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   // TODO(eroman): Remove once crbug.com/465458 is solved.
  99   tracked_objects::ScopedTracker tracking_profile(
 100       FROM_HERE_WITH_EXPLICIT_FUNCTION(
 101         "465458 base::Thread::StartWithOptions"));
 102
 103   DCHECK(!message_loop_);
 104 #if defined(OS_WIN)
 105   DCHECK((com_status_ != STA) ||
 106       (options.message_loop_type == MessageLoop::TYPE_UI));
 107 #endif
 108
 109   SetThreadWasQuitProperly(false);
 110
 111   StartupData startup_data(options);
 112   startup_data_ = &startup_data;
 113
 114   if (!PlatformThread::Create(options.stack_size, this, &thread_)) {
 115     DLOG(ERROR) << "failed to create thread";
 116     startup_data_ = NULL;
 117     return false;
 118   }
 119
 120   // TODO(eroman): Remove once crbug.com/465458 is solved.
 121   tracked_objects::ScopedTracker tracking_profile_wait(
 122       FROM_HERE_WITH_EXPLICIT_FUNCTION(
 123           "465458 base::Thread::StartWithOptions (Wait)"));
 124
 125   // Wait for the thread to start and initialize message_loop_
 126   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 127   startup_data.event.Wait();
 128
 129   // set it to NULL so we don't keep a pointer to some object on the stack.
 130   startup_data_ = NULL;
 131   started_ = true;
 132
 133   DCHECK(message_loop_);
 134   return true;
 135 }
 136
 137 void Thread::Stop() {
 138   if (!started_)
 139     return;
 140
 141   StopSoon();
 142
 143   // Wait for the thread to exit.
 144   //
 145   // TODO(darin): Unfortunately, we need to keep message_loop_ around until
 146   // the thread exits.  Some consumers are abusing the API.  Make them stop.
 147   //
 148   PlatformThread::Join(thread_);
 149
 150   // The thread should NULL message_loop_ on exit.
 151   DCHECK(!message_loop_);
 152
 153   // The thread no longer needs to be joined.
 154   started_ = false;
 155
 156   stopping_ = false;
 157 }
 158
 159 void Thread::StopSoon() {
 160   // We should only be called on the same thread that started us.
 161
 162   // Reading thread_id_ without a lock can lead to a benign data race
 163   // with ThreadMain, so we annotate it to stay silent under ThreadSanitizer.
 164   DCHECK_NE(ANNOTATE_UNPROTECTED_READ(thread_id_), PlatformThread::CurrentId());
 165
 166   if (stopping_ || !message_loop_)
 167     return;
 168
 169   stopping_ = true;
 170   message_loop_->PostTask(FROM_HERE, base::Bind(&ThreadQuitHelper));
 171 }
 172
 173 bool Thread::IsRunning() const {
 174   return running_;
 175 }
 176
 177 void Thread::SetPriority(ThreadPriority priority) {
 178   // The thread must be started (and id known) for this to be
 179   // compatible with all platforms.
 180   DCHECK_NE(thread_id_, kInvalidThreadId);
 181   PlatformThread::SetThreadPriority(thread_, priority);
 182 }
 183
 184 void Thread::Run(MessageLoop* message_loop) {
 185   message_loop->Run();
 186 }
 187
 188 void Thread::SetThreadWasQuitProperly(bool flag) {
 189   lazy_tls_bool.Pointer()->Set(flag);
 190 }
 191
 192 bool Thread::GetThreadWasQuitProperly() {
 193   bool quit_properly = true;
 194 #ifndef NDEBUG
 195   quit_properly = lazy_tls_bool.Pointer()->Get();
 196 #endif
 197   return quit_properly;
 198 }
 199
 200 void Thread::ThreadMain() {
 201   {
 202     // The message loop for this thread.
 203     // Allocated on the heap to centralize any leak reports at this line.
 204     scoped_ptr<MessageLoop> message_loop;
 205     if (!startup_data_->options.message_pump_factory.is_null()) {
 206       message_loop.reset(
 207           new MessageLoop(startup_data_->options.message_pump_factory.Run()));
 208     } else {
 209       message_loop.reset(
 210           new MessageLoop(startup_data_->options.message_loop_type));
 211     }
 212
 213     // Complete the initialization of our Thread object.
 214     thread_id_ = PlatformThread::CurrentId();
 215     PlatformThread::SetName(name_.c_str());
 216     ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
 217     message_loop->set_thread_name(name_);
 218     message_loop->SetTimerSlack(startup_data_->options.timer_slack);
 219     message_loop_ = message_loop.get();
 220
 221 #if defined(OS_WIN)
 222     scoped_ptr<win::ScopedCOMInitializer> com_initializer;
 223     if (com_status_ != NONE) {
 224       com_initializer.reset((com_status_ == STA) ?
 225           new win::ScopedCOMInitializer() :
 226           new win::ScopedCOMInitializer(win::ScopedCOMInitializer::kMTA));
 227     }
 228 #endif
 229
 230     // Let the thread do extra initialization.
 231     // Let's do this before signaling we are started.
 232     Init();
 233
 234     running_ = true;
 235     startup_data_->event.Signal();
 236     // startup_data_ can't be touched anymore since the starting thread is now
 237     // unlocked.
 238
 239     Run(message_loop_);
 240     running_ = false;
 241
 242     // Let the thread do extra cleanup.
 243     CleanUp();
 244
 245 #if defined(OS_WIN)
 246     com_initializer.reset();
 247 #endif
 248
 249     // Assert that MessageLoop::Quit was called by ThreadQuitHelper.
 250     DCHECK(GetThreadWasQuitProperly());
 251
 252     // We can't receive messages anymore.
 253     message_loop_ = NULL;
 254   }
 255 }
 256
 257 }  // namespace base