Worklet: Lazily create PaintWorkletGlobalScopes

third_party/WebKit/Source/core/workers/MainThreadWorklet.cpp

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/workers/MainThreadWorklet.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/ScriptSourceCode.h"
 #include "bindings/core/v8/V8BindingForCore.h"
 #include "core/frame/LocalFrame.h"
@@ skipping 15 matching lines @@
   if (credentials_option == "include")
     return WebURLRequest::kFetchCredentialsModeInclude;
   NOTREACHED();
   return WebURLRequest::kFetchCredentialsModeOmit;
 }
 
 }  // namespace
 
 MainThreadWorklet::MainThreadWorklet(LocalFrame* frame) : Worklet(frame) {}
 
+WorkletGlobalScopeProxy* MainThreadWorklet::FindAvailableGlobalScope() const {
+  DCHECK(IsMainThread());
+  // TODO(nhiroki): Support the case where there are multiple global scopes.
+  DCHECK_EQ(1u, GetNumberOfGlobalScopes());
+  return proxies_.begin()->get();
+}
+
 // Implementation of the second half of the "addModule(moduleURL, options)"
 // algorithm:
 // https://drafts.css-houdini.org/worklets/#dom-worklet-addmodule
 void MainThreadWorklet::FetchAndInvokeScript(const KURL& module_url_record,
                                              const WorkletOptions& options,
                                              ScriptPromiseResolver* resolver) {
   DCHECK(IsMainThread());
   if (!GetExecutionContext())
     return;
 
@@ skipping 14 matching lines @@
   // type."
   // workletGlobalScopeType is encoded into the class name (e.g., PaintWorklet).
 
   // Step 10: "If the worklet's WorkletGlobalScopes is empty, run the following
   // steps:"
   //   10.1: "Create a WorkletGlobalScope given workletGlobalScopeType,
   //          moduleResponsesMap, and outsideSettings."
   //   10.2: "Add the WorkletGlobalScope to worklet's WorkletGlobalScopes."
   // "Depending on the type of worklet the user agent may create additional
   // WorkletGlobalScopes at this time."
-  // TODO(nhiroki): Create WorkletGlobalScopes at this point.
+  while (NeedsToCreateGlobalScope())
+    proxies_.insert(CreateGlobalScope());
+  DCHECK_LT(0u, GetNumberOfGlobalScopes());

[haraken, 2017/05/29 07:38:48]

DCHECK_EQ(1, GetNumberOfGlobalScopes()) at the moment?

[nhiroki, 2017/05/29 08:52:00]

Done.

 
   // Step 11: "Let pendingTaskStruct be a new pending tasks struct with counter
   // initialized to the length of worklet's WorkletGlobalScopes."
-  // TODO(nhiroki): Introduce the concept of "worklet's WorkletGlobalScopes" and
-  // use the length of it here.
-  constexpr int number_of_global_scopes = 1;
   WorkletPendingTasks* pending_tasks =
-      new WorkletPendingTasks(number_of_global_scopes, resolver);
+      new WorkletPendingTasks(GetNumberOfGlobalScopes(), resolver);
 
   // Step 12: "For each workletGlobalScope in the worklet's
   // WorkletGlobalScopes, queue a task on the workletGlobalScope to fetch and
   // invoke a worklet script given workletGlobalScope, moduleURLRecord,
   // moduleResponsesMap, credentialOptions, outsideSettings, pendingTaskStruct,
   // and promise."
   // TODO(nhiroki): Queue a task instead of executing this here.
-  GetWorkletGlobalScopeProxy()->FetchAndInvokeScript(
-      module_url_record, credentials_mode, pending_tasks);
+  for (const auto& proxy : proxies_) {
+    proxy->FetchAndInvokeScript(module_url_record, credentials_mode,
+                                pending_tasks);
+  }
 }
 
 void MainThreadWorklet::ContextDestroyed(ExecutionContext* execution_context) {
   DCHECK(IsMainThread());
-  GetWorkletGlobalScopeProxy()->TerminateWorkletGlobalScope();
+  for (const auto& proxy : proxies_)
+    proxy->TerminateWorkletGlobalScope();
 }
 
 DEFINE_TRACE(MainThreadWorklet) {
   Worklet::Trace(visitor);
 }
 
 }  // namespace blink