libev

void
ev_run (EV_P_ int flags)
{
  assert (("libev: ev_loop recursion during release detected", loop_done != EVBREAK_RECURSE));

  loop_done = EVBREAK_CANCEL;

  EV_INVOKE_PENDING; /* in case we recurse, ensure ordering stays nice and clean */

  do
    {
      if (expect_false (loop_done))
        break;

      /* update fd-related kernel structures */
      fd_reify (EV_A);

      /* calculate blocking time */
      {
        ev_tstamp waittime  = 0.;
        ev_tstamp sleeptime = 0.;

        /* remember old timestamp for io_blocktime calculation */
        ev_tstamp prev_mn_now = mn_now;

        /* update time to cancel out callback processing overhead */
        time_update (EV_A_ 1e100);

        if (expect_true (!(flags & EVRUN_NOWAIT || idleall || !activecnt)))
          {
            waittime = MAX_BLOCKTIME;

            if (timercnt)
              {
                ev_tstamp to = ANHE_at (timers [HEAP0]) - mn_now + backend_fudge;
                if (waittime > to) waittime = to;
              }

            /* don't let timeouts decrease the waittime below timeout_blocktime */
            if (expect_false (waittime < timeout_blocktime))
              waittime = timeout_blocktime;

            /* extra check because io_blocktime is commonly 0 */
            if (expect_false (io_blocktime))
              {
                sleeptime = io_blocktime - (mn_now - prev_mn_now);

                if (sleeptime > waittime - backend_fudge)
                  sleeptime = waittime - backend_fudge;

                if (expect_true (sleeptime > 0.))
                  {
                    ev_sleep (sleeptime);
                    waittime -= sleeptime;
                  }
              }
          }

        assert ((loop_done = EVBREAK_RECURSE, 1)); /* assert for side effect */
        backend_poll (EV_A_ waittime);
        assert ((loop_done = EVBREAK_CANCEL, 1)); /* assert for side effect */

        /* update ev_rt_now, do magic */
        time_update (EV_A_ waittime + sleeptime);
      }

      /* queue pending timers and reschedule them */
      timers_reify (EV_A); /* relative timers called last */

      EV_INVOKE_PENDING;
    }
  while (expect_true (
    activecnt
    && !loop_done
    && !(flags & (EVRUN_ONCE | EVRUN_NOWAIT))
  ));

  if (loop_done == EVBREAK_ONE)
    loop_done = EVBREAK_CANCEL;
}

inline_size void
fd_reify (EV_P)
{
  int i;
  for (i = 0; i < fdchangecnt; ++i)
    {
      int fd = fdchanges [i];
      ANFD *anfd = anfds + fd;
      ev_io *w;

      unsigned char o_events = anfd->events;
      unsigned char o_reify  = anfd->reify;

      anfd->reify  = 0;

      /*if (expect_true (o_reify & EV_ANFD_REIFY)) probably a deoptimisation */
        {
          anfd->events = 0;

          for (w = (ev_io *)anfd->head; w; w = (ev_io *)((WL)w)->next)
            anfd->events |= (unsigned char)w->events;

          if (o_events != anfd->events)
            o_reify = EV__IOFDSET; /* actually |= */
        }

      if (o_reify & EV__IOFDSET)
        backend_modify (EV_A_ fd, o_events, anfd->events);
    }

  fdchangecnt = 0;
}

void noinline
ev_io_start (EV_P_ ev_io *w)
{
  int fd = w->fd;

  if (expect_false (ev_is_active (w)))
    return;

  assert (("libev: ev_io_start called with negative fd", fd >= 0));
  assert (("libev: ev_io_start called with illegal event mask", !(w->events & ~(EV__IOFDSET | EV_READ | EV_WRITE))));

  EV_FREQUENT_CHECK;

  ev_start (EV_A_ (W)w, 1);
  array_needsize (ANFD, anfds, anfdmax, fd + 1, array_init_zero);
  wlist_add (&anfds[fd].head, (WL)w);

  fd_change (EV_A_ fd, w->events & EV__IOFDSET | EV_ANFD_REIFY);
  w->events &= ~EV__IOFDSET;

  EV_FREQUENT_CHECK;
}

inline_size void
fd_change (EV_P_ int fd, int flags)
{
  unsigned char reify = anfds [fd].reify;
  anfds [fd].reify |= flags;

  if (expect_true (!reify))
    {
      ++fdchangecnt;
      array_needsize (int, fdchanges, fdchangemax, fdchangecnt, EMPTY2);
      fdchanges [fdchangecnt - 1] = fd;
    }
}

inline_speed void
fd_event_nocheck (EV_P_ int fd, int revents)
{
  ANFD *anfd = anfds + fd;
  ev_io *w;

  for (w = (ev_io *)anfd->head; w; w = (ev_io *)((WL)w)->next)
    {
      int ev = w->events & revents;

      if (ev)
        ev_feed_event (EV_A_ (W)w, ev);
    }
}
void noinline
ev_feed_event (EV_P_ void *w, int revents)
{
  W w_ = (W)w;
  int pri = ABSPRI (w_);

  if (expect_false (w_->pending))
    pendings [pri][w_->pending - 1].events |= revents;
  else
    {
      w_->pending = ++pendingcnt [pri];
      array_needsize (ANPENDING, pendings [pri], pendingmax [pri], w_->pending, EMPTY2);
      // set the watcher and revents.
      pendings [pri][w_->pending - 1].w      = w_;
      pendings [pri][w_->pending - 1].events = revents;
    }
}

inline_size void
timers_reify (EV_P)
{
  EV_FREQUENT_CHECK;

  if (timercnt && ANHE_at (timers [HEAP0]) < mn_now)
    {
      do
        {
          ev_timer *w = (ev_timer *)ANHE_w (timers [HEAP0]);

