/*  $OpenBSD: poll.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */

/*

 * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>

 * Copyright 2007-2012 Niels Provos and Nick Mathewson

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. The name of the author may not be used to endorse or promote products

 *    derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include "event2/event-config.h"

#include "evconfig-private.h"

#ifdef EVENT__HAVE_POLL

#include <sys/types.h>

#ifdef EVENT__HAVE_SYS_TIME_H

#include <sys/time.h>

#endif

#include <sys/queue.h>

#include <poll.h>

#include <signal.h>

#include <limits.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <errno.h>

#include "event-internal.h"

#include "evsignal-internal.h"

#include "log-internal.h"

#include "evmap-internal.h"

#include "event2/thread.h"

#include "evthread-internal.h"

#include "time-internal.h"

struct pollidx {

  int idxplus1;

};

struct pollop {

  int event_count;    /* Highest number alloc */

  int nfds;     /* Highest number used */

  int realloc_copy;   /* True iff we must realloc

           * event_set_copy */

  struct pollfd *event_set;

  struct pollfd *event_set_copy;

};

static void *poll_init(struct event_base *);

static int poll_add(struct event_base *, int, short old, short events, void *idx);

static int poll_del(struct event_base *, int, short old, short events, void *idx);

static int poll_dispatch(struct event_base *, struct timeval *);

static void poll_dealloc(struct event_base *);

const struct eventop pollops = {

  "poll",

  poll_init,

  poll_add,

  poll_del,

  poll_dispatch,

  poll_dealloc,

  0, /* doesn't need_reinit */

  EV_FEATURE_FDS,

  sizeof(struct pollidx),

};

static void *

poll_init(struct event_base *base)

{

  struct pollop *pollop;

  if (!(pollop = mm_calloc(1, sizeof(struct pollop))))

    return (NULL);

  evsig_init_(base);

  evutil_weakrand_seed_(&base->weakrand_seed, 0);

  return (pollop);

}

#ifdef CHECK_INVARIANTS

static void

poll_check_ok(struct pollop *pop)

{

  int i, idx;

  struct event *ev;

  for (i = 0; i < pop->fd_count; ++i) {

    idx = pop->idxplus1_by_fd[i]-1;

    if (idx < 0)

      continue;

    EVUTIL_ASSERT(pop->event_set[idx].fd == i);

  }

  for (i = 0; i < pop->nfds; ++i) {

    struct pollfd *pfd = &pop->event_set[i];

    EVUTIL_ASSERT(pop->idxplus1_by_fd[pfd->fd] == i+1);

  }

}

#else

#define poll_check_ok(pop)

#endif

static int

poll_dispatch(struct event_base *base, struct timeval *tv)

{

  int res, i, j, nfds;

  long msec = -1;

  struct pollop *pop = base->evbase;

  struct pollfd *event_set;

  poll_check_ok(pop);

  nfds = pop->nfds;

#ifndef EVENT__DISABLE_THREAD_SUPPORT

  if (base->th_base_lock) {

    /* If we're using this backend in a multithreaded setting,

     * then we need to work on a copy of event_set, so that we can

     * let other threads modify the main event_set while we're

     * polling. If we're not multithreaded, then we'll skip the

     * copy step here to save memory and time. */

    if (pop->realloc_copy) {

      struct pollfd *tmp = mm_realloc(pop->event_set_copy,

          pop->event_count * sizeof(struct pollfd));

      if (tmp == NULL) {

        event_warn("realloc");

        return -1;

      }

      pop->event_set_copy = tmp;

      pop->realloc_copy = 0;

    }

    memcpy(pop->event_set_copy, pop->event_set,

        sizeof(struct pollfd)*nfds);

    event_set = pop->event_set_copy;

  } else {

    event_set = pop->event_set;

  }

#else

  event_set = pop->event_set;

#endif

  if (tv != NULL) {

    msec = evutil_tv_to_msec_(tv);

    if (msec < 0 || msec > INT_MAX)

      msec = INT_MAX;

  }

  EVBASE_RELEASE_LOCK(base, th_base_lock);

  res = poll(event_set, nfds, msec);

  EVBASE_ACQUIRE_LOCK(base, th_base_lock);

  if (res == -1) {

    if (errno != EINTR) {

      event_warn("poll");

      return (-1);

    }

    return (0);

