Add base::RunLoop and update ui_test_utils to use it to reduce flakiness

base/message_loop.cc

 // Copyright (c) 2012 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 "base/message_loop.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 113 matching lines @@
 MessageLoop::DestructionObserver::~DestructionObserver() {
 }
 
 //------------------------------------------------------------------------------
 
 MessageLoop::MessageLoop(Type type)
     : type_(type),
       nestable_tasks_allowed_(true),
       exception_restoration_(false),
       message_histogram_(NULL),
-      state_(NULL),
 #ifdef OS_WIN
       os_modal_loop_(false),
 #endif  // OS_WIN
       next_sequence_num_(0) {
   DCHECK(!current()) << "should only have one message loop per thread";
   lazy_tls_ptr.Pointer()->Set(this);
 
   message_loop_proxy_ = new base::MessageLoopProxyImpl();
   thread_task_runner_handle_.reset(
       new base::ThreadTaskRunnerHandle(message_loop_proxy_));
@@ skipping 28 matching lines @@
     pump_ = MESSAGE_PUMP_IO;
   } else {
     DCHECK_EQ(TYPE_DEFAULT, type_);
     pump_ = new base::MessagePumpDefault();
   }
 }
 
 MessageLoop::~MessageLoop() {
   DCHECK_EQ(this, current());
 
-  DCHECK(!state_);
+  DCHECK(!run_loop_);
 
   // Clean up any unprocessed tasks, but take care: deleting a task could
   // result in the addition of more tasks (e.g., via DeleteSoon).  We set a
   // limit on the number of times we will allow a deleted task to generate more
   // tasks.  Normally, we should only pass through this loop once or twice.  If
   // we end up hitting the loop limit, then it is probably due to one task that
   // is being stubborn.  Inspect the queues to see who is left.
   bool did_work;
   for (int i = 0; i < 100; ++i) {
     DeletePendingTasks();
@@ skipping 91 matching lines @@
 void MessageLoop::PostNonNestableDelayedTask(
     const tracked_objects::Location& from_here,
     const base::Closure& task,
     TimeDelta delay) {
   DCHECK(!task.is_null()) << from_here.ToString();
   PendingTask pending_task(
       from_here, task, CalculateDelayedRuntime(delay), false);
   AddToIncomingQueue(&pending_task);
 }
 
+MessageLoop::RunLoop::RunLoop()
+    : loop_(MessageLoop::current()),
+      run_called_(false),
+      stop_called_(false),
+      running_(false),
+      run_depth_(0),
+      quit_when_idle_received_(false) {
+#if !defined(OS_MACOSX) && !defined(OS_ANDROID)
+   dispatcher_ = NULL;
+#endif
+}
+
+#if !defined(OS_MACOSX) && !defined(OS_ANDROID)
+MessageLoop::RunLoop::RunLoop(Dispatcher* dispatcher)
+    : loop_(MessageLoop::current()),
+      run_called_(false),
+      stop_called_(false),
+      running_(false),
+      run_depth_(0),
+      quit_when_idle_received_(false),
+      dispatcher_(dispatcher) {
+}
+#endif
+
+MessageLoop::RunLoop::~RunLoop() {
+}
+
+void MessageLoop::RunLoop::Run() {
+  DCHECK(!run_called_);
+  run_called_ = true;
+
+  // Allow Stop to be called before Run (why not?).
+  if (stop_called_)
+    return;
+
+  // Push RunLoop stack:
+  base::WeakPtr<RunLoop> previous_run_loop = loop_->run_loop_;
+  run_depth_ = previous_run_loop? previous_run_loop->run_depth_ + 1 : 1;
+  loop_->run_loop_ = AsWeakPtr();
+
+  running_ = true;
+  loop_->RunHandler();
+  running_ = false;
+
+  // Pop RunLoop stack:
+  loop_->run_loop_ = previous_run_loop;
+
+  // Execute deferred QuitNow, if any:
+  if (previous_run_loop && previous_run_loop->stop_called_)
+    loop_->QuitNow();
+}
+
+void MessageLoop::RunLoop::RunUntilIdle() {
+  quit_when_idle_received_ = true;
+  Run();
+}
+
+void MessageLoop::RunLoop::Stop() {
+  stop_called_ = true;
+  if (running_ && loop_->run_loop_ == this) {
+    // This is the inner-most RunLoop, so quit now.
+    loop_->QuitNow();
+  }
+}
+
+base::Closure MessageLoop::RunLoop::StopClosure() {
+  return base::Bind(&RunLoop::Stop, AsWeakPtr());
+}
+
 void MessageLoop::Run() {
-  AutoRunState save_state(this);
-  RunHandler();
+  RunLoop run_loop;
+  run_loop.Run();
 }
 
 void MessageLoop::RunAllPending() {
-  AutoRunState save_state(this);
-  state_->quit_received = true;  // Means run until we would otherwise block.
-  RunHandler();
+  RunLoop run_loop;
+  run_loop.RunUntilIdle();
 }
 
