Man Epoll_wait en anglais
EPOLL_WAIT(2)              Linux Programmer's Manual             EPOLL_WAIT(2)



 

NAME


       epoll_wait - wait for an I/O event on an epoll file descriptor

 

SYNOPSIS


       #include 

       int epoll_wait(int epfd, struct epoll_event * events,
                      int maxevents, int timeout);

 

DESCRIPTION






       Wait for events on the epoll file descriptor epfd for a maximum time of
       timeout milliseconds. The memory area pointed to by events will contain
       the  events that will be available for the caller.  Up to maxevents are
       returned by epoll_wait(2).  The maxevents  parameter  must  be  greater
       than  zero. Specifying a timeout of -1 makes epoll_wait(2) wait indefi-
       nitely, while specifying a timeout equal to zero makes epoll_wait(2) to
       return  immediately  even if no events are available (return code equal
       to zero).  The struct epoll_event is defined as :


           typedef union epoll_data {
               void *ptr;
               int fd;
               __uint32_t u32;
               __uint64_t u64;
           } epoll_data_t;

           struct epoll_event {
               __uint32_t events;      /* Epoll events */
               epoll_data_t data;      /* User data variable */
           };


       The data of each returned structure will contain the same data the user
       set  with a epoll_ctl(2) (EPOLL_CTL_ADD,EPOLL_CTL_MOD) while the events
       member will contain the returned event bit field.

 

RETURN VALUE


       When successful, epoll_wait(2) returns the number of  file  descriptors
       ready for the requested I/O, or zero if no file descriptor became ready
       during the requested  timeout  milliseconds.   When  an  error  occurs,
       epoll_wait(2) returns -1 and errno is set appropriately.

 

ERRORS


       EBADF  epfd is not a valid file descriptor.

       EFAULT The  memory  area  pointed  to  by events is not accessible with
              write permissions.

       EINTR  The call was interrupted by a signal handler before any  of  the
              requested events occurred or the timeout expired.

       EINVAL epfd  is not an epoll file descriptor, or maxevents is less than
              or equal to zero.

 

CONFORMING TO


       epoll_wait(2) is a new API introduced  in  Linux  kernel  2.5.44.   The
       interface should be finalized by Linux kernel 2.5.66.

 

SEE ALSO


       epoll_create(2), epoll_ctl(2), epoll(7)



Linux                           23 October 2002                  EPOLL_WAIT(2)