我写了一个包装围绕Boostless ASIO处理所有网络通信。大多数交易所涉及发送多个数据包来回的客户端和服务器之间。我现在已经在那里，如果我嵌套调用ASIO方法，我的方法__throw_bad_function_call();最后一个问题
这里是我的听众：
.HPP
/// \brief Socket object used to manage connections to the remote server.
struct listener : public std::enable_shared_from_this<listener> {
/// \brief Creates an instance of the object and opens a connection to the remote host.
/// \param[in] params Connection parameters.
/// \param[out] ec Errors returned by the OS.
explicit listener(const parameters ¶ms, std::error_code &ec) noexcept;
/// \brief Executes all queued handlers and resets the io_context for another run.
auto execute_handlers() noexcept -> void;
/// \brief Writes data to the socket.
/// \details Writes data to the socket and passes any errors to the callback.
/// \param[in] barray Byte array to send to the server.
/// \param[in] callback Method called when data has been written to the server.
auto write(packet barray, std::function<void(std::error_code ec, std::size_t length)> callback) noexcept -> void;
/// \brief Reads data from the socket.
/// \details Reads that present in the socket and passes the data as a single byte array to the callback.
/// \param[in] callback Method called when data has been written to the server.
auto read(std::function<void(std::error_code ec, packet barray)> callback) noexcept -> void;
private:
/// \brief Underlying OS socket.
std::unique_ptr<asio::generic::stream_protocol::socket> m_socket;
asio::io_context m_context;
asio::local::stream_protocol::endpoint m_endpoint;
/// \brief Connection parameters
parameters m_params;
/// \brief DNS resolver
asio::ip::tcp::resolver m_resolver;
/// \brief Buffer that holds data to be received from the socket. Reset and resized before each call to read().
packet m_buffer;
};
CPP
listener::listener(const parameters ¶ms, std::error_code &ec) noexcept
: m_endpoint{params.domain_socket}, m_params{params}, m_resolver{m_context} {
#if !defined(_WIN32) && !defined(_WIN64)
if (!m_params.domain_socket.empty()) {
m_socket.reset(new asio::generic::stream_protocol::socket(m_context));
m_socket->connect(m_endpoint, ec);
if (ec) {
return;
}
m_socket->non_blocking(true);
return;
}
#endif
m_resolver.async_resolve(m_params.host, std::to_string(m_params.port),
[&](const std::error_code &error, asio::ip::tcp::resolver::results_type results) {
if (error) {
ec = error;
return;
}
//! \todo Add timeout to async_connect
for (const auto &endpoint : results) {
m_socket.reset(new asio::generic::stream_protocol::socket(m_context));
m_socket->async_connect(endpoint.endpoint(), [&](const std::error_code &err_c) {
if (err_c) {
ec = err_c;
return;
}
});
}
});
}
auto listener::execute_handlers() noexcept -> void {
const auto handlers = m_context.run();
m_context.restart();
}
auto listener::write(packet barray, std::function<void(std::error_code ec, std::size_t length)> callback) noexcept
-> void {
asio::async_write(*m_socket, asio::buffer(barray), callback);
}
auto listener::read(std::function<void(std::error_code ec, packet barray)> callback) noexcept -> void {
packet tmp;
tmp.resize(1);
asio::async_read(*m_socket, asio::buffer(tmp), asio::transfer_exactly(1),
[&](std::error_code ec, std::size_t size) {
if (!ec) {
const auto available = m_socket->available();
m_buffer.resize(available);
m_buffer.shrink_to_fit();
asio::async_read(*m_socket, asio::buffer(m_buffer), asio::transfer_all());
}
callback(ec, std::move(m_buffer));
});
}
然后我开始与远程服务器交换，但LLDB告诉我，我们会失败：
auto connection::do_connect(std::function<void(std::error_code ec, sql_state state)> callback) noexcept -> void {
m_listener = std::make_shared<listener>(m_params, ec);
m_listener->execute_handlers();
if (ec) {
callback(ec, state);
}
sql_state state;
const auto startup = write::startup(m_params);
m_listener->write(startup, [&](std::error_code ec, std::size_t length) {
if (ec) {
callback(ec, state);
}
m_listener->read([&](std::error_code ec, packet packet){});
});
m_listener->execute_handlers();
}
在LLDB运行此失败，出现以下跟踪：
Process 82736 launched: '/Users/ruihpacheco/Desktop/databaseclient/build_ninja/tests/integration/integration' (x86_64)
Process 82736 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
frame #0: 0x0000000100178118 integration`std::__1::function<void (std::__1::error_code, std::__1::vector<nonstd::byte, std::__1::allocator<nonstd::byte> >)>::operator(this=0x00007ffeefbfd780, __arg=(__val_ = 0, __cat_ = 0x00007fffa6cd6cd8), __arg=size=329)(std::__1::error_code, std::__1::vector<nonstd::byte, std::__1::allocator<nonstd::byte> >) const at functional:1913
1910 {
1911 if (__f_ == 0)
1912 __throw_bad_function_call();
-> 1913 return (*__f_)(_VSTD::forward<_ArgTypes>(__arg)...);
1914 }
1915
1916 #ifndef _LIBCPP_NO_RTTI
Target 0: (integration) stopped.
