base/threading/thread.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/threading/thread.h"
   6
   7 #include "base/bind.h"
   8 #include "base/lazy_instance.h"
   9 #include "base/profiler/scoped_tracker.h"
  10 #include "base/synchronization/waitable_event.h"
  11 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
  12 #include "base/threading/thread_id_name_manager.h"
  13 #include "base/threading/thread_local.h"
  14 #include "base/threading/thread_restrictions.h"
  15
  16 #if defined(OS_WIN)
  17 #include "base/win/scoped_com_initializer.h"
  18 #endif
  19
  20 namespace base {
  21
  22 namespace {
  23
  24 // We use this thread-local variable to record whether or not a thread exited
  25 // because its Stop method was called.  This allows us to catch cases where
  26 // MessageLoop::QuitWhenIdle() is called directly, which is unexpected when
  27 // using a Thread to setup and run a MessageLoop.
  28 base::LazyInstance<base::ThreadLocalBoolean> lazy_tls_bool =
  29     LAZY_INSTANCE_INITIALIZER;
  30
  31 }  // namespace
  32
  33 // This is used to trigger the message loop to exit.
  34 void ThreadQuitHelper() {
  35   MessageLoop::current()->QuitWhenIdle();
  36   Thread::SetThreadWasQuitProperly(true);
  37 }
  38
  39 // Used to pass data to ThreadMain.  This structure is allocated on the stack
  40 // from within StartWithOptions.
  41 struct Thread::StartupData {
  42   // We get away with a const reference here because of how we are allocated.
  43   const Thread::Options& options;
  44
  45   // Used to synchronize thread startup.
  46   WaitableEvent event;
  47
  48   explicit StartupData(const Options& opt)
  49       : options(opt),
  50         event(false, false) {}
  51 };
  52
  53 Thread::Options::Options()
  54     : message_loop_type(MessageLoop::TYPE_DEFAULT),
  55       timer_slack(TIMER_SLACK_NONE),
  56       stack_size(0) {
  57 }
  58
  59 Thread::Options::Options(MessageLoop::Type type,
  60                          size_t size)
  61     : message_loop_type(type),
  62       timer_slack(TIMER_SLACK_NONE),
  63       stack_size(size) {
  64 }
  65
  66 Thread::Options::~Options() {
  67 }
  68
  69 Thread::Thread(const std::string& name)
  70     :
  71 #if defined(OS_WIN)
  72       com_status_(NONE),
  73 #endif
  74       started_(false),
  75       stopping_(false),
  76       running_(false),
  77       startup_data_(NULL),
  78       thread_(0),
  79       message_loop_(NULL),
  80       thread_id_(kInvalidThreadId),
  81       name_(name) {
  82 }
  83
  84 Thread::~Thread() {
  85   Stop();
  86 }
  87
  88 bool Thread::Start() {
  89   Options options;
  90 #if defined(OS_WIN)
  91   if (com_status_ == STA)
  92     options.message_loop_type = MessageLoop::TYPE_UI;
  93 #endif
  94   return StartWithOptions(options);
  95 }
  96
  97 bool Thread::StartWithOptions(const Options& options) {
  98   DCHECK(!message_loop_);
  99 #if defined(OS_WIN)
 100   DCHECK((com_status_ != STA) ||
 101       (options.message_loop_type == MessageLoop::TYPE_UI));
 102 #endif
 103
 104   SetThreadWasQuitProperly(false);
 105
 106   StartupData startup_data(options);
 107   startup_data_ = &startup_data;
 108
 109   if (!PlatformThread::Create(options.stack_size, this, &thread_)) {
 110     DLOG(ERROR) << "failed to create thread";
 111     startup_data_ = NULL;
 112     return false;
 113   }
 114
 115   // TODO(kinuko): Remove once crbug.com/465458 is solved.
 116   tracked_objects::ScopedTracker tracking_profile_wait(
 117       FROM_HERE_WITH_EXPLICIT_FUNCTION(
 118           "465458 base::Thread::StartWithOptions (Wait)"));
 119
 120   // Wait for the thread to start and initialize message_loop_
 121   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 122   startup_data.event.Wait();
 123
 124   // set it to NULL so we don't keep a pointer to some object on the stack.
