owacoder owacoder - 2 months ago 17
C++ Question

Boost.Asio socket destructor closes connection?

What exactly does the destructor of

boost::asio::ip::tcp::socket
do? I can't tell, even after scouring Boost docs and source code, if I need to use

socket->shutdown(boost::asio::ip::tcp::socket::shutdown_both);
socket->close();


before calling

delete socket;


Do I need to close the socket manually, or does the destructor handle this?

Answer

When a socket is destroyed, it will be closed as-if by socket.close(ec) during the destruction of the socket.

I/O objects, such as socket, derive from basic_io_object. Within the basic_io_object destructor, destroy() will be invoked on the I/O object's I/O service, passing in an instance of the implementation_type on which the I/O object's service will operate. In the case of socket, destroy() will be invoked on a type that fulfills the SocketService type requirement, closing the underlying socket. In the documentation below, a is an instance of a socket service class, and b is an instance of the implementation_type for the socket service class:

a.destroy(b):

[...] Implicitly cancels asynchronous operations, as if by calling a.close(b, ec).

a.close(b, ec):

If a.is_open() is true, causes any outstanding asynchronous operations to complete as soon as possible. Handlers for cancelled operations shall be passed the error code error::operation_aborted.

post: !a.is_open(b).

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