          /*assert (("libev: inactive timer on timer heap detected", ev_is_active (w)));*/

          /* first reschedule or stop timer */
          if (w->repeat)
            {
              ev_at (w) += w->repeat;
              if (ev_at (w) < mn_now)
                ev_at (w) = mn_now;

              assert (("libev: negative ev_timer repeat value found while processing timers", w->repeat > 0.));

              ANHE_at_cache (timers [HEAP0]);
              downheap (timers, timercnt, HEAP0);
            }
          else
            ev_timer_stop (EV_A_ w); /* nonrepeating: stop timer */

          EV_FREQUENT_CHECK;
          feed_reverse (EV_A_ (W)w);
        }
      while (timercnt && ANHE_at (timers [HEAP0]) < mn_now);

      feed_reverse_done (EV_A_ EV_TIMER);
    }
}

void noinline
ev_invoke_pending (EV_P)
{
  int pri;

  for (pri = NUMPRI; pri--; )
    while (pendingcnt [pri])
      {
        ANPENDING *p = pendings [pri] + --pendingcnt [pri];

        p->w->pending = 0;
        EV_CB_INVOKE (p->w, p->events);
        EV_FREQUENT_CHECK;
      }
}

#ifndef _COMMON_H_
#define _COMMON_H_

#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <strings.h>
#include <cstdlib>
#include <cstdio>
#include <cstddef>
#include <string>

namespace common{

#define D(exp,fmt,...) do {                     \
        if(!(exp)){                             \
            fprintf(stderr,fmt,##__VA_ARGS__);  \
            abort();                            \
        }                                       \
    }while(0)

static void setnonblock(int fd){
    fcntl(fd,F_SETFL,fcntl(fd,F_GETFL) | O_NONBLOCK);
}
static void setreuseaddr(int fd){
    int ok=1;
    setsockopt(fd,SOL_SOCKET,SO_REUSEADDR,&ok,sizeof(ok));
}

static void setaddress(const char* ip,int port,struct sockaddr_in* addr){
    bzero(addr,sizeof(*addr));
    addr->sin_family=AF_INET;
    inet_pton(AF_INET,ip,&(addr->sin_addr));
    addr->sin_port=htons(port);
}

static std::string address_to_string(struct sockaddr_in* addr){
    char ip[128];
    inet_ntop(AF_INET,&(addr->sin_addr),ip,sizeof(ip));
    char port[32];
    snprintf(port,sizeof(port),"%d",ntohs(addr->sin_port));
    std::string r;
    r=r+"("+ip+":"+port+")";
    return r;
}

static int new_tcp_server(int port){
    int fd=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
    D(fd>0,"socket failed(%m)\n");
    setnonblock(fd);
    setreuseaddr(fd);
    sockaddr_in addr;
    setaddress("0.0.0.0",port,&addr);
    bind(fd,(struct sockaddr*)&addr,sizeof(addr));
    listen(fd,64); // backlog = 64
    return fd;
}

static int new_tcp_client(const char* ip,int port){
    int fd=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
    setnonblock(fd);
    sockaddr_in addr;
    setaddress(ip,port,&addr);
    connect(fd,(struct sockaddr*)(&addr),sizeof(addr));
    return fd;
}

}; // namespace common

#endif // _COMMON_H_

#include "ev.h"
#include "common.h"

static void do_connected(struct ev_loop* reactor,ev_io* w,int events){
    close(w->fd);
    ev_break(reactor,EVBREAK_ALL);
}

int main(){
    struct ev_loop* reactor=ev_loop_new(EVFLAG_AUTO);
    int fd=common::new_tcp_client("127.0.0.1",34567);
    ev_io io;
    ev_io_init(&io,&do_connected,fd,EV_WRITE);
    ev_io_start(reactor,&io);
    ev_run(reactor,0);
    close(fd);
    ev_loop_destroy(reactor);
    return 0;
}

#include "ev.h"
#include "common.h"

static void do_accept(struct ev_loop* reactor,ev_io* w,int events){
    struct sockaddr_in addr;
    socklen_t addr_size=sizeof(addr);
    int conn=accept(w->fd,(struct sockaddr*)&addr,&addr_size);
    std::string r=common::address_to_string(&addr);
    fprintf(stderr,"accept %s\n",r.c_str());
    close(conn);
}

int main(){
    struct ev_loop* reactor=ev_loop_new(EVFLAG_AUTO);
    int fd=common::new_tcp_server(34567);
    ev_io w;
    ev_io_init(&w,do_accept,fd,EV_READ);
    ev_io_start(reactor,&w);
    ev_run(reactor,0);
    close(fd);
    ev_loop_destroy(reactor);
}