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.
ThreadQuitHelper()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
StartupDatabase::Thread::StartupData47 explicit StartupData(const Options& opt)
48 : options(opt),
49 event(false, false) {}
50 };
51
Options()52 Thread::Options::Options()
53 : message_loop_type(MessageLoop::TYPE_DEFAULT),
54 stack_size(0) {
55 }
56
Options(MessageLoop::Type type,size_t size)57 Thread::Options::Options(MessageLoop::Type type,
58 size_t size)
59 : message_loop_type(type),
60 stack_size(size) {
61 }
62
~Options()63 Thread::Options::~Options() {
64 }
65
Thread(const std::string & name)66 Thread::Thread(const std::string& 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
~Thread()81 Thread::~Thread() {
82 Stop();
83 }
84
Start()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
StartWithOptions(const Options & options)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
Stop()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
StopSoon()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
IsRunning() const160 bool Thread::IsRunning() const {
161 return running_;
162 }
163
SetPriority(ThreadPriority priority)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
Run(MessageLoop * message_loop)171 void Thread::Run(MessageLoop* message_loop) {
172 message_loop->Run();
173 }
174
SetThreadWasQuitProperly(bool flag)175 void Thread::SetThreadWasQuitProperly(bool flag) {
176 lazy_tls_bool.Pointer()->Set(flag);
177 }
178
GetThreadWasQuitProperly()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
ThreadMain()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
244