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/location.h"
  10 #include "base/profiler/scoped_tracker.h"
  11 #include "base/synchronization/waitable_event.h"
  12 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
  13 #include "base/threading/thread_id_name_manager.h"
  14 #include "base/threading/thread_local.h"
  15 #include "base/threading/thread_restrictions.h"
  16
  17 #if defined(OS_WIN)
  18 #include "base/win/scoped_com_initializer.h"
  19 #endif
  20
  21 namespace base {
  22
  23 namespace {
  24
  25 // We use this thread-local variable to record whether or not a thread exited
  26 // because its Stop method was called.  This allows us to catch cases where
  27 // MessageLoop::QuitWhenIdle() is called directly, which is unexpected when
  28 // using a Thread to setup and run a MessageLoop.
  29 base::LazyInstance<base::ThreadLocalBoolean> lazy_tls_bool =
  30     LAZY_INSTANCE_INITIALIZER;
  31
  32 }  // namespace
  33
  34 // This is used to trigger the message loop to exit.
  35 void ThreadQuitHelper() {
  36   MessageLoop::current()->QuitWhenIdle();
  37   Thread::SetThreadWasQuitProperly(true);
  38 }
  39
  40 Thread::Options::Options()
  41     : message_loop_type(MessageLoop::TYPE_DEFAULT),
  42       timer_slack(TIMER_SLACK_NONE),
  43       stack_size(0),
  44       priority(ThreadPriority::NORMAL) {
  45 }
  46
  47 Thread::Options::Options(MessageLoop::Type type,
  48                          size_t size)
  49     : message_loop_type(type),
  50       timer_slack(TIMER_SLACK_NONE),
  51       stack_size(size),
  52       priority(ThreadPriority::NORMAL) {
  53 }
  54
  55 Thread::Options::~Options() {
  56 }
  57
  58 Thread::Thread(const std::string& name)
  59     :
  60 #if defined(OS_WIN)
  61       com_status_(NONE),
  62 #endif
  63       stopping_(false),
  64       running_(false),
  65       thread_(0),
  66       id_(kInvalidThreadId),
  67       id_event_(true, false),
  68       message_loop_(nullptr),
  69       message_loop_timer_slack_(TIMER_SLACK_NONE),
  70       name_(name) {
  71 }
  72
  73 Thread::~Thread() {
  74   Stop();
  75 }
  76
  77 bool Thread::Start() {
  78   Options options;
  79 #if defined(OS_WIN)
  80   if (com_status_ == STA)
  81     options.message_loop_type = MessageLoop::TYPE_UI;
  82 #endif
  83   return StartWithOptions(options);
  84 }
  85
  86 bool Thread::StartWithOptions(const Options& options) {
  87   DCHECK(!message_loop_);
  88 #if defined(OS_WIN)
  89   DCHECK((com_status_ != STA) ||
  90       (options.message_loop_type == MessageLoop::TYPE_UI));
  91 #endif
  92
  93   // Reset |id_| here to support restarting the thread.
  94   id_event_.Reset();
  95   id_ = kInvalidThreadId;
  96
  97   SetThreadWasQuitProperly(false);
  98
  99   MessageLoop::Type type = options.message_loop_type;
 100   if (!options.message_pump_factory.is_null())
 101     type = MessageLoop::TYPE_CUSTOM;
 102
 103   message_loop_timer_slack_ = options.timer_slack;
 104   scoped_ptr<MessageLoop> message_loop = MessageLoop::CreateUnbound(
 105       type, options.message_pump_factory);
 106   message_loop_ = message_loop.get();
 107   start_event_.reset(new WaitableEvent(false, false));
 108
 109   // Hold the thread_lock_ while starting a new thread, so that we can make sure
 110   // that thread_ is populated before the newly created thread accesses it.
 111   {
 112     AutoLock lock(thread_lock_);
 113     if (!PlatformThread::CreateWithPriority(options.stack_size, this, &thread_,
 114                                             options.priority)) {
 115       DLOG(ERROR) << "failed to create thread";
 116       message_loop_ = nullptr;
 117       start_event_.reset();
 118       return false;
 119     }
 120   }
 121
 122   // The ownership of message_loop is managemed by the newly created thread
 123   // within the ThreadMain.
 124   ignore_result(message_loop.release());
 125
 126   DCHECK(message_loop_);
 127   return true;
 128 }
 129
 130 bool Thread::StartAndWaitForTesting() {
 131   bool result = Start();
 132   if (!result)
 133     return false;
 134   WaitUntilThreadStarted();
 135   return true;
 136 }
 137
 138 bool Thread::WaitUntilThreadStarted() {
 139   if (!start_event_)
 140     return false;
 141   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 142   start_event_->Wait();
 143   return true;
 144 }
 145
 146 void Thread::Stop() {
 147   if (!start_event_)
 148     return;
 149
 150   StopSoon();
 151
 152   // Wait for the thread to exit.
