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/third_party/dynamic_annotations/dynamic_annotations.h"
  10 #include "base/threading/thread_id_name_manager.h"
  11 #include "base/threading/thread_local.h"
  12 #include "base/threading/thread_restrictions.h"
  13 #include "base/synchronization/waitable_event.h"
  14
  15 #if defined(OS_WIN)
  16 #include "base/win/scoped_com_initializer.h"
  17 #endif
  18
  19 namespace base {
  20
  21 namespace {
  22
  23 // We use this thread-local variable to record whether or not a thread exited
  24 // because its Stop method was called.  This allows us to catch cases where
  25 // MessageLoop::QuitWhenIdle() is called directly, which is unexpected when
  26 // using a Thread to setup and run a MessageLoop.
  27 base::LazyInstance<base::ThreadLocalBoolean> lazy_tls_bool =
  28     LAZY_INSTANCE_INITIALIZER;
  29
  30 }  // namespace
  31
  32 // This is used to trigger the message loop to exit.
  33 void ThreadQuitHelper() {
  34   MessageLoop::current()->QuitWhenIdle();
  35   Thread::SetThreadWasQuitProperly(true);
  36 }
  37
  38 // Used to pass data to ThreadMain.  This structure is allocated on the stack
  39 // from within StartWithOptions.
  40 struct Thread::StartupData {
  41   // We get away with a const reference here because of how we are allocated.
  42   const Thread::Options& options;
  43
  44   // Used to synchronize thread startup.
  45   WaitableEvent event;
  46
  47   explicit StartupData(const Options& opt)
  48       : options(opt),
  49         event(false, false) {}
  50 };
  51
  52 Thread::Options::Options()
  53     : message_loop_type(MessageLoop::TYPE_DEFAULT),
  54       timer_slack(TIMER_SLACK_NONE),
  55       stack_size(0) {
  56 }
  57
  58 Thread::Options::Options(MessageLoop::Type type,
  59                          size_t size)
  60     : message_loop_type(type),
  61       timer_slack(TIMER_SLACK_NONE),
  62       stack_size(size) {
  63 }
  64
  65 Thread::Options::~Options() {
  66 }
  67
  68 Thread::Thread(const std::string& name)
  69     :
  70 #if defined(OS_WIN)
  71       com_status_(NONE),
  72 #endif
  73       started_(false),
  74       stopping_(false),
  75       running_(false),
  76       startup_data_(NULL),
  77       thread_(0),
  78       message_loop_(NULL),
  79       thread_id_(kInvalidThreadId),
  80       name_(name) {
  81 }
  82
  83 Thread::~Thread() {
  84   Stop();
  85 }
  86
  87 bool Thread::Start() {
  88   Options options;
  89 #if defined(OS_WIN)
  90   if (com_status_ == STA)
  91     options.message_loop_type = MessageLoop::TYPE_UI;
  92 #endif
  93   return StartWithOptions(options);
  94 }
  95
  96 bool Thread::StartWithOptions(const Options& options) {
  97   DCHECK(!message_loop_);
  98 #if defined(OS_WIN)
  99   DCHECK((com_status_ != STA) ||
 100       (options.message_loop_type == MessageLoop::TYPE_UI));
 101 #endif
 102
 103   SetThreadWasQuitProperly(false);
 104
 105   StartupData startup_data(options);
 106   startup_data_ = &startup_data;
 107
 108   if (!PlatformThread::Create(options.stack_size, this, &thread_)) {
 109     DLOG(ERROR) << "failed to create thread";
 110     startup_data_ = NULL;
 111     return false;
 112   }
 113
 114   // Wait for the thread to start and initialize message_loop_
 115   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 116   startup_data.event.Wait();
 117
 118   // set it to NULL so we don't keep a pointer to some object on the stack.
 119   startup_data_ = NULL;
 120   started_ = true;
 121
 122   DCHECK(message_loop_);
 123   return true;
 124 }
 125
 126 void Thread::Stop() {
 127   if (!started_)
 128     return;
 129
 130   StopSoon();
 131
 132   // Wait for the thread to exit.
