thread.cc revision 3f50c38dc070f4bb515c1b64450dae14f316474e 
1// Copyright (c) 2006-2009 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/lazy_instance.h"
8#include "base/third_party/dynamic_annotations/dynamic_annotations.h"
9#include "base/threading/thread_local.h"
10#include "base/synchronization/waitable_event.h"
11
12namespace base {
13
14// This task is used to trigger the message loop to exit.
15class ThreadQuitTask : public Task {
16 public:
17  virtual void Run() {
18    MessageLoop::current()->Quit();
19    Thread::SetThreadWasQuitProperly(true);
20  }
21};
22
23// Used to pass data to ThreadMain.  This structure is allocated on the stack
24// from within StartWithOptions.
25struct Thread::StartupData {
26  // We get away with a const reference here because of how we are allocated.
27  const Thread::Options& options;
28
29  // Used to synchronize thread startup.
30  WaitableEvent event;
31
32  explicit StartupData(const Options& opt)
33      : options(opt),
34        event(false, false) {}
35};
36
37Thread::Thread(const char* name)
38    : started_(false),
39      stopping_(false),
40      startup_data_(NULL),
41      thread_(0),
42      message_loop_(NULL),
43      thread_id_(kInvalidThreadId),
44      name_(name) {
45}
46
47Thread::~Thread() {
48  Stop();
49}
50
51namespace {
52
53// We use this thread-local variable to record whether or not a thread exited
54// because its Stop method was called.  This allows us to catch cases where
55// MessageLoop::Quit() is called directly, which is unexpected when using a
56// Thread to setup and run a MessageLoop.
57base::LazyInstance<base::ThreadLocalBoolean> lazy_tls_bool(
58    base::LINKER_INITIALIZED);
59
60}  // namespace
61
62void Thread::SetThreadWasQuitProperly(bool flag) {
63  lazy_tls_bool.Pointer()->Set(flag);
64}
65
66bool Thread::GetThreadWasQuitProperly() {
67  bool quit_properly = true;
68#ifndef NDEBUG
69  quit_properly = lazy_tls_bool.Pointer()->Get();
70#endif
71  return quit_properly;
72}
73
74bool Thread::Start() {
75  return StartWithOptions(Options());
76}
77
78bool Thread::StartWithOptions(const Options& options) {
79  DCHECK(!message_loop_);
80
81  SetThreadWasQuitProperly(false);
82
83  StartupData startup_data(options);
84  startup_data_ = &startup_data;
85
86  if (!PlatformThread::Create(options.stack_size, this, &thread_)) {
87    DLOG(ERROR) << "failed to create thread";
88    startup_data_ = NULL;
89    return false;
90  }
91
92  // Wait for the thread to start and initialize message_loop_
93  startup_data.event.Wait();
94
95  // set it to NULL so we don't keep a pointer to some object on the stack.
96  startup_data_ = NULL;
97  started_ = true;
98
99  DCHECK(message_loop_);
100  return true;
101}
102
103void Thread::Stop() {
104  if (!thread_was_started())
105    return;
106
107  StopSoon();
108
109  // Wait for the thread to exit.
110  //
111  // TODO(darin): Unfortunately, we need to keep message_loop_ around until
112  // the thread exits.  Some consumers are abusing the API.  Make them stop.
113  //
114  PlatformThread::Join(thread_);
115
116  // The thread should NULL message_loop_ on exit.
117  DCHECK(!message_loop_);
118
119  // The thread no longer needs to be joined.
120  started_ = false;
121
122  stopping_ = false;
123}
124
125void Thread::StopSoon() {
126  // We should only be called on the same thread that started us.
127
128  // Reading thread_id_ without a lock can lead to a benign data race
129  // with ThreadMain, so we annotate it to stay silent under ThreadSanitizer.
130  DCHECK_NE(ANNOTATE_UNPROTECTED_READ(thread_id_), PlatformThread::CurrentId());
131
132  if (stopping_ || !message_loop_)
133    return;
134
135  stopping_ = true;
136  message_loop_->PostTask(FROM_HERE, new ThreadQuitTask());
137}
138
139void Thread::Run(MessageLoop* message_loop) {
140  message_loop->Run();
141}
142
143void Thread::ThreadMain() {
144  {
145    // The message loop for this thread.
146    MessageLoop message_loop(startup_data_->options.message_loop_type);
147
148    // Complete the initialization of our Thread object.
149    thread_id_ = PlatformThread::CurrentId();
150    PlatformThread::SetName(name_.c_str());
151    ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
152    message_loop.set_thread_name(name_);
153    message_loop_ = &message_loop;
154    message_loop_proxy_ = MessageLoopProxy::CreateForCurrentThread();
155
156    // Let the thread do extra initialization.
157    // Let's do this before signaling we are started.
158    Init();
159
160    startup_data_->event.Signal();
161    // startup_data_ can't be touched anymore since the starting thread is now
162    // unlocked.
163
164    Run(message_loop_);
165
166    // Let the thread do extra cleanup.
167    CleanUp();
168
169    // Assert that MessageLoop::Quit was called by ThreadQuitTask.
170    DCHECK(GetThreadWasQuitProperly());
171
172    // We can't receive messages anymore.
173    message_loop_ = NULL;
174    message_loop_proxy_ = NULL;
175  }
176  CleanUpAfterMessageLoopDestruction();
177  thread_id_ = kInvalidThreadId;
178}
179
180}  // namespace base
181