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/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 Thread::Options::Options()
  40     : message_loop_type(MessageLoop::TYPE_DEFAULT),
  41       timer_slack(TIMER_SLACK_NONE),
  42       stack_size(0),
  43       priority(ThreadPriority::NORMAL) {
  44 }
  45
  46 Thread::Options::Options(MessageLoop::Type type,
  47                          size_t size)
  48     : message_loop_type(type),
  49       timer_slack(TIMER_SLACK_NONE),
  50       stack_size(size),
  51       priority(ThreadPriority::NORMAL) {
  52 }
  53
  54 Thread::Options::~Options() {
  55 }
  56
  57 Thread::Thread(const std::string& name)
  58     :
  59 #if defined(OS_WIN)
  60       com_status_(NONE),
  61 #endif
  62       stopping_(false),
  63       running_(false),
  64       thread_(0),
  65       message_loop_(nullptr),
  66       message_loop_timer_slack_(TIMER_SLACK_NONE),
  67       name_(name) {
  68 }
  69
  70 Thread::~Thread() {
  71   Stop();
  72 }
  73
  74 bool Thread::Start() {
  75   Options options;
  76 #if defined(OS_WIN)
  77   if (com_status_ == STA)
  78     options.message_loop_type = MessageLoop::TYPE_UI;
  79 #endif
  80   return StartWithOptions(options);
  81 }
  82
  83 bool Thread::StartWithOptions(const Options& options) {
  84   DCHECK(!message_loop_);
  85 #if defined(OS_WIN)
  86   DCHECK((com_status_ != STA) ||
  87       (options.message_loop_type == MessageLoop::TYPE_UI));
  88 #endif
  89
  90   SetThreadWasQuitProperly(false);
  91
  92   MessageLoop::Type type = options.message_loop_type;
  93   if (!options.message_pump_factory.is_null())
  94     type = MessageLoop::TYPE_CUSTOM;
  95
  96   message_loop_timer_slack_ = options.timer_slack;
  97   message_loop_ = new MessageLoop(type, options.message_pump_factory);
  98
  99   start_event_.reset(new WaitableEvent(false, false));
 100
 101   // Hold the thread_lock_ while starting a new thread, so that we can make sure
 102   // that thread_ is populated before the newly created thread accesses it.
 103   {
 104     AutoLock lock(thread_lock_);
 105     bool created;
 106     if (options.priority == ThreadPriority::NORMAL) {
 107       created = PlatformThread::Create(options.stack_size, this, &thread_);
 108     } else {
 109       created = PlatformThread::CreateWithPriority(options.stack_size, this,
 110                                                    &thread_, options.priority);
 111     }
 112     if (!created) {
 113       DLOG(ERROR) << "failed to create thread";
 114       delete message_loop_;
 115       message_loop_ = nullptr;
 116       start_event_.reset();
 117       return false;
 118     }
 119   }
 120
 121   DCHECK(message_loop_);
 122   return true;
 123 }
 124
 125 bool Thread::StartAndWaitForTesting() {
 126   bool result = Start();
 127   if (!result)
 128     return false;
 129   WaitUntilThreadStarted();
 130   return true;
 131 }
 132
 133 bool Thread::WaitUntilThreadStarted() {
 134   if (!start_event_)
 135     return false;
 136   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 137   start_event_->Wait();
 138   return true;
 139 }
 140
 141 void Thread::Stop() {
 142   if (!start_event_)
 143     return;
 144
 145   StopSoon();
 146
 147   // Wait for the thread to exit.
 148   //
 149   // TODO(darin): Unfortunately, we need to keep message_loop_ around until
 150   // the thread exits.  Some consumers are abusing the API.  Make them stop.
 151   //
 152   PlatformThread::Join(thread_);
 153
 154   // The thread should NULL message_loop_ on exit.
 155   DCHECK(!message_loop_);
 156
 157   // The thread no longer needs to be joined.
