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ev_kqueue.c

/*
 * FD polling functions for FreeBSD kqueue()
 *
 * Copyright 2000-2007 Willy Tarreau <w@1wt.eu>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 * Note: not knowing much about kqueue, I had to rely on OpenBSD's detailed man
 * page and to check how it was implemented in lighttpd to understand it better.
 * But it is possible that I got things wrong.
 *
 */

#include <unistd.h>
#include <sys/time.h>
#include <sys/types.h>

#include <sys/event.h>
#include <sys/time.h>

#include <common/compat.h>
#include <common/config.h>
#include <common/time.h>
#include <common/tools.h>

#include <types/fd.h>
#include <types/global.h>

#include <proto/fd.h>
#include <proto/task.h>

/* private data */
static fd_set *fd_evts[2];
static int kqueue_fd;
static struct kevent *kev = NULL;

/* speeds up conversion of DIR_RD/DIR_WR to EVFILT* */
static const int dir2filt[2] = { EVFILT_READ, EVFILT_WRITE };

/* completes a change list for deletion */
REGPRM3 static int kqev_del(struct kevent *kev, const int fd, const int dir)
{
      if (FD_ISSET(fd, fd_evts[dir])) {
            FD_CLR(fd, fd_evts[dir]);
            EV_SET(kev, fd, dir2filt[dir], EV_DELETE, 0, 0, NULL);
            return 1;
      }
      return 0;
}

/*
 * Returns non-zero if direction <dir> is already set for <fd>.
 */
REGPRM2 static int __fd_is_set(const int fd, int dir)
{
      return FD_ISSET(fd, fd_evts[dir]);
}

REGPRM2 static int __fd_set(const int fd, int dir)
{
      /* if the value was set, do nothing */
      if (FD_ISSET(fd, fd_evts[dir]))
            return 0;

      FD_SET(fd, fd_evts[dir]);
      EV_SET(kev, fd, dir2filt[dir], EV_ADD, 0, 0, NULL);
      kevent(kqueue_fd, kev, 1, NULL, 0, NULL);
      return 1;
}

REGPRM2 static int __fd_clr(const int fd, int dir)
{
      if (!kqev_del(kev, fd, dir))
            return 0;
      kevent(kqueue_fd, kev, 1, NULL, 0, NULL);
      return 1;
}

REGPRM1 static void __fd_rem(int fd)
{
      int changes = 0;

      changes += kqev_del(&kev[changes], fd, DIR_RD);
      changes += kqev_del(&kev[changes], fd, DIR_WR);

      if (changes)
            kevent(kqueue_fd, kev, changes, NULL, 0, NULL);
}

REGPRM1 static void __fd_clo(int fd)
{
      FD_CLR(fd, fd_evts[DIR_RD]);
      FD_CLR(fd, fd_evts[DIR_WR]);
}

/*
 * kqueue() poller
 */
REGPRM2 static void _do_poll(struct poller *p, struct timeval *exp)
{
      int status;
      int count, fd;
      struct timespec timeout, *to_ptr;

      to_ptr = NULL;    // no timeout
      if (tv_isset(exp)) {
            struct timeval delta;

            if (tv_isge(&now, exp))
                  delta.tv_sec = delta.tv_usec = 0;
            else
                  tv_remain(&now, exp, &delta);

            timeout.tv_sec  = delta.tv_sec;
            timeout.tv_nsec = delta.tv_usec * 1000;
            to_ptr = &timeout;
      }

      fd = MIN(maxfd, global.tune.maxpollevents);
      status = kevent(kqueue_fd, // int kq
                  NULL,      // const struct kevent *changelist
                  0,         // int nchanges
                  kev,       // struct kevent *eventlist
                  fd,        // int nevents
                  to_ptr);   // const struct timespec *timeout
      tv_now(&now);

      for (count = 0; count < status; count++) {
            fd = kev[count].ident;
            if (kev[count].filter ==  EVFILT_READ) {
                  if (FD_ISSET(fd, fd_evts[DIR_RD])) {
                        if (fdtab[fd].state == FD_STCLOSE)
                              continue;
                        fdtab[fd].cb[DIR_RD].f(fd);
                  }
            } else if (kev[count].filter ==  EVFILT_WRITE) {
                  if (FD_ISSET(fd, fd_evts[DIR_WR])) {
                        if (fdtab[fd].state == FD_STCLOSE)
                              continue;
                        fdtab[fd].cb[DIR_WR].f(fd);
                  }
            }
      }
}

