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       stack_size(0) {
  55 }
  56
  57 Thread::Options::Options(MessageLoop::Type type,
  58                          size_t size)
  59     : message_loop_type(type),
  60       stack_size(size) {
  61 }
  62
  63 Thread::Options::~Options() {
  64 }
  65
  66 Thread::Thread(const char* name)
  67     :
  68 #if defined(OS_WIN)
  69       com_status_(NONE),
  70 #endif
  71       started_(false),
  72       stopping_(false),
  73       running_(false),
  74       startup_data_(NULL),
  75       thread_(0),
  76       message_loop_(NULL),
  77       thread_id_(kInvalidThreadId),
  78       name_(name) {
  79 }
  80
  81 Thread::~Thread() {
  82   Stop();
  83 }
  84
  85 bool Thread::Start() {
  86   Options options;
  87 #if defined(OS_WIN)
  88   if (com_status_ == STA)
  89     options.message_loop_type = MessageLoop::TYPE_UI;
  90 #endif
  91   return StartWithOptions(options);
  92 }
  93
  94 bool Thread::StartWithOptions(const Options& options) {
  95   DCHECK(!message_loop_);
  96 #if defined(OS_WIN)
  97   DCHECK((com_status_ != STA) ||
  98       (options.message_loop_type == MessageLoop::TYPE_UI));
  99 #endif
 100
 101   SetThreadWasQuitProperly(false);
 102
 103   StartupData startup_data(options);
 104   startup_data_ = &startup_data;
 105
 106   if (!PlatformThread::Create(options.stack_size, this, &thread_)) {
 107     DLOG(ERROR) << "failed to create thread";
 108     startup_data_ = NULL;
 109     return false;
 110   }
 111
 112   // Wait for the thread to start and initialize message_loop_
 113   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 114   startup_data.event.Wait();
 115
 116   // set it to NULL so we don't keep a pointer to some object on the stack.
 117   startup_data_ = NULL;
 118   started_ = true;
 119
 120   DCHECK(message_loop_);
 121   return true;
 122 }
 123
 124 void Thread::Stop() {
 125   if (!started_)
 126     return;
 127
 128   StopSoon();
 129
 130   // Wait for the thread to exit.
 131   //
 132   // TODO(darin): Unfortunately, we need to keep message_loop_ around until
 133   // the thread exits.  Some consumers are abusing the API.  Make them stop.
 134   //
 135   PlatformThread::Join(thread_);
 136
 137   // The thread should NULL message_loop_ on exit.
 138   DCHECK(!message_loop_);
 139
 140   // The thread no longer needs to be joined.
 141   started_ = false;
 142
 143   stopping_ = false;
 144 }
 145
 146 void Thread::StopSoon() {
 147   // We should only be called on the same thread that started us.
 148
 149   // Reading thread_id_ without a lock can lead to a benign data race
 150   // with ThreadMain, so we annotate it to stay silent under ThreadSanitizer.
 151   DCHECK_NE(ANNOTATE_UNPROTECTED_READ(thread_id_), PlatformThread::CurrentId());
 152
 153   if (stopping_ || !message_loop_)
 154     return;
 155
 156   stopping_ = true;
 157   message_loop_->PostTask(FROM_HERE, base::Bind(&ThreadQuitHelper));
 158 }
 159
 160 bool Thread::IsRunning() const {
 161   return running_;
 162 }
 163
 164 void Thread::SetPriority(ThreadPriority priority) {
 165   // The thread must be started (and id known) for this to be
 166   // compatible with all platforms.
 167   DCHECK_NE(thread_id_, kInvalidThreadId);
 168   PlatformThread::SetThreadPriority(thread_, priority);
 169 }
 170
 171 void Thread::Run(MessageLoop* message_loop) {
 172   message_loop->Run();
 173 }
 174
 175 void Thread::SetThreadWasQuitProperly(bool flag) {
 176   lazy_tls_bool.Pointer()->Set(flag);
 177 }
 178
 179 bool Thread::GetThreadWasQuitProperly() {
 180   bool quit_properly = true;
 181 #ifndef NDEBUG
 182   quit_properly = lazy_tls_bool.Pointer()->Get();
 183 #endif
 184   return quit_properly;
 185 }
 186
 187 void Thread::ThreadMain() {
 188   {
 189     // The message loop for this thread.
 190     // Allocated on the heap to centralize any leak reports at this line.
 191     scoped_ptr<MessageLoop> message_loop;
 192     if (!startup_data_->options.message_pump_factory.is_null()) {
 193       message_loop.reset(
 194           new MessageLoop(startup_data_->options.message_pump_factory.Run()));
 195     } else {
 196       message_loop.reset(
 197           new MessageLoop(startup_data_->options.message_loop_type));
 198     }
 199
 200     // Complete the initialization of our Thread object.
 201     thread_id_ = PlatformThread::CurrentId();
 202     PlatformThread::SetName(name_.c_str());
 203     ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
 204     message_loop->set_thread_name(name_);
 205     message_loop_ = message_loop.get();
 206
 207 #if defined(OS_WIN)
 208     scoped_ptr<win::ScopedCOMInitializer> com_initializer;
 209     if (com_status_ != NONE) {
 210       com_initializer.reset((com_status_ == STA) ?
 211           new win::ScopedCOMInitializer() :
 212           new win::ScopedCOMInitializer(win::ScopedCOMInitializer::kMTA));
 213     }
 214 #endif
 215
 216     // Let the thread do extra initialization.
 217     // Let's do this before signaling we are started.
 218     Init();
 219
 220     running_ = true;
 221     startup_data_->event.Signal();
 222     // startup_data_ can't be touched anymore since the starting thread is now
 223     // unlocked.
 224
 225     Run(message_loop_);
 226     running_ = false;
 227
 228     // Let the thread do extra cleanup.
 229     CleanUp();
 230
 231 #if defined(OS_WIN)
 232     com_initializer.reset();
 233 #endif
 234
 235     // Assert that MessageLoop::Quit was called by ThreadQuitHelper.
 236     DCHECK(GetThreadWasQuitProperly());
 237
 238     // We can't receive messages anymore.
 239     message_loop_ = NULL;
 240   }
 241 }
 242
 243 }  // namespace base