 125   startup_data_ = NULL;
 126   started_ = true;
 127
 128   DCHECK(message_loop_);
 129   return true;
 130 }
 131
 132 void Thread::Stop() {
 133   if (!started_)
 134     return;
 135
 136   StopSoon();
 137
 138   // Wait for the thread to exit.
 139   //
 140   // TODO(darin): Unfortunately, we need to keep message_loop_ around until
 141   // the thread exits.  Some consumers are abusing the API.  Make them stop.
 142   //
 143   PlatformThread::Join(thread_);
 144
 145   // The thread should NULL message_loop_ on exit.
 146   DCHECK(!message_loop_);
 147
 148   // The thread no longer needs to be joined.
 149   started_ = false;
 150
 151   stopping_ = false;
 152 }
 153
 154 void Thread::StopSoon() {
 155   // We should only be called on the same thread that started us.
 156
 157   // Reading thread_id_ without a lock can lead to a benign data race
 158   // with ThreadMain, so we annotate it to stay silent under ThreadSanitizer.
 159   DCHECK_NE(ANNOTATE_UNPROTECTED_READ(thread_id_), PlatformThread::CurrentId());
 160
 161   if (stopping_ || !message_loop_)
 162     return;
 163
 164   stopping_ = true;
 165   message_loop_->PostTask(FROM_HERE, base::Bind(&ThreadQuitHelper));
 166 }
 167
 168 bool Thread::IsRunning() const {
 169   return running_;
 170 }
 171
 172 void Thread::SetPriority(ThreadPriority priority) {
 173   // The thread must be started (and id known) for this to be
 174   // compatible with all platforms.
 175   DCHECK_NE(thread_id_, kInvalidThreadId);
 176   PlatformThread::SetThreadPriority(thread_, priority);
 177 }
 178
 179 void Thread::Run(MessageLoop* message_loop) {
 180   message_loop->Run();
 181 }
 182
 183 void Thread::SetThreadWasQuitProperly(bool flag) {
 184   lazy_tls_bool.Pointer()->Set(flag);
 185 }
 186
 187 bool Thread::GetThreadWasQuitProperly() {
 188   bool quit_properly = true;
 189 #ifndef NDEBUG
 190   quit_properly = lazy_tls_bool.Pointer()->Get();
 191 #endif
 192   return quit_properly;
 193 }
 194
 195 void Thread::ThreadMain() {
 196   {
 197     // The message loop for this thread.
 198     // Allocated on the heap to centralize any leak reports at this line.
 199     scoped_ptr<MessageLoop> message_loop;
 200     if (!startup_data_->options.message_pump_factory.is_null()) {
 201       message_loop.reset(
 202           new MessageLoop(startup_data_->options.message_pump_factory.Run()));
 203     } else {
 204       message_loop.reset(
 205           new MessageLoop(startup_data_->options.message_loop_type));
 206     }
 207
 208     // Complete the initialization of our Thread object.
 209     thread_id_ = PlatformThread::CurrentId();
 210     PlatformThread::SetName(name_.c_str());
 211     ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
 212     message_loop->set_thread_name(name_);
 213     message_loop->SetTimerSlack(startup_data_->options.timer_slack);
 214     message_loop_ = message_loop.get();
 215
 216 #if defined(OS_WIN)
 217     scoped_ptr<win::ScopedCOMInitializer> com_initializer;
 218     if (com_status_ != NONE) {
 219       com_initializer.reset((com_status_ == STA) ?
 220           new win::ScopedCOMInitializer() :
 221           new win::ScopedCOMInitializer(win::ScopedCOMInitializer::kMTA));
 222     }
 223 #endif
 224
 225     // Let the thread do extra initialization.
 226     // Let's do this before signaling we are started.
 227     Init();
 228
 229     running_ = true;
 230     startup_data_->event.Signal();
 231     // startup_data_ can't be touched anymore since the starting thread is now
 232     // unlocked.
 233
 234     Run(message_loop_);
 235     running_ = false;
 236
 237     // Let the thread do extra cleanup.
 238     CleanUp();
 239
 240 #if defined(OS_WIN)
 241     com_initializer.reset();
 242 #endif
 243
 244     // Assert that MessageLoop::Quit was called by ThreadQuitHelper.
 245     DCHECK(GetThreadWasQuitProperly());
 246
 247     // We can't receive messages anymore.
 248     message_loop_ = NULL;
 249   }
 250 }
 251
 252 }  // namespace base