Initial child-process side plumbing for starting an embedded ServiceWorker context

content/renderer/service_worker/embedded_worker_dispatcher.cc

+// Copyright 2013 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 "content/renderer/service_worker/embedded_worker_dispatcher.h"
+
+#include "base/memory/scoped_ptr.h"
+#include "base/strings/string16.h"
+#include "base/strings/utf_string_conversions.h"
+#include "content/child/child_process.h"
+#include "content/child/thread_safe_sender.h"
+#include "content/common/service_worker_messages.h"
+#include "content/renderer/render_thread_impl.h"
+#include "content/renderer/service_worker/service_worker_context_client.h"
+#include "third_party/WebKit/public/platform/WebString.h"
+#include "third_party/WebKit/public/platform/WebURL.h"
+#include "third_party/WebKit/public/web/WebEmbeddedWorker.h"
+#include "third_party/WebKit/public/web/WebEmbeddedWorkerStartData.h"
+#include "webkit/child/worker_task_runner.h"
+#include "webkit/common/user_agent/user_agent.h"
+
+namespace content {
+
+static const int kMaxTimeForRunawayWorkerSeconds = 3;
+
+// A thin wrapper of WebEmbeddedWorker which also adds and releases process
+// references automatically.
+class EmbeddedWorkerDispatcher::WorkerWrapper {
+ public:
+  explicit WorkerWrapper(blink::WebEmbeddedWorker* worker)
+      : worker_(worker) {
+    ChildProcess::current()->AddRefProcess();
+  }
+
+  ~WorkerWrapper() {
+    ChildProcess::current()->ReleaseProcess();
+  }
+
+  blink::WebEmbeddedWorker* worker() { return worker_.get(); }
+
+ private:
+  scoped_ptr<blink::WebEmbeddedWorker> worker_;
+};
+
+EmbeddedWorkerDispatcher::EmbeddedWorkerDispatcher() : weak_factory_(this) {}
+
+EmbeddedWorkerDispatcher::~EmbeddedWorkerDispatcher() {}
+
+bool EmbeddedWorkerDispatcher::OnMessageReceived(
+    const IPC::Message& message) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(EmbeddedWorkerDispatcher, message)
+    IPC_MESSAGE_HANDLER(ServiceWorkerMsg_StartWorker, OnStartWorker)
+    IPC_MESSAGE_HANDLER(ServiceWorkerMsg_TerminateWorker, OnTerminateWorker)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+void EmbeddedWorkerDispatcher::WorkerContextDestroyed(
+    int32 embedded_worker_id) {
+  // There's a chance that this gets called multiple times.
+  // (And Remove internally DCHECK if we attempt to delete nonexistent one)
+  if (workers_.Lookup(embedded_worker_id))
+    workers_.Remove(embedded_worker_id);
+}
+
+void EmbeddedWorkerDispatcher::OnStartWorker(
+    const ServiceWorkerMsg_StartWorker_Params& params) {
+  DCHECK(!workers_.Lookup(params.embedded_worker_id));
+  scoped_ptr<WorkerWrapper> wrapper(new WorkerWrapper(
+      blink::WebEmbeddedWorker::create(
+          new ServiceWorkerContextClient(
+              params.embedded_worker_id,
+              params.service_worker_version_id,
+              params.script_url))));
+
+  // TODO(kinuko): Make sure if we want to load the script source from
+  // script_url in the worker context or not. For now I assume we simply
+  // receive the entire script source from the browser.
+  blink::WebEmbeddedWorkerStartData start_data;
+  start_data.scriptURL = params.script_url;
+  start_data.scriptSource = params.script_source;
+  start_data.userAgent =
+      base::UTF8ToUTF16(webkit_glue::GetUserAgent(params.script_url));
+  start_data.contentSecurityPolicy = params.content_security_policy;
+  start_data.contentSecurityPolicyType = params.content_security_policy_type;
+  start_data.startMode = params.start_mode;
+
+  wrapper->worker()->startWorkerContext(start_data);
+  workers_.AddWithID(wrapper.release(), params.embedded_worker_id);
+}
+
+void EmbeddedWorkerDispatcher::OnTerminateWorker(int32 embedded_worker_id) {
+  WorkerWrapper* wrapper = workers_.Lookup(embedded_worker_id);
+  if (!wrapper) {
+    LOG(WARNING) << "Got OnTerminateWorker for nonexistent worker";
+    return;
+  }
+  wrapper->worker()->terminateWorkerContext();
+
+  // Posts a delayed task to forcibly delete the worker instance to

[michaeln, 2013/11/13 00:31:37]

Why do this?

I guess the goal is to invoke ChildProcess::current()->ReleaseProcess() in a
timely fashion. We might want to invoke a WebEmbeddedWorker::abort() method in
this delayed task distinguish between usual destruction sequence (where the
context has unwound and such) and this unusual sequence.

[kinuko, 2013/11/18 14:09:48]

Yes, it's to make sure we terminate the worker context. Adding abort() sounds
good--- but let me postpone doing so and remove this part for now. (I wanted to
make sure we can add these hacks when necessary in this class structure too)

+  base::MessageLoop::current()->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&EmbeddedWorkerDispatcher::WorkerContextDestroyed,
+                 weak_factory_.GetWeakPtr(), embedded_worker_id),
+      base::TimeDelta::FromSeconds(kMaxTimeForRunawayWorkerSeconds));
+}
+
+}  // namespace content