 153   //
 154   // TODO(darin): Unfortunately, we need to keep message_loop_ around until
 155   // the thread exits.  Some consumers are abusing the API.  Make them stop.
 156   //
 157   PlatformThread::Join(thread_);
 158
 159   // The thread should NULL message_loop_ on exit.
 160   DCHECK(!message_loop_);
 161
 162   // The thread no longer needs to be joined.
 163   start_event_.reset();
 164
 165   stopping_ = false;
 166 }
 167
 168 void Thread::StopSoon() {
 169   // We should only be called on the same thread that started us.
 170
 171   DCHECK_NE(GetThreadId(), PlatformThread::CurrentId());
 172
 173   if (stopping_ || !message_loop_)
 174     return;
 175
 176   stopping_ = true;
 177   task_runner()->PostTask(FROM_HERE, base::Bind(&ThreadQuitHelper));
 178 }
 179
 180 PlatformThreadId Thread::GetThreadId() const {
 181   // If the thread is created but not started yet, wait for |id_| being ready.
 182   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 183   // TODO(toyoshim): Remove this after a few days (crbug.com/495097)
 184   tracked_objects::ScopedTracker tracking_profile(
 185       FROM_HERE_WITH_EXPLICIT_FUNCTION(
 186           "495097 base::Thread::GetThreadId"));
 187   id_event_.Wait();
 188   return id_;
 189 }
 190
 191 bool Thread::IsRunning() const {
 192   // If the thread's already started (i.e. message_loop_ is non-null) and
 193   // not yet requested to stop (i.e. stopping_ is false) we can just return
 194   // true. (Note that stopping_ is touched only on the same thread that
 195   // starts / started the new thread so we need no locking here.)
 196   if (message_loop_ && !stopping_)
 197     return true;
 198   // Otherwise check the running_ flag, which is set to true by the new thread
 199   // only while it is inside Run().
 200   AutoLock lock(running_lock_);
 201   return running_;
 202 }
 203
 204 void Thread::Run(MessageLoop* message_loop) {
 205   message_loop->Run();
 206 }
 207
 208 void Thread::SetThreadWasQuitProperly(bool flag) {
 209   lazy_tls_bool.Pointer()->Set(flag);
 210 }
 211
 212 bool Thread::GetThreadWasQuitProperly() {
 213   bool quit_properly = true;
 214 #ifndef NDEBUG
 215   quit_properly = lazy_tls_bool.Pointer()->Get();
 216 #endif
 217   return quit_properly;
 218 }
 219
 220 void Thread::ThreadMain() {
 221   // First, make GetThreadId() available to avoid deadlocks. It could be called
 222   // any place in the following thread initialization code.
 223   id_ = PlatformThread::CurrentId();
 224   DCHECK_NE(kInvalidThreadId, id_);
 225   id_event_.Signal();
 226
 227   // Complete the initialization of our Thread object.
 228   PlatformThread::SetName(name_.c_str());
 229   ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
 230
 231   // Lazily initialize the message_loop so that it can run on this thread.
 232   DCHECK(message_loop_);
 233   scoped_ptr<MessageLoop> message_loop(message_loop_);
 234   message_loop_->BindToCurrentThread();
 235   message_loop_->set_thread_name(name_);
 236   message_loop_->SetTimerSlack(message_loop_timer_slack_);
 237
 238 #if defined(OS_WIN)
 239   scoped_ptr<win::ScopedCOMInitializer> com_initializer;
 240   if (com_status_ != NONE) {
 241     com_initializer.reset((com_status_ == STA) ?
 242         new win::ScopedCOMInitializer() :
 243         new win::ScopedCOMInitializer(win::ScopedCOMInitializer::kMTA));
 244   }
 245 #endif
 246
 247   // Let the thread do extra initialization.
 248   Init();
 249
 250   {
 251     AutoLock lock(running_lock_);
 252     running_ = true;
 253   }
 254
 255   start_event_->Signal();
 256
 257   Run(message_loop_);
 258
 259   {
 260     AutoLock lock(running_lock_);
 261     running_ = false;
 262   }
 263
 264   // Let the thread do extra cleanup.
 265   CleanUp();
 266
 267 #if defined(OS_WIN)
 268   com_initializer.reset();
 269 #endif
 270
 271   // Assert that MessageLoop::Quit was called by ThreadQuitHelper.
 272   DCHECK(GetThreadWasQuitProperly());
 273
 274   // We can't receive messages anymore.
 275   // (The message loop is destructed at the end of this block)
 276   message_loop_ = NULL;
 277 }
 278
 279 }  // namespace base