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     bool created;
 107     if (options.priority == ThreadPriority::NORMAL) {
 108       created = PlatformThread::Create(options.stack_size, this, &thread_);
 109     } else {
 110       created = PlatformThread::CreateWithPriority(options.stack_size, this,
 111                                                    &thread_, options.priority);
 112     }
 113     if (!created) {
 114       DLOG(ERROR) << "failed to create thread";
 115       message_loop_ = nullptr;
 116       start_event_.reset();
 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() {
 138   if (!start_event_)
 139     return false;
 140   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 141   start_event_->Wait();
 142   return true;
 143 }
 144
 145 void Thread::Stop() {
 146   if (!start_event_)
 147     return;
 148
 149   StopSoon();
 150
 151   // Wait for the thread to exit.
 152   //
 153   // TODO(darin): Unfortunately, we need to keep message_loop_ around until
 154   // the thread exits.  Some consumers are abusing the API.  Make them stop.
 155   //
 156   PlatformThread::Join(thread_);
 157
 158   // The thread should NULL message_loop_ on exit.
 159   DCHECK(!message_loop_);
 160
 161   // The thread no longer needs to be joined.
 162   start_event_.reset();
 163
 164   stopping_ = false;
 165 }
 166
 167 void Thread::StopSoon() {
 168   // We should only be called on the same thread that started us.
 169
 170   DCHECK_NE(thread_id(), PlatformThread::CurrentId());
 171
 172   if (stopping_ || !message_loop_)
 173     return;
 174
 175   stopping_ = true;
 176   task_runner()->PostTask(FROM_HERE, base::Bind(&ThreadQuitHelper));
 177 }
 178
 179 PlatformThreadId Thread::thread_id() const {
 180   AutoLock lock(thread_lock_);
 181   return thread_.id();
 182 }
 183
 184 bool Thread::IsRunning() const {
 185   // If the thread's already started (i.e. message_loop_ is non-null) and
 186   // not yet requested to stop (i.e. stopping_ is false) we can just return
 187   // true. (Note that stopping_ is touched only on the same thread that
 188   // starts / started the new thread so we need no locking here.)
 189   if (message_loop_ && !stopping_)
 190     return true;
 191   // Otherwise check the running_ flag, which is set to true by the new thread
 192   // only while it is inside Run().
 193   AutoLock lock(running_lock_);
 194   return running_;
 195 }
 196
 197 void Thread::Run(MessageLoop* message_loop) {
 198   message_loop->Run();
 199 }
 200
 201 void Thread::SetThreadWasQuitProperly(bool flag) {
 202   lazy_tls_bool.Pointer()->Set(flag);
 203 }
 204
 205 bool Thread::GetThreadWasQuitProperly() {
 206   bool quit_properly = true;
 207 #ifndef NDEBUG
 208   quit_properly = lazy_tls_bool.Pointer()->Get();
 209 #endif
 210   return quit_properly;
 211 }
 212
 213 void Thread::ThreadMain() {
 214   // Complete the initialization of our Thread object.
 215   PlatformThread::SetName(name_.c_str());
 216   ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
 217
 218   // Lazily initialize the message_loop so that it can run on this thread.
 219   DCHECK(message_loop_);
 220   scoped_ptr<MessageLoop> message_loop(message_loop_);
 221   message_loop_->BindToCurrentThread();
 222   message_loop_->set_thread_name(name_);
 223   message_loop_->SetTimerSlack(message_loop_timer_slack_);
 224
 225 #if defined(OS_WIN)
 226   scoped_ptr<win::ScopedCOMInitializer> com_initializer;
 227   if (com_status_ != NONE) {
 228     com_initializer.reset((com_status_ == STA) ?
 229         new win::ScopedCOMInitializer() :
 230         new win::ScopedCOMInitializer(win::ScopedCOMInitializer::kMTA));
 231   }
 232 #endif
 233
 234   // Make sure the thread_id() returns current thread.
 235   // (This internally acquires lock against PlatformThread::Create)
 236   DCHECK_EQ(thread_id(), PlatformThread::CurrentId());
 237
 238   // Let the thread do extra initialization.
 239   Init();
 240
 241   {
 242     AutoLock lock(running_lock_);
 243     running_ = true;
 244   }
 245
 246   start_event_->Signal();
 247
 248   Run(message_loop_);
 249
 250   {
 251     AutoLock lock(running_lock_);
 252     running_ = false;
 253   }
 254
 255   // Let the thread do extra cleanup.
 256   CleanUp();
 257
 258 #if defined(OS_WIN)
 259   com_initializer.reset();
 260 #endif
 261
 262   // Assert that MessageLoop::Quit was called by ThreadQuitHelper.
 263   DCHECK(GetThreadWasQuitProperly());
 264
 265   // We can't receive messages anymore.
 266   // (The message loop is destructed at the end of this block)
 267   message_loop_ = NULL;
 268 }
 269
 270 }  // namespace base