c++ - Boost::asio::write上的互斥不起作用

Question

我正在尝试制作一个异步tcp客户端(发送另一个请求之前，它不会等待请求的结果)。
请求方法如下所示:

std::future<void> AsyncClient::SomeRequestMethod(sometype& parameter)
{
    return std::async(
        std::launch::async,
        [&]()
        {
            // Gonna send a json. ';' at the end of a json separates the requests.
            const std::string requestJson = Serializer::ArraySumRequest(numbers) + ';';
            boost::system::error_code err;

            write(requestJson, err);
            // Other stuff.

write方法调用boost::asio::write像这样:

void AsyncClient::write(const std::string& strToWrite, boost::system::error_code& err)
{
    // m_writeMutex is a class member I use to synchronize writing.
    std::lock_guard<std::mutex> lock(m_writeMutex);
    boost::asio::write(m_socket,
        boost::asio::buffer(strToWrite), err);
}

但是看起来仍然有多个线程并发写入，就像我在服务器中收到的一样:

{"Key":"Val{"Key":Value};ue"};

我该怎么办？

Answer 1

您确实将锁保护装置围绕写入asio 。如您所见，无法保证另一端将使用相同的防护程序对其进行处理。
您应该将保护放在您需要的地方，从api上的上写json jsont_rstrong:

void AsyncClient::write(const std::string& strToWrite, boost::system::error_code& err)
{
 // m_writeMutex is a class member I use to synchronize writing.
// std::lock_guard<std::mutex> lock(m_writeMutex);
 boost::asio::write(m_socket,
 boost::asio::buffer(strToWrite), err);
}

return std::async(
 std::launch::async,
 [&]()
 {
 std::lock_guard<std::mutex> lock(m_writeMutex); // <--- here

 // Gonna send a json. ';' at the end of a json separates the requests.
 const std::string requestJson = Serializer::ArraySumRequest(numbers) + ';';
 boost::system::error_code err;

 write(requestJson, err);
 // Other stuff.