 158   start_event_.reset();
 159
 160   stopping_ = false;
 161 }
 162
 163 void Thread::StopSoon() {
 164   // We should only be called on the same thread that started us.
 165
 166   DCHECK_NE(thread_id(), PlatformThread::CurrentId());
 167
 168   if (stopping_ || !message_loop_)
 169     return;
 170
 171   stopping_ = true;
 172   task_runner()->PostTask(FROM_HERE, base::Bind(&ThreadQuitHelper));
 173 }
 174
 175 PlatformThreadId Thread::thread_id() const {
 176   AutoLock lock(thread_lock_);
 177   return thread_.id();
 178 }
 179
 180 bool Thread::IsRunning() const {
 181   // If the thread's already started (i.e. message_loop_ is non-null) and
 182   // not yet requested to stop (i.e. stopping_ is false) we can just return
 183   // true. (Note that stopping_ is touched only on the same thread that
 184   // starts / started the new thread so we need no locking here.)
 185   if (message_loop_ && !stopping_)
 186     return true;
 187   // Otherwise check the running_ flag, which is set to true by the new thread
 188   // only while it is inside Run().
 189   AutoLock lock(running_lock_);
 190   return running_;
 191 }
 192
 193 void Thread::SetPriority(ThreadPriority priority) {
 194   // The thread must be started (and id known) for this to be
 195   // compatible with all platforms.
 196   DCHECK(message_loop_ != nullptr);
 197   PlatformThread::SetThreadPriority(thread_, priority);
 198 }
 199
 200 void Thread::Run(MessageLoop* message_loop) {
 201   message_loop->Run();
 202 }
 203
 204 void Thread::SetThreadWasQuitProperly(bool flag) {
 205   lazy_tls_bool.Pointer()->Set(flag);
 206 }
 207
 208 bool Thread::GetThreadWasQuitProperly() {
 209   bool quit_properly = true;
 210 #ifndef NDEBUG
 211   quit_properly = lazy_tls_bool.Pointer()->Get();
 212 #endif
 213   return quit_properly;
 214 }
 215
 216 void Thread::ThreadMain() {
 217   // Complete the initialization of our Thread object.
 218   PlatformThread::SetName(name_.c_str());
 219   ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
 220
 221   // Lazily initialize the message_loop so that it can run on this thread.
 222   DCHECK(message_loop_);
 223   scoped_ptr<MessageLoop> message_loop(message_loop_);
 224   message_loop_->BindToCurrentThread();
 225   message_loop_->set_thread_name(name_);
 226   message_loop_->SetTimerSlack(message_loop_timer_slack_);
 227
 228 #if defined(OS_WIN)
 229   scoped_ptr<win::ScopedCOMInitializer> com_initializer;
 230   if (com_status_ != NONE) {
 231     com_initializer.reset((com_status_ == STA) ?
 232         new win::ScopedCOMInitializer() :
 233         new win::ScopedCOMInitializer(win::ScopedCOMInitializer::kMTA));
 234   }
 235 #endif
 236
 237   // Make sure the thread_id() returns current thread.
 238   // (This internally acquires lock against PlatformThread::Create)
 239   DCHECK_EQ(thread_id(), PlatformThread::CurrentId());
 240
 241   // Let the thread do extra initialization.
 242   Init();
 243
 244   {
 245     AutoLock lock(running_lock_);
 246     running_ = true;
 247   }
 248
 249   start_event_->Signal();
 250
 251   Run(message_loop_);
 252
 253   {
 254     AutoLock lock(running_lock_);
 255     running_ = false;
 256   }
 257
 258   // Let the thread do extra cleanup.
 259   CleanUp();
 260
 261 #if defined(OS_WIN)
 262   com_initializer.reset();
 263 #endif
 264
 265   // Assert that MessageLoop::Quit was called by ThreadQuitHelper.
 266   DCHECK(GetThreadWasQuitProperly());
 267
 268   // We can't receive messages anymore.
 269   // (The message loop is destructed at the end of this block)
 270   message_loop_ = NULL;
 271 }
 272
 273 }  // namespace base