How to Break C++ Accept Function?

Question

When doing socket programming, with multi-threading,

if a thread is blocked on Accept Function,

and main thread is trying to shut down the process,

how to break the accept function in order to pthread_join safely?

I have vague memory of how to do this by connection itself to its own port in order to break the accept function.

Any solution will be thankful.

Cheers

Answer 1

Some choices:

a) Use non-blocking

b) Use AcceptEx() to wait on an extra signal, (Windows)

c) Close the listening socket from another thread to make Accept() return with an error/exception.

d) Open a temporary local connection from another thread to make Accept() return with the temp connection

Answer 2

The typical approach to this is not to use accept() unless there is something to accept! The way to do this is to poll() the corresponding socket with a suitable time-out in a loop. The loop checks if it is meant to exit because a suitably synchronized flag was set.

An alternative is to send the blocked thread a signal, e.g., using pthread_kill(). This gets out of the blocked accept() with a suitable error indication. Again, the next step is to check some flag to see if the thread is meant to exit. My preference is the first approach, though.