  }

  event_debug(("%s: poll reports %d", __func__, res));

  if (res == 0 || nfds == 0)

    return (0);

  i = evutil_weakrand_range_(&base->weakrand_seed, nfds);

  for (j = 0; j < nfds; j++) {

    int what;

    if (++i == nfds)

      i = 0;

    what = event_set[i].revents;

    if (!what)

      continue;

    res = 0;

    /* If the file gets closed notify */

    if (what & (POLLHUP|POLLERR|POLLNVAL))

      what |= POLLIN|POLLOUT;

    if (what & POLLIN)

      res |= EV_READ;

    if (what & POLLOUT)

      res |= EV_WRITE;

    if (res == 0)

      continue;

    evmap_io_active_(base, event_set[i].fd, res);

  }

  return (0);

}

static int

poll_add(struct event_base *base, int fd, short old, short events, void *idx_)

{

  struct pollop *pop = base->evbase;

  struct pollfd *pfd = NULL;

  struct pollidx *idx = idx_;

  int i;

  EVUTIL_ASSERT((events & EV_SIGNAL) == 0);

  if (!(events & (EV_READ|EV_WRITE)))

    return (0);

  poll_check_ok(pop);

  if (pop->nfds + 1 >= pop->event_count) {

    struct pollfd *tmp_event_set;

    int tmp_event_count;

    if (pop->event_count < 32)

      tmp_event_count = 32;

    else

      tmp_event_count = pop->event_count * 2;

    /* We need more file descriptors */

    tmp_event_set = mm_realloc(pop->event_set,

         tmp_event_count * sizeof(struct pollfd));

    if (tmp_event_set == NULL) {

      event_warn("realloc");

      return (-1);

    }

    pop->event_set = tmp_event_set;

    pop->event_count = tmp_event_count;

    pop->realloc_copy = 1;

  }

  i = idx->idxplus1 - 1;

  if (i >= 0) {

    pfd = &pop->event_set[i];

  } else {

    i = pop->nfds++;

    pfd = &pop->event_set[i];

    pfd->events = 0;

    pfd->fd = fd;

    idx->idxplus1 = i + 1;

  }

  pfd->revents = 0;

  if (events & EV_WRITE)

    pfd->events |= POLLOUT;

  if (events & EV_READ)

    pfd->events |= POLLIN;

  poll_check_ok(pop);

  return (0);

}

/*

 * Nothing to be done here.

 */

static int

poll_del(struct event_base *base, int fd, short old, short events, void *idx_)

{

  struct pollop *pop = base->evbase;

  struct pollfd *pfd = NULL;

  struct pollidx *idx = idx_;

  int i;

  EVUTIL_ASSERT((events & EV_SIGNAL) == 0);

  if (!(events & (EV_READ|EV_WRITE)))

    return (0);

  poll_check_ok(pop);

  i = idx->idxplus1 - 1;

  if (i < 0)

    return (-1);

  /* Do we still want to read or write? */

  pfd = &pop->event_set[i];

  if (events & EV_READ)

    pfd->events &= ~POLLIN;

  if (events & EV_WRITE)

    pfd->events &= ~POLLOUT;

  poll_check_ok(pop);

  if (pfd->events)

    /* Another event cares about that fd. */

    return (0);

  /* Okay, so we aren't interested in that fd anymore. */

  idx->idxplus1 = 0;

  --pop->nfds;

  if (i != pop->nfds) {

    /*

     * Shift the last pollfd down into the now-unoccupied

     * position.

     */

    memcpy(&pop->event_set[i], &pop->event_set[pop->nfds],

           sizeof(struct pollfd));

    idx = evmap_io_get_fdinfo_(&base->io, pop->event_set[i].fd);

    EVUTIL_ASSERT(idx);

    EVUTIL_ASSERT(idx->idxplus1 == pop->nfds + 1);

    idx->idxplus1 = i + 1;

  }

  poll_check_ok(pop);

  return (0);

}

static void

poll_dealloc(struct event_base *base)

{

  struct pollop *pop = base->evbase;

  evsig_dealloc_(base);

  if (pop->event_set)

    mm_free(pop->event_set);

  if (pop->event_set_copy)

    mm_free(pop->event_set_copy);

  memset(pop, 0, sizeof(struct pollop));

  mm_free(pop);

}

#endif /* EVENT__HAVE_POLL */