How to let a thread which blocks on recv() exit gracefully?

Question

There is a thread likes this:

{  
    ......    
    while (1)
    {
        recv(socket, buffer, sizeof(buffer), 0);
        ......
    }
    close(socket         


        

Answer 1

Declare a global exit flag:

int bExit = 0;

Let the cirtical parts test it:

 while(1)
 {
   ssize_t result = recv(socket, buffer, sizeof(buffer), 0);
   if ((-1 == result) && (EINTR == error) && bExit) 
   {
     break;
   }

   ...
 }

To break your reader, first set the exit flag

bExit = 1;

then send a signal to the reader thread

pthread_kill(pthreadReader, SIGUSR1);

---

Note: What I left out in this example is the protection of bExit against concurrent access.

This might be achieved by using a mutex or an appropriate declaration.