-void MessageLoop::Quit() {
+void MessageLoop::QuitWhenIdle() {
   DCHECK_EQ(this, current());
-  if (state_) {
-    state_->quit_received = true;
+  if (run_loop_) {
+    run_loop_->quit_when_idle_received_ = true;
   } else {
     NOTREACHED() << "Must be inside Run to call Quit";
   }
 }
 
 void MessageLoop::QuitNow() {
   DCHECK_EQ(this, current());
-  if (state_) {
+  if (run_loop_) {
     pump_->Quit();
   } else {
     NOTREACHED() << "Must be inside Run to call Quit";
   }
 }
 
-static void QuitCurrent() {
-  MessageLoop::current()->Quit();
+static void QuitCurrentWhenIdle() {
+  MessageLoop::current()->QuitWhenIdle();
 }
 
 // static
-base::Closure MessageLoop::QuitClosure() {
-  return base::Bind(&QuitCurrent);
+base::Closure MessageLoop::QuitWhenIdleClosure() {
+  return base::Bind(&QuitCurrentWhenIdle);
 }
 
 void MessageLoop::SetNestableTasksAllowed(bool allowed) {
   if (nestable_tasks_allowed_ != allowed) {
     nestable_tasks_allowed_ = allowed;
     if (!nestable_tasks_allowed_)
       return;
     // Start the native pump if we are not already pumping.
     pump_->ScheduleWork();
   }
 }
 
 bool MessageLoop::NestableTasksAllowed() const {
   return nestable_tasks_allowed_;
 }
 
 bool MessageLoop::IsNested() {
-  return state_->run_depth > 1;
+  return run_loop_->run_depth_ > 1;
 }
 
 void MessageLoop::AddTaskObserver(TaskObserver* task_observer) {
   DCHECK_EQ(this, current());
   task_observers_.AddObserver(task_observer);
 }
 
 void MessageLoop::RemoveTaskObserver(TaskObserver* task_observer) {
   DCHECK_EQ(this, current());
   task_observers_.RemoveObserver(task_observer);
 }
 
 void MessageLoop::AssertIdle() const {
   // We only check |incoming_queue_|, since we don't want to lock |work_queue_|.
   base::AutoLock lock(incoming_queue_lock_);
   DCHECK(incoming_queue_.empty());
 }
 
 bool MessageLoop::is_running() const {
   DCHECK_EQ(this, current());
-  return state_ != NULL;
+  return !!run_loop_;
 }
 
 //------------------------------------------------------------------------------
 
 // Runs the loop in two different SEH modes:
 // enable_SEH_restoration_ = false : any unhandled exception goes to the last
 // one that calls SetUnhandledExceptionFilter().
 // enable_SEH_restoration_ = true : any unhandled exception goes to the filter
 // that was existed before the loop was run.
 void MessageLoop::RunHandler() {
@@ skipping 17 matching lines @@
   return;
 }
 #endif
 
 void MessageLoop::RunInternal() {
   DCHECK_EQ(this, current());
 
   StartHistogrammer();
 
 #if !defined(OS_MACOSX) && !defined(OS_ANDROID)
-  if (state_->dispatcher && type() == TYPE_UI) {
+  if (run_loop_->dispatcher_ && type() == TYPE_UI) {
     static_cast<base::MessagePumpForUI*>(pump_.get())->
-        RunWithDispatcher(this, state_->dispatcher);
+        RunWithDispatcher(this, run_loop_->dispatcher_);
     return;
   }
 #endif
 
   pump_->Run(this);
 }
 
 bool MessageLoop::ProcessNextDelayedNonNestableTask() {
-  if (state_->run_depth != 1)
-    return false;
-
   if (deferred_non_nestable_work_queue_.empty())
     return false;
 
+  if (run_loop_->run_depth_ != 1)

[jbates, 2012/06/22 02:12:51]

Moved this down here, because it's cheaper to check if the queue is empty than
to access a WeakPtr...

