Refactor the daemon controller so that the callbacks are called on the caller thread.

remoting/host/setup/daemon_controller.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 "remoting/host/setup/daemon_controller.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/single_thread_task_runner.h"
+#include "base/thread_task_runner_handle.h"
+#include "base/values.h"
+#include "remoting/base/auto_thread.h"
+#include "remoting/base/auto_thread_task_runner.h"
+
+namespace remoting {
+
+// Name of the Daemon Controller's worker thread.
+const char kDaemonControllerThreadName[] = "Daemon Controller thread";
+
+DaemonController::DaemonController(scoped_ptr<Delegate> delegate)
+    : caller_task_runner_(base::ThreadTaskRunnerHandle::Get()),
+      delegate_(delegate.Pass()) {
+  // Launch the delegate thread.
+  delegate_thread_.reset(new AutoThread(kDaemonControllerThreadName));
+#if defined(OS_WIN)
+  delegate_thread_->SetComInitType(AutoThread::COM_INIT_STA);
+  delegate_task_runner_ =
+      delegate_thread_->StartWithType(base::MessageLoop::TYPE_UI);
+#else
+  delegate_task_runner_ =
+      delegate_thread_->StartWithType(base::MessageLoop::TYPE_DEFAULT);
+#endif
+}
+
+DaemonController::State DaemonController::GetState() {
+  DCHECK(caller_task_runner_->BelongsToCurrentThread());
+  return delegate_->GetState();
+}
+
+void DaemonController::GetConfig(const GetConfigCallback& done) {
+  DCHECK(caller_task_runner_->BelongsToCurrentThread());
+
+  DaemonController::GetConfigCallback wrapped_done = base::Bind(
+      &DaemonController::InvokeConfigCallbackAndScheduleNext, this, done);
+  base::Closure request = base::Bind(
+      &DaemonController::DoGetConfig, this, wrapped_done);
+  ServiceOrQueueRequest(request);
+}
+
+void DaemonController::SetConfigAndStart(
+    scoped_ptr<base::DictionaryValue> config,
+    bool consent,
+    const CompletionCallback& done) {
+  DCHECK(caller_task_runner_->BelongsToCurrentThread());
+
+  DaemonController::CompletionCallback wrapped_done = base::Bind(
+      &DaemonController::InvokeCompletionCallbackAndScheduleNext, this, done);
+  base::Closure request = base::Bind(
+      &DaemonController::DoSetConfigAndStart, this, base::Passed(&config),
+      consent, wrapped_done);
+  ServiceOrQueueRequest(request);
+}
+
+void DaemonController::UpdateConfig(scoped_ptr<base::DictionaryValue> config,
+                                    const CompletionCallback& done) {
+  DCHECK(caller_task_runner_->BelongsToCurrentThread());
+
+  DaemonController::CompletionCallback wrapped_done = base::Bind(
+      &DaemonController::InvokeCompletionCallbackAndScheduleNext, this, done);
+  base::Closure request = base::Bind(
+      &DaemonController::DoUpdateConfig, this, base::Passed(&config),
+      wrapped_done);
+  ServiceOrQueueRequest(request);
+}
+
+void DaemonController::Stop(const CompletionCallback& done) {
+  DCHECK(caller_task_runner_->BelongsToCurrentThread());
+
+  DaemonController::CompletionCallback wrapped_done = base::Bind(
+      &DaemonController::InvokeCompletionCallbackAndScheduleNext, this, done);
+  base::Closure request = base::Bind(
+      &DaemonController::DoStop, this, wrapped_done);
+  ServiceOrQueueRequest(request);
+}
+
+void DaemonController::SetWindow(void* window_handle) {
+  DCHECK(caller_task_runner_->BelongsToCurrentThread());
+
+  base::Closure done = base::Bind(&DaemonController::ScheduleNext, this);
+  base::Closure request = base::Bind(
+      &DaemonController::DoSetWindow, this, window_handle, done);
+  ServiceOrQueueRequest(request);
+}
+
+void DaemonController::GetVersion(const GetVersionCallback& done) {
+  DCHECK(caller_task_runner_->BelongsToCurrentThread());
+
+  DaemonController::GetVersionCallback wrapped_done = base::Bind(
+      &DaemonController::InvokeVersionCallbackAndScheduleNext, this, done);
+  base::Closure request = base::Bind(
+      &DaemonController::DoGetVersion, this, wrapped_done);
+  ServiceOrQueueRequest(request);
+}
+
+void DaemonController::GetUsageStatsConsent(
+    const GetUsageStatsConsentCallback& done) {
+  DCHECK(caller_task_runner_->BelongsToCurrentThread());
+
+  DaemonController::GetUsageStatsConsentCallback wrapped_done = base::Bind(
+      &DaemonController::InvokeConsentCallbackAndScheduleNext, this, done);
+  base::Closure request = base::Bind(
+      &DaemonController::DoGetUsageStatsConsent, this, wrapped_done);
+  ServiceOrQueueRequest(request);
+}
+
+DaemonController::~DaemonController() {
+  // Make sure |delegate_| is deleted on the background thread.
+  delegate_task_runner_->DeleteSoon(FROM_HERE, delegate_.release());
+
+  // Stop the thread.
+  delegate_task_runner_ = NULL;
+  caller_task_runner_->DeleteSoon(FROM_HERE, delegate_thread_.release());
+}
+
+void DaemonController::DoGetConfig(const GetConfigCallback& done) {
+  if (!delegate_task_runner_->BelongsToCurrentThread()) {

[Sergey Ulanov, 2013/09/09 18:12:31]

Here and in other Do*() methods you can replace it with a DCHECK.