 133   //
 134   // TODO(darin): Unfortunately, we need to keep message_loop_ around until
 135   // the thread exits.  Some consumers are abusing the API.  Make them stop.
 136   //
 137   PlatformThread::Join(thread_);
 138
 139   // The thread should NULL message_loop_ on exit.
 140   DCHECK(!message_loop_);
 141
 142   // The thread no longer needs to be joined.
 143   started_ = false;
 144
 145   stopping_ = false;
 146 }
 147
 148 void Thread::StopSoon() {
 149   // We should only be called on the same thread that started us.
 150
 151   // Reading thread_id_ without a lock can lead to a benign data race
 152   // with ThreadMain, so we annotate it to stay silent under ThreadSanitizer.
 153   DCHECK_NE(ANNOTATE_UNPROTECTED_READ(thread_id_), PlatformThread::CurrentId());
 154
 155   if (stopping_ || !message_loop_)
 156     return;
 157
 158   stopping_ = true;
 159   message_loop_->PostTask(FROM_HERE, base::Bind(&ThreadQuitHelper));
 160 }
 161
 162 bool Thread::IsRunning() const {
 163   return running_;
 164 }
 165
 166 void Thread::SetPriority(ThreadPriority priority) {
 167   // The thread must be started (and id known) for this to be
 168   // compatible with all platforms.
 169   DCHECK_NE(thread_id_, kInvalidThreadId);
 170   PlatformThread::SetThreadPriority(thread_, priority);
 171 }
 172
 173 void Thread::Run(MessageLoop* message_loop) {
 174   message_loop->Run();
 175 }
 176
 177 void Thread::SetThreadWasQuitProperly(bool flag) {
 178   lazy_tls_bool.Pointer()->Set(flag);
 179 }
 180
 181 bool Thread::GetThreadWasQuitProperly() {
 182   bool quit_properly = true;
 183 #ifndef NDEBUG
 184   quit_properly = lazy_tls_bool.Pointer()->Get();
 185 #endif
 186   return quit_properly;
 187 }
 188
 189 void Thread::ThreadMain() {
 190   {
 191     // The message loop for this thread.
 192     // Allocated on the heap to centralize any leak reports at this line.
 193     scoped_ptr<MessageLoop> message_loop;
 194     if (!startup_data_->options.message_pump_factory.is_null()) {
 195       message_loop.reset(
 196           new MessageLoop(startup_data_->options.message_pump_factory.Run()));
 197     } else {
 198       message_loop.reset(
 199           new MessageLoop(startup_data_->options.message_loop_type));
 200     }
 201
 202     // Complete the initialization of our Thread object.
 203     thread_id_ = PlatformThread::CurrentId();
 204     PlatformThread::SetName(name_.c_str());
 205     ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
 206     message_loop->set_thread_name(name_);
 207     message_loop->SetTimerSlack(startup_data_->options.timer_slack);
 208     message_loop_ = message_loop.get();
 209
 210 #if defined(OS_WIN)
 211     scoped_ptr<win::ScopedCOMInitializer> com_initializer;
 212     if (com_status_ != NONE) {
 213       com_initializer.reset((com_status_ == STA) ?
 214           new win::ScopedCOMInitializer() :
 215           new win::ScopedCOMInitializer(win::ScopedCOMInitializer::kMTA));
 216     }
 217 #endif
 218
 219     // Let the thread do extra initialization.
 220     // Let's do this before signaling we are started.
 221     Init();
 222
 223     running_ = true;
 224     startup_data_->event.Signal();
 225     // startup_data_ can't be touched anymore since the starting thread is now
 226     // unlocked.
 227
 228     Run(message_loop_);
 229     running_ = false;
 230
 231     // Let the thread do extra cleanup.
 232     CleanUp();
 233
 234 #if defined(OS_WIN)
 235     com_initializer.reset();
 236 #endif
 237
 238     // Assert that MessageLoop::Quit was called by ThreadQuitHelper.
 239     DCHECK(GetThreadWasQuitProperly());
 240
 241     // We can't receive messages anymore.
 242     message_loop_ = NULL;
 243   }
 244 }
 245
 246 }  // namespace base