这感觉就像它应该工作...
看来你的问题开始异步操作，这需要缓冲局部变量。
auto listener::write(packet barray, std::function<void(std::error_code ec, std::size_t length)> callback) noexcept
-> void {
asio::async_write(*m_socket, asio::buffer(barray), callback);
}
barray是内部write，async_write立即返回局部变量，但asio::buffer()仅返回包装器传递的数据（指针数据和它的大小）时，没有数据被复制。 write结束，barray被破坏，async_write得到缓冲到删除的数据..
同样的用
auto listener::read(std::function<void(std::error_code ec, packet barray)> callback) noexcept -> void {
packet tmp;
tmp.resize(1);
asio::async_read(*m_socket, asio::buffer(tmp), asio::transfer_exactly(1),
[&](std::error_code ec, std::size_t size) {
if (!ec) {
const auto available = m_socket->available();
m_buffer.resize(available);
m_buffer.shrink_to_fit();
asio::async_read(*m_socket, asio::buffer(m_buffer), asio::transfer_all());
}
callback(ec, std::move(m_buffer));
});
async_read需要buffer(tmp)，其中tmp是本地的。 async_read也立即返回，因此，当调用处理程序，tmp不存在。
编辑
约listener::read方法的一些话：
auto listener::read(
std::function<void(std::error_code ec, packet barray)> callback) noexcept -> void // [1]
{
packet tmp;
tmp.resize(1);
asio::async_read(*m_socket, asio::buffer(tmp), asio::transfer_exactly(1),
[&](std::error_code ec, std::size_t size) { // [2]
if (!ec) {
const auto available = m_socket->available();
m_buffer.resize(available);
m_buffer.shrink_to_fit();
asio::async_read(*m_socket, asio::buffer(m_buffer), asio::transfer_all()); // [3]
}
callback(ec, std::move(m_buffer)); // [4]
});
}
[1]回调由值来传递
[2]拉姆达捕获所有参考，所以没有callback的复制时，闭合保持参照局部变量，在其中悬挂[4]您呼叫闭合callback(ec,std::move(m_buffer))因为async_read立即和listener::read端返回
[3]与[4]很奇怪，async_read立即返回，则通过buffer调用m_buffer时ayns_read，async_read返回（读异步操作正在被执行）和回调被称为该移动m_buffer（它改变其用于通过异步对象操作！），你应该等到async_read处理程序被调用，然后你可以移动到m_buffer回调
主要的问题：在我看来，这个问题是由参考callback方法传递listener::read。当处理器被调用它调用callback(..)上晃来晃去参考。尝试按值传递callback：
[&,callback /*pass by value*/](std::error_code ec, std::size_t size)
{
if (!ec)
{
const auto available = m_socket->available();
m_buffer.resize(available);
m_buffer.shrink_to_fit();
asio::async_read(*m_socket, asio::buffer(m_buffer), asio::transfer_all());
}
callback(ec, std::move(m_buffer));
});