[alexeypa (please no reviews), 2013/09/09 19:30:57]

Only if DaemonController::ServiceNextRequest() posts a tasks instead of running
closure directly. Done.

+    delegate_task_runner_->PostTask(
+        FROM_HERE, base::Bind(&DaemonController::DoGetConfig, this, done));
+    return;
+  }
+
+  scoped_ptr<base::DictionaryValue> config = delegate_->GetConfig();
+  caller_task_runner_->PostTask(FROM_HERE,
+                                base::Bind(done, base::Passed(&config)));
+}
+
+void DaemonController::DoSetConfigAndStart(
+    scoped_ptr<base::DictionaryValue> config,
+    bool consent,
+    const CompletionCallback& done) {
+  if (!delegate_task_runner_->BelongsToCurrentThread()) {
+    delegate_task_runner_->PostTask(
+        FROM_HERE, base::Bind(&DaemonController::DoSetConfigAndStart, this,
+                              base::Passed(&config), consent, done));
+    return;
+  }
+
+  delegate_->SetConfigAndStart(config.Pass(), consent, done);
+}
+
+void DaemonController::DoUpdateConfig(
+    scoped_ptr<base::DictionaryValue> config,
+    const CompletionCallback& done) {
+  if (!delegate_task_runner_->BelongsToCurrentThread()) {
+    delegate_task_runner_->PostTask(
+        FROM_HERE, base::Bind(&DaemonController::DoUpdateConfig, this,
+                              base::Passed(&config), done));
+    return;
+  }
+
+  delegate_->UpdateConfig(config.Pass(), done);
+}
+
+void DaemonController::DoStop(const CompletionCallback& done) {
+  if (!delegate_task_runner_->BelongsToCurrentThread()) {
+    delegate_task_runner_->PostTask(
+        FROM_HERE, base::Bind(&DaemonController::DoStop, this, done));
+    return;
+  }
+
+  delegate_->Stop(done);
+}
+
+void DaemonController::DoSetWindow(void* window_handle,
+                                   const base::Closure& done) {
+  if (!delegate_task_runner_->BelongsToCurrentThread()) {
+    delegate_task_runner_->PostTask(
+        FROM_HERE, base::Bind(&DaemonController::DoSetWindow, this,
+                              window_handle, done));
+    return;
+  }
+
+  delegate_->SetWindow(window_handle);
+  caller_task_runner_->PostTask(FROM_HERE, done);
+}
+
+void DaemonController::DoGetVersion(const GetVersionCallback& done) {
+  if (!delegate_task_runner_->BelongsToCurrentThread()) {
+    delegate_task_runner_->PostTask(
+        FROM_HERE, base::Bind(&DaemonController::DoGetVersion, this, done));
+    return;
+  }
+
+  std::string version = delegate_->GetVersion();
+  caller_task_runner_->PostTask(FROM_HERE, base::Bind(done, version));
+}
+
+void DaemonController::DoGetUsageStatsConsent(
+    const GetUsageStatsConsentCallback& done) {
+  if (!delegate_task_runner_->BelongsToCurrentThread()) {
+    delegate_task_runner_->PostTask(
+        FROM_HERE, base::Bind(&DaemonController::DoGetUsageStatsConsent, this,
+                              done));
+    return;
+  }
+
+  DaemonController::UsageStatsConsent consent =
+      delegate_->GetUsageStatsConsent();
+  caller_task_runner_->PostTask(FROM_HERE, base::Bind(done, consent));
+}
+
+void DaemonController::InvokeCompletionCallbackAndScheduleNext(
+    const CompletionCallback& done,
+    AsyncResult result) {
+  if (!caller_task_runner_->BelongsToCurrentThread()) {
+    caller_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&DaemonController::InvokeCompletionCallbackAndScheduleNext,
+                   this, done, result));
+    return;
+  }
+
+  done.Run(result);
+  ScheduleNext();
+}
+
+void DaemonController::InvokeConfigCallbackAndScheduleNext(
+    const GetConfigCallback& done,
+    scoped_ptr<base::DictionaryValue> config) {
+  DCHECK(caller_task_runner_->BelongsToCurrentThread());
+
+  done.Run(config.Pass());
+  ScheduleNext();
+}
+
+void DaemonController::InvokeConsentCallbackAndScheduleNext(
+    const GetUsageStatsConsentCallback& done,
+    const UsageStatsConsent& consent) {
+  DCHECK(caller_task_runner_->BelongsToCurrentThread());
+
+  done.Run(consent);
+  ScheduleNext();
+}
+
+void DaemonController::InvokeVersionCallbackAndScheduleNext(
+    const GetVersionCallback& done,
+    const std::string& version) {
+  DCHECK(caller_task_runner_->BelongsToCurrentThread());
+
+  done.Run(version);
+  ScheduleNext();
+}
+
+void DaemonController::ScheduleNext() {
+  DCHECK(caller_task_runner_->BelongsToCurrentThread());
+
+  pending_requests_.pop();
+  ServiceNextRequest();
+}
+
+void DaemonController::ServiceOrQueueRequest(const base::Closure& request) {
+  bool servicing_request = !pending_requests_.empty();
+  pending_requests_.push(request);
+  if (!servicing_request)
+    ServiceNextRequest();
+}
+
+void DaemonController::ServiceNextRequest() {
+  if (!pending_requests_.empty())
+    pending_requests_.front().Run();
+}
+
+}  // namespace remoting