text: /* Linux epoll(2) based ae.c module
   *
   * Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   *   * Redistributions of source code must retain the above copyright notice,
   *     this list of conditions and the following disclaimer.
   *   * 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.
   *   * Neither the name of Redis nor the names of its contributors may be used
   *     to endorse or promote products derived from this software without
   *     specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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 <sys/epoll.h>
  #include <time.h>
  #include "ae.h"
  
  typedef struct aeApiState
  {
      int                 epfd;
      struct epoll_event* events;
  } aeApiState;
  
  static int aeApiCreate(aeEventLoop* eventLoop)
  {
      aeApiState* state = (aeApiState*)malloc(sizeof(aeApiState));
  
      if (!state)
          return -1;
      state->events = (struct epoll_event*)malloc(sizeof(struct epoll_event) * eventLoop->setsize);
      if (!state->events)
      {
          free(state);
          return -1;
      }
      state->epfd = epoll_create(1024); /* 1024 is just a hint for the kernel */
      if (state->epfd == -1)
      {
          free(state->events);
          free(state);
          return -1;
      }
      eventLoop->apidata = state;
      return 0;
  }
  
  static int aeApiResize(aeEventLoop* eventLoop, int setsize)
  {
      aeApiState* state = (aeApiState*)eventLoop->apidata;
  
      state->events = (struct epoll_event*)realloc(state->events, sizeof(struct epoll_event) * setsize);
      return 0;
  }
  
  static void aeApiFree(aeEventLoop* eventLoop)
  {
      aeApiState* state = (aeApiState*)eventLoop->apidata;
  
      close(state->epfd);
      free(state->events);
      free(state);
  }
  
  static int aeApiAddEvent(aeEventLoop* eventLoop, int fd, int mask)
  {
      aeApiState* state = (aeApiState*)eventLoop->apidata;
      struct epoll_event ee = { 0, 0 }; /* avoid valgrind warning */
      /* If the fd was already monitored for some event, we need a MOD
       * operation. Otherwise we need an ADD operation. */
      int op = eventLoop->events[fd].mask == AE_NONE ? EPOLL_CTL_ADD : EPOLL_CTL_MOD;
  
      ee.events = 0;
      mask |= eventLoop->events[fd].mask; /* Merge old events */
      if (mask & AE_READABLE)
          ee.events |= EPOLLIN;
      if (mask & AE_WRITABLE)
          ee.events |= EPOLLOUT;
