : public nsISupports {
       JSContext* aCx, nsIURI* aURI, LoadedScript* aMaybeActiveScript,
       JS::Handle<JSString*> aSpecifier, JS::Handle<JSObject*> aPromise) = 0;
 
+  // Called when dynamic import started successfully.
+  virtual void OnDynamicImportStarted(ModuleLoadRequest* aRequest) {}
+
   // Check whether we can load a module. May return false with |aRvOut| set to
   // NS_OK to abort load without returning an error.
   virtual bool CanStartLoad(ModuleLoadRequest* aRequest, nsresult* aRvOut) = 0;
@@ -298,7 +307,7 @@ class ModuleLoaderBase : public nsISupports {
   nsresult EvaluateModuleInContext(JSContext* aCx, ModuleLoadRequest* aRequest,
                                    JS::ModuleErrorBehaviour errorBehaviour);
 
-  void StartDynamicImport(ModuleLoadRequest* aRequest);
+  nsresult StartDynamicImport(ModuleLoadRequest* aRequest);
   void ProcessDynamicImport(ModuleLoadRequest* aRequest);
   void CancelAndClearDynamicImports();
 

js/xpconnect/loader/ComponentModuleLoader.cpp

@@ -76,7 +76,56 @@ already_AddRefed<ModuleLoadRequest> ComponentModuleLoader::CreateStaticImport(
 already_AddRefed<ModuleLoadRequest> ComponentModuleLoader::CreateDynamicImport(
     JSContext* aCx, nsIURI* aURI, LoadedScript* aMaybeActiveScript,
     JS::Handle<JSString*> aSpecifier, JS::Handle<JSObject*> aPromise) {
-  return nullptr;  // Not yet implemented.
+  RefPtr<ComponentLoadContext> context = new ComponentLoadContext();
+  RefPtr<ModuleLoadRequest> request = new ModuleLoadRequest(
+      aURI, aMaybeActiveScript->ReferrerPolicy(),
+      aMaybeActiveScript->GetFetchOptions(), dom::SRIMetadata(),
+      aMaybeActiveScript->BaseURL(), context,
+      /* aIsTopLevel = */ true, /* aIsDynamicImport =  */ true, this,
+      ModuleLoadRequest::NewVisitedSetForTopLevelImport(aURI), nullptr);
+
+  request->SetDynamicImport(aMaybeActiveScript, aSpecifier, aPromise);
+  request->NoCacheEntryFound();
+
+  return request.forget();
+}
+
+void ComponentModuleLoader::OnDynamicImportStarted(
+    ModuleLoadRequest* aRequest) {
+  MOZ_ASSERT(aRequest->IsDynamicImport());
+  MOZ_ASSERT(!mLoadRequests.Contains(aRequest));
+
+  if (aRequest->IsFetching()) {
+    // This module is newly imported.
+    //
+    // DynamicImportRequests() can contain multiple requests when a dynamic
+    // import is performed while evaluating the top-level script of other
+    // dynamic imports.
+    //
+    // mLoadRequests should be empty given evaluation is performed after
+    // handling all fetching requests.
+    MOZ_ASSERT(DynamicImportRequests().Contains(aRequest));
+    MOZ_ASSERT(mLoadRequests.isEmpty());
+
+    nsresult rv = OnFetchComplete(aRequest, NS_OK);
+    if (NS_FAILED(rv)) {
+      mLoadRequests.CancelRequestsAndClear();
+      CancelDynamicImport(aRequest, rv);
+      return;
+    }
+
+    rv = ProcessRequests();
+    if (NS_FAILED(rv)) {
+      CancelDynamicImport(aRequest, rv);
+      return;
+    }
+  } else {
+    // This module had already been imported.
+    MOZ_ASSERT(DynamicImportRequests().isEmpty());
+    MOZ_ASSERT(mLoadRequests.isEmpty());
+  }
+
+  ProcessDynamicImport(aRequest);
 }
 
 bool ComponentModuleLoader::CanStartLoad(ModuleLoadRequest* aRequest,
@@ -150,7 +199,10 @@ nsresult ComponentModuleLoader::StartFetch(ModuleLoadRequest* aRequest) {
     context->mScript = script;
   }
 
-  mLoadRequests.AppendElement(aRequest);
+  if (!aRequest->IsDynamicImport()) {
+    // NOTE: Dynamic import is stored into mDynamicImportRequests.
+    mLoadRequests.AppendElement(aRequest);
+  }
 
   return NS_OK;
 }

js/xpconnect/loader/ComponentModuleLoader.h

@@ -73,6 +73,8 @@ class ComponentModuleLoader : public JS::loader::ModuleLoaderBase {
       JS::Handle<JSString*> aSpecifier,
       JS::Handle<JSObject*> aPromise) override;
 
+  void OnDynamicImportStarted(ModuleLoadRequest* aRequest) override;
+
   bool CanStartLoad(ModuleLoadRequest* aRequest, nsresult* aRvOut) override;
 
   nsresult StartFetch(ModuleLoadRequest* aRequest) override;