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       id_(kInvalidThreadId),
  66       id_event_(true, false),
  67       message_loop_(nullptr),
  68       message_loop_timer_slack_(TIMER_SLACK_NONE),
  69       name_(name),
  70       start_event_(false, false) {
  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();
 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       return false;
 118     }
 119   }
 120
 121   // The ownership of message_loop is managemed by the newly created thread
 122   // within the ThreadMain.
 123   ignore_result(message_loop.release());
 124
 125   DCHECK(message_loop_);
 126   return true;
 127 }
 128
 129 bool Thread::StartAndWaitForTesting() {
 130   bool result = Start();
 131   if (!result)
 132     return false;
 133   WaitUntilThreadStarted();
 134   return true;
 135 }
 136
 137 bool Thread::WaitUntilThreadStarted() const {
 138   if (!message_loop_)
 139     return false;
 140   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 141   start_event_.Wait();
 142   return true;
 143 }
 144
 145 void Thread::Stop() {
 146   AutoLock lock(thread_lock_);
 147   if (thread_.is_null())
 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   thread_ = base::PlatformThreadHandle();
 159
 160   // The thread should nullify message_loop_ on exit.
 161   DCHECK(!message_loop_);
 162
 163   stopping_ = false;
 164 }
 165
 166 void Thread::StopSoon() {
 167   // We should only be called on the same thread that started us.
 168
 169   DCHECK_NE(GetThreadId(), PlatformThread::CurrentId());
 170
 171   if (stopping_ || !message_loop_)
 172     return;
 173
 174   stopping_ = true;
 175   task_runner()->PostTask(FROM_HERE, base::Bind(&ThreadQuitHelper));
 176 }
 177
 178 PlatformThreadId Thread::GetThreadId() const {
 179   // If the thread is created but not started yet, wait for |id_| being ready.
 180   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 181   id_event_.Wait();
 182   return id_;
 183 }
 184
 185 bool Thread::IsRunning() const {
 186   // If the thread's already started (i.e. message_loop_ is non-null) and
 187   // not yet requested to stop (i.e. stopping_ is false) we can just return
 188   // true. (Note that stopping_ is touched only on the same thread that
 189   // starts / started the new thread so we need no locking here.)
 190   if (message_loop_ && !stopping_)
 191     return true;
 192   // Otherwise check the running_ flag, which is set to true by the new thread
 193   // only while it is inside Run().
 194   AutoLock lock(running_lock_);
 195   return running_;
 196 }
 197
 198 void Thread::Run(MessageLoop* message_loop) {
 199   message_loop->Run();
 200 }
 201
 202 void Thread::SetThreadWasQuitProperly(bool flag) {
 203   lazy_tls_bool.Pointer()->Set(flag);
 204 }
 205
 206 bool Thread::GetThreadWasQuitProperly() {
 207   bool quit_properly = true;
 208 #ifndef NDEBUG
 209   quit_properly = lazy_tls_bool.Pointer()->Get();
 210 #endif
 211   return quit_properly;
 212 }
 213
 214 void Thread::ThreadMain() {
 215   // First, make GetThreadId() available to avoid deadlocks. It could be called
 216   // any place in the following thread initialization code.
 217   id_ = PlatformThread::CurrentId();
 218   DCHECK_NE(kInvalidThreadId, id_);
 219   id_event_.Signal();
 220
 221   // Complete the initialization of our Thread object.
 222   PlatformThread::SetName(name_.c_str());
 223   ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
 224
 225   // Lazily initialize the message_loop so that it can run on this thread.
 226   DCHECK(message_loop_);
 227   scoped_ptr<MessageLoop> message_loop(message_loop_);
 228   message_loop_->BindToCurrentThread();
 229   message_loop_->set_thread_name(name_);
 230   message_loop_->SetTimerSlack(message_loop_timer_slack_);
 231
 232 #if defined(OS_WIN)
 233   scoped_ptr<win::ScopedCOMInitializer> com_initializer;
 234   if (com_status_ != NONE) {
 235     com_initializer.reset((com_status_ == STA) ?
 236         new win::ScopedCOMInitializer() :
 237         new win::ScopedCOMInitializer(win::ScopedCOMInitializer::kMTA));
 238   }
 239 #endif
 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_ = nullptr;
 271 }
 272
 273 }  // namespace base