tor-browser

thread.cc (5919B)

---

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/thread.h"

#include "base/string_util.h"
#include "base/thread_local.h"
#include "base/waitable_event.h"
#include "GeckoProfiler.h"
#include "mozilla/EventQueue.h"
#include "mozilla/IOInterposer.h"
#include "mozilla/ThreadEventQueue.h"
#include "nsThreadUtils.h"
#include "nsThreadManager.h"

namespace base {

// This task is used to trigger the message loop to exit.
class ThreadQuitTask : public mozilla::Runnable {
public:
 ThreadQuitTask() : mozilla::Runnable("ThreadQuitTask") {}
 NS_IMETHOD Run() override {
   MessageLoop::current()->Quit();
   Thread::SetThreadWasQuitProperly(true);
   return NS_OK;
 }
};

// Used to pass data to ThreadMain.  This structure is allocated on the stack
// from within StartWithOptions.
struct Thread::StartupData {
 // We get away with a const reference here because of how we are allocated.
 const Thread::Options& options;

 // Used to synchronize thread startup.
 WaitableEvent event;

 explicit StartupData(const Options& opt)
     : options(opt), event(false, false) {}
};

Thread::Thread(const char* name)
   : startup_data_(NULL),
     thread_(0),
     message_loop_(NULL),
     thread_id_(0),
     name_(name) {
 MOZ_COUNT_CTOR(base::Thread);
}

Thread::~Thread() {
 MOZ_COUNT_DTOR(base::Thread);
 Stop();
}

namespace {

// We use this thread-local variable to record whether or not a thread exited
// because its Stop method was called.  This allows us to catch cases where
// MessageLoop::Quit() is called directly, which is unexpected when using a
// Thread to setup and run a MessageLoop.

static base::ThreadLocalBoolean& get_tls_bool() {
 static base::ThreadLocalBoolean tls_ptr;
 return tls_ptr;
}

}  // namespace

void Thread::SetThreadWasQuitProperly(bool flag) { get_tls_bool().Set(flag); }

bool Thread::GetThreadWasQuitProperly() {
 bool quit_properly = true;
#ifndef NDEBUG
 quit_properly = get_tls_bool().Get();
#endif
 return quit_properly;
}

bool Thread::Start() { return StartWithOptions(Options()); }

bool Thread::StartWithOptions(const Options& options) {
 DCHECK(!message_loop_);

 SetThreadWasQuitProperly(false);

 StartupData startup_data(options);
 startup_data_ = &startup_data;

 if (!PlatformThread::Create(options.stack_size, this, &thread_)) {
   DLOG(ERROR) << "failed to create thread";
   startup_data_ = NULL;  // Record that we failed to start.
   return false;
 }

 // Wait for the thread to start and initialize message_loop_
 startup_data.event.Wait();

 DCHECK(message_loop_);
 return true;
}

void Thread::Stop() {
 if (!thread_was_started()) return;

 // We should only be called on the same thread that started us.
 DCHECK_NE(thread_id_, PlatformThread::CurrentId());

 // StopSoon may have already been called.
 if (message_loop_) {
   RefPtr<ThreadQuitTask> task = new ThreadQuitTask();
   message_loop_->PostTask(task.forget());
 }

 // Wait for the thread to exit.  It should already have terminated but make
 // sure this assumption is valid.
 //
 // TODO(darin): Unfortunately, we need to keep message_loop_ around until
 // the thread exits.  Some consumers are abusing the API.  Make them stop.
 //
 PlatformThread::Join(thread_);

 // The thread can't receive messages anymore.
 message_loop_ = NULL;

 // The thread no longer needs to be joined.
 startup_data_ = NULL;
}

void Thread::StopSoon() {
 if (!message_loop_) return;

 // We should only be called on the same thread that started us.
 DCHECK_NE(thread_id_, PlatformThread::CurrentId());

 // We had better have a message loop at this point!  If we do not, then it
 // most likely means that the thread terminated unexpectedly, probably due
 // to someone calling Quit() on our message loop directly.
 DCHECK(message_loop_);

 RefPtr<ThreadQuitTask> task = new ThreadQuitTask();
 message_loop_->PostTask(task.forget());
}

void Thread::ThreadMain() {
 nsCOMPtr<nsIThread> xpcomThread;
 auto loopType = startup_data_->options.message_loop_type;
 if (loopType == MessageLoop::TYPE_MOZILLA_NONMAINTHREAD ||
     loopType == MessageLoop::TYPE_MOZILLA_NONMAINUITHREAD) {
   auto queue = mozilla::MakeRefPtr<mozilla::ThreadEventQueue>(
       mozilla::MakeUnique<mozilla::EventQueue>());
   xpcomThread = nsThreadManager::get().CreateCurrentThread(queue);
 } else {
   xpcomThread = NS_GetCurrentThread();
 }

 AUTO_PROFILER_REGISTER_THREAD(name_.c_str());
 mozilla::IOInterposer::RegisterCurrentThread();

 // The message loop for this thread.
 MessageLoop message_loop(startup_data_->options.message_loop_type,
                          xpcomThread);

 xpcomThread = nullptr;

 // Complete the initialization of our Thread object.
 thread_id_ = PlatformThread::CurrentId();
 PlatformThread::SetName(name_.c_str());
 NS_SetCurrentThreadName(name_.c_str());
 message_loop.set_thread_name(name_);
 message_loop.set_hang_timeouts(startup_data_->options.transient_hang_timeout,
                                startup_data_->options.permanent_hang_timeout);
 message_loop_ = &message_loop;

 // Let the thread do extra initialization.
 // Let's do this before signaling we are started.
 Init();

 startup_data_->event.Signal();
 // startup_data_ can't be touched anymore since the starting thread is now
 // unlocked.

 message_loop.Run();

 // Let the thread do extra cleanup.
 CleanUp();

 // Assert that MessageLoop::Quit was called by ThreadQuitTask.
 DCHECK(GetThreadWasQuitProperly());

 mozilla::IOInterposer::UnregisterCurrentThread();

 // We can't receive messages anymore.
 message_loop_ = NULL;
 thread_id_ = 0;
}

}  // namespace base