/*
 * Initialization of the kqueue() poller.
 * Returns 0 in case of failure, non-zero in case of success. If it fails, it
 * disables the poller by setting its pref to 0.
 */
REGPRM1 static int _do_init(struct poller *p)
{
      __label__ fail_wevt, fail_revt, fail_fd;
      int fd_set_bytes;

      p->private = NULL;
      fd_set_bytes = sizeof(fd_set) * (global.maxsock + FD_SETSIZE - 1) / FD_SETSIZE;

      kqueue_fd = kqueue();
      if (kqueue_fd < 0)
            goto fail_fd;

      kev = (struct kevent*)calloc(1, sizeof(struct kevent) * global.tune.maxpollevents);

      if (kev == NULL)
            goto fail_kev;
            
      if ((fd_evts[DIR_RD] = (fd_set *)calloc(1, fd_set_bytes)) == NULL)
            goto fail_revt;

      if ((fd_evts[DIR_WR] = (fd_set *)calloc(1, fd_set_bytes)) == NULL)
            goto fail_wevt;

      return 1;

 fail_wevt:
      free(fd_evts[DIR_RD]);
 fail_revt:
      free(kev);
 fail_kev:
      close(kqueue_fd);
      kqueue_fd = 0;
 fail_fd:
      p->pref = 0;
      return 0;
}

/*
 * Termination of the kqueue() poller.
 * Memory is released and the poller is marked as unselectable.
 */
REGPRM1 static void _do_term(struct poller *p)
{
      if (fd_evts[DIR_WR])
            free(fd_evts[DIR_WR]);
      if (fd_evts[DIR_RD])
            free(fd_evts[DIR_RD]);
      if (kev)
            free(kev);
      close(kqueue_fd);
      kqueue_fd = 0;

      p->private = NULL;
      p->pref = 0;
}

/*
 * Check that the poller works.
 * Returns 1 if OK, otherwise 0.
 */
REGPRM1 static int _do_test(struct poller *p)
{
      int fd;

      fd = kqueue();
      if (fd < 0)
            return 0;
      close(fd);
      return 1;
}

/*
 * Recreate the kqueue file descriptor after a fork(). Returns 1 if OK,
 * otherwise 0. Note that some pollers need to be reopened after a fork()
 * (such as kqueue), and some others may fail to do so in a chroot.
 */
REGPRM1 static int _do_fork(struct poller *p)
{
      close(kqueue_fd);
      kqueue_fd = kqueue();
      if (kqueue_fd < 0)
            return 0;
      return 1;
}

/*
 * It is a constructor, which means that it will automatically be called before
 * main(). This is GCC-specific but it works at least since 2.95.
 * Special care must be taken so that it does not need any uninitialized data.
 */
__attribute__((constructor))
static void _do_register(void)
{
      struct poller *p;

      if (nbpollers >= MAX_POLLERS)
            return;
      p = &pollers[nbpollers++];

      p->name = "kqueue";
      p->pref = 300;
      p->private = NULL;

      p->test = _do_test;
      p->init = _do_init;
      p->term = _do_term;
      p->poll = _do_poll;
      p->fork = _do_fork;

      p->is_set  = __fd_is_set;
      p->cond_s = p->set = __fd_set;
      p->cond_c = p->clr = __fd_clr;
      p->rem = __fd_rem;
      p->clo = __fd_clo;
}


/*
 * Local variables:
 *  c-indent-level: 8
 *  c-basic-offset: 8
 * End:
 */

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