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   scoped_ptr<MessageLoop> message_loop = MessageLoop::CreateUnbound(
  98       type, options.message_pump_factory);
  99   message_loop_ = message_loop.get();
 100   start_event_.reset(new WaitableEvent(false, false));
 101
 102   // Hold the thread_lock_ while starting a new thread, so that we can make sure
 103   // that thread_ is populated before the newly created thread accesses it.
 104   {
 105     AutoLock lock(thread_lock_);
 106     if (!PlatformThread::CreateWithPriority(options.stack_size, this, &thread_,
 107                                             options.priority)) {
 108       DLOG(ERROR) << "failed to create thread";
 109       message_loop_ = nullptr;
 110       start_event_.reset();
 111       return false;
 112     }
 113   }
 114
 115   // The ownership of message_loop is managemed by the newly created thread
 116   // within the ThreadMain.
 117   ignore_result(message_loop.release());
 118
 119   DCHECK(message_loop_);
 120   return true;
 121 }
 122
 123 bool Thread::StartAndWaitForTesting() {
 124   bool result = Start();
 125   if (!result)
 126     return false;
 127   WaitUntilThreadStarted();
 128   return true;
 129 }
 130
 131 bool Thread::WaitUntilThreadStarted() {
 132   if (!start_event_)
 133     return false;
 134   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 135   start_event_->Wait();
 136   return true;
 137 }
 138
 139 void Thread::Stop() {
 140   if (!start_event_)
 141     return;
 142
 143   StopSoon();
 144
 145   // Wait for the thread to exit.
 146   //
 147   // TODO(darin): Unfortunately, we need to keep message_loop_ around until
 148   // the thread exits.  Some consumers are abusing the API.  Make them stop.
 149   //
 150   PlatformThread::Join(thread_);
 151
 152   // The thread should NULL message_loop_ on exit.
 153   DCHECK(!message_loop_);
 154
 155   // The thread no longer needs to be joined.
 156   start_event_.reset();
 157
 158   stopping_ = false;
 159 }
 160
 161 void Thread::StopSoon() {
 162   // We should only be called on the same thread that started us.
 163
 164   DCHECK_NE(thread_id(), PlatformThread::CurrentId());
 165
 166   if (stopping_ || !message_loop_)
 167     return;
 168
 169   stopping_ = true;
 170   task_runner()->PostTask(FROM_HERE, base::Bind(&ThreadQuitHelper));
 171 }
 172
 173 PlatformThreadId Thread::thread_id() const {
 174   AutoLock lock(thread_lock_);
 175   return thread_.id();
 176 }
 177
 178 bool Thread::IsRunning() const {
 179   // If the thread's already started (i.e. message_loop_ is non-null) and
 180   // not yet requested to stop (i.e. stopping_ is false) we can just return
 181   // true. (Note that stopping_ is touched only on the same thread that
 182   // starts / started the new thread so we need no locking here.)
 183   if (message_loop_ && !stopping_)
 184     return true;
 185   // Otherwise check the running_ flag, which is set to true by the new thread
 186   // only while it is inside Run().
 187   AutoLock lock(running_lock_);
 188   return running_;
 189 }
 190
 191 void Thread::Run(MessageLoop* message_loop) {
 192   message_loop->Run();
 193 }
 194
 195 void Thread::SetThreadWasQuitProperly(bool flag) {
 196   lazy_tls_bool.Pointer()->Set(flag);
 197 }
 198
 199 bool Thread::GetThreadWasQuitProperly() {
 200   bool quit_properly = true;
 201 #ifndef NDEBUG
 202   quit_properly = lazy_tls_bool.Pointer()->Get();
 203 #endif
 204   return quit_properly;
 205 }
 206
 207 void Thread::ThreadMain() {
 208   // Complete the initialization of our Thread object.
 209   PlatformThread::SetName(name_.c_str());
 210   ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
 211
 212   // Lazily initialize the message_loop so that it can run on this thread.
 213   DCHECK(message_loop_);
 214   scoped_ptr<MessageLoop> message_loop(message_loop_);
 215   message_loop_->BindToCurrentThread();
 216   message_loop_->set_thread_name(name_);
 217   message_loop_->SetTimerSlack(message_loop_timer_slack_);
 218
 219 #if defined(OS_WIN)
 220   scoped_ptr<win::ScopedCOMInitializer> com_initializer;
 221   if (com_status_ != NONE) {
 222     com_initializer.reset((com_status_ == STA) ?
 223         new win::ScopedCOMInitializer() :
 224         new win::ScopedCOMInitializer(win::ScopedCOMInitializer::kMTA));
 225   }
 226 #endif
 227
 228   // Make sure the thread_id() returns current thread.
 229   // (This internally acquires lock against PlatformThread::Create)
 230   DCHECK_EQ(thread_id(), PlatformThread::CurrentId());
 231
 232   // Let the thread do extra initialization.
 233   Init();
 234
 235   {
 236     AutoLock lock(running_lock_);
 237     running_ = true;
 238   }
 239
 240   start_event_->Signal();
 241
 242   Run(message_loop_);
 243
 244   {
 245     AutoLock lock(running_lock_);
 246     running_ = false;
 247   }
 248
 249   // Let the thread do extra cleanup.
 250   CleanUp();
 251
 252 #if defined(OS_WIN)
 253   com_initializer.reset();
 254 #endif
 255
 256   // Assert that MessageLoop::Quit was called by ThreadQuitHelper.
 257   DCHECK(GetThreadWasQuitProperly());
 258
 259   // We can't receive messages anymore.
 260   // (The message loop is destructed at the end of this block)
 261   message_loop_ = NULL;
 262 }
 263
 264 }  // namespace base