+    return false;
+
   PendingTask pending_task = deferred_non_nestable_work_queue_.front();
   deferred_non_nestable_work_queue_.pop();
 
   RunTask(pending_task);
   return true;
 }
 
 void MessageLoop::RunTask(const PendingTask& pending_task) {
   TRACE_EVENT2("task", "MessageLoop::RunTask",
                "src_file", pending_task.posted_from.file_name(),
@@ skipping 22 matching lines @@
   FOR_EACH_OBSERVER(TaskObserver, task_observers_,
                     DidProcessTask(pending_task.time_posted));
 
   tracked_objects::ThreadData::TallyRunOnNamedThreadIfTracking(pending_task,
       start_time, tracked_objects::ThreadData::NowForEndOfRun());
 
   nestable_tasks_allowed_ = true;
 }
 
 bool MessageLoop::DeferOrRunPendingTask(const PendingTask& pending_task) {
-  if (pending_task.nestable || state_->run_depth == 1) {
+  if (pending_task.nestable || run_loop_->run_depth_ == 1) {
     RunTask(pending_task);
     // Show that we ran a task (Note: a new one might arrive as a
     // consequence!).
     return true;
   }
 
   // We couldn't run the task now because we're in a nested message loop
   // and the task isn't nestable.
   deferred_non_nestable_work_queue_.push(pending_task);
   return false;
@@ skipping 201 matching lines @@
   if (!delayed_work_queue_.empty())
     *next_delayed_work_time = delayed_work_queue_.top().delayed_run_time;
 
   return DeferOrRunPendingTask(pending_task);
 }
 
 bool MessageLoop::DoIdleWork() {
   if (ProcessNextDelayedNonNestableTask())
     return true;
 
-  if (state_->quit_received)
+  if (run_loop_->quit_when_idle_received_)
     pump_->Quit();
 
   return false;
 }
 
 void MessageLoop::DeleteSoonInternal(const tracked_objects::Location& from_here,
                                      void(*deleter)(const void*),
                                      const void* object) {
   PostNonNestableTask(from_here, base::Bind(deleter, object));
 }
 
 void MessageLoop::ReleaseSoonInternal(
     const tracked_objects::Location& from_here,
     void(*releaser)(const void*),
     const void* object) {
   PostNonNestableTask(from_here, base::Bind(releaser, object));
 }
 
 //------------------------------------------------------------------------------
-// MessageLoop::AutoRunState
-
-MessageLoop::AutoRunState::AutoRunState(MessageLoop* loop) : loop_(loop) {
-  // Make the loop reference us.
-  previous_state_ = loop_->state_;
-  if (previous_state_) {
-    run_depth = previous_state_->run_depth + 1;
-  } else {
-    run_depth = 1;
-  }
-  loop_->state_ = this;
-
-  // Initialize the other fields:
-  quit_received = false;
-#if !defined(OS_MACOSX) && !defined(OS_ANDROID)
-  dispatcher = NULL;
-#endif
-}
-
-MessageLoop::AutoRunState::~AutoRunState() {
-  loop_->state_ = previous_state_;
-}
-
-//------------------------------------------------------------------------------
 // MessageLoopForUI
 
 #if defined(OS_WIN)
 void MessageLoopForUI::DidProcessMessage(const MSG& message) {
   pump_win()->DidProcessMessage(message);
 }
 #endif  // defined(OS_WIN)
 
 #if defined(OS_ANDROID)
 void MessageLoopForUI::Start() {
   // No Histogram support for UI message loop as it is managed by Java side
   static_cast<base::MessagePumpForUI*>(pump_.get())->Start(this);
 }
 #endif
 
 #if !defined(OS_MACOSX) && !defined(OS_NACL) && !defined(OS_ANDROID)
 void MessageLoopForUI::AddObserver(Observer* observer) {
   pump_ui()->AddObserver(observer);
 }
 
 void MessageLoopForUI::RemoveObserver(Observer* observer) {
   pump_ui()->RemoveObserver(observer);
 }
 
 void MessageLoopForUI::RunWithDispatcher(Dispatcher* dispatcher) {
-  AutoRunState save_state(this);
-  state_->dispatcher = dispatcher;
-  RunHandler();
+  RunLoop run_loop(dispatcher);
+  run_loop.Run();
 }
 
 void MessageLoopForUI::RunAllPendingWithDispatcher(Dispatcher* dispatcher) {
-  AutoRunState save_state(this);
-  state_->dispatcher = dispatcher;
-  state_->quit_received = true;  // Means run until we would otherwise block.
-  RunHandler();
+  RunLoop run_loop(dispatcher);
+  run_loop.RunUntilIdle();
 }
 
 #endif  //  !defined(OS_MACOSX) && !defined(OS_NACL) && !defined(OS_ANDROID)
 
 //------------------------------------------------------------------------------
 // MessageLoopForIO
 
 #if defined(OS_WIN)
 
 void MessageLoopForIO::RegisterIOHandler(HANDLE file, IOHandler* handler) {
@@ skipping 13 matching lines @@
                                            Watcher *delegate) {
   return pump_libevent()->WatchFileDescriptor(
       fd,
       persistent,
       static_cast<base::MessagePumpLibevent::Mode>(mode),
       controller,
       delegate);
 }
 
 #endif