: wakerfd_(::eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC)), loop_(loop),

wakerchannel_(new Channel(loop, wakerfd_)) {

if (wakerfd_ < 0) {

#ifdef USE_STD_COUT

std::cout << "LOG_SYSERR: "

<< "Failed in eventfd" << std::endl;

#endif

abort();

}

wakerchannel_->setReadCallback(std::bind(&AsyncWaker::handleRead, this));

wakerchannel_->enableReading();

loop_->assertInLoopThread();

// 和wakeup函数对应，wakeup函数实际上是写事件，handleRead为对应的读事件

uint64_t one = 1;

ssize_t n = ::read(wakerfd_, &one, sizeof one);

// 判断读取的字节是不是 one对应的字节数

if (n != sizeof one) {

#ifdef USE_STD_COUT

std::cout << "LOG_ERROR: "

<< "AsyncWaker::handleRead() reads " << n

<< " bytes instead of 8";

#endif

}

uint64_t one = 1;

ssize_t n = ::write(wakerfd_, &one, sizeof one);

// 判断写入的字节是不是 one对应的字节数

if (n != sizeof one) {

#ifdef USE_STD_COUT

std::cout << "LOG_ERROR: "

<< "AsyncWaker::wakeup() writes " << n << " bytes instead of 8"

<< std::endl;

#endif

}

}