tree b6af930de3c7ebdf67a1fd64018749ba3278bc14
parent 033cd9d78c9930677f28d150d8bbb10f50cf6f3d
author Willy Tarreau <w@1wt.eu> 1389369525 +0100
committer Willy Tarreau <w@1wt.eu> 1390693350 +0100
encoding latin1

MAJOR: polling: rework the whole polling system

This commit heavily changes the polling system in order to definitely
fix the frequent breakage of SSL which needs to remember the last
EAGAIN before deciding whether to poll or not. Now we have a state per
direction for each FD, as opposed to a previous and current state
previously. An FD can have up to 8 different states for each direction,
each of which being the result of a 3-bit combination. These 3 bits
indicate a wish to access the FD, the readiness of the FD and the
subscription of the FD to the polling system.

This means that it will now be possible to remember the state of a
file descriptor across disable/enable sequences that generally happen
during forwarding, where enabling reading on a previously disabled FD
would result in forgetting the EAGAIN flag it met last time.

Several new state manipulation functions have been introduced or
adapted :
  - fd_want_{recv,send} : enable receiving/sending on the FD regardless
    of its state (sets the ACTIVE flag) ;

  - fd_stop_{recv,send} : stop receiving/sending on the FD regardless
    of its state (clears the ACTIVE flag) ;

  - fd_cant_{recv,send} : report a failure to receive/send on the FD
    corresponding to EAGAIN (clears the READY flag) ;

  - fd_may_{recv,send}  : report the ability to receive/send on the FD
    as reported by poll() (sets the READY flag) ;

Some functions are used to report the current FD status :

  - fd_{recv,send}_active
  - fd_{recv,send}_ready
  - fd_{recv,send}_polled

Some functions were removed :
  - fd_ev_clr(), fd_ev_set(), fd_ev_rem(), fd_ev_wai()

The POLLHUP/POLLERR flags are now reported as ready so that the I/O layers
knows it can try to access the file descriptor to get this information.

In order to simplify the conditions to add/remove cache entries, a new
function fd_alloc_or_release_cache_entry() was created to be used from
pollers while scanning for updates.

The following pollers have been updated :

   ev_select() : done, built, tested on Linux 3.10
   ev_poll()   : done, built, tested on Linux 3.10
   ev_epoll()  : done, built, tested on Linux 3.10 & 3.13
   ev_kqueue() : done, built, tested on OpenBSD 5.2