NAME

       io_wait - wait for events

SYNTAX

       #include <libowfat/io.h>

       void io_wait();

DESCRIPTION

       io_wait()  checks  the descriptors that the program is interested in to see whether any of
       them are ready. If none of them are ready, io_wait() tries to pause until one of  them  is
       ready,  so  that  it  does  not  take  time  away  from other programs running on the same
       computer.

       io_wait pays attention to timeouts: if a descriptor reaches its timeout, and  the  program
       is interested in reading or writing that descriptor, io_wait will return promptly.

       Under  some  circumstances, io_wait will return even though no interesting descriptors are
       ready. Do not assume that a descriptor is ready merely because io_wait has returned.

       io_wait is not interrupted by the delivery of a signal. Programs that expect  interruption
       are  unreliable:  they will block if the same signal is delivered a moment before io_wait.
       The correct way to handle signals is with the self-pipe trick.

NOTE

       Depending on the  underlying  operating  system  primitive,  there  is  a  potential  race
       condition  to  be aware of. Some event notification mechanisms (for example, kqueue on BSD
       and epoll on Linux) will return multiple events. If your application operates on pairs  of
       file  descriptors  (a  proxy  server  maybe),  and  an error on one descriptor can lead to
       closing the other descriptor, then an outstanding event on the other descriptor can  still
       be  queued  for  delivery  to you. Be prepared to receive events for a descriptor that has
       already been closed.

SEE ALSO

       io_waituntil(3), io_check(3), io_wantread(3), io_wantwrite(3), io_fd(3)

                                                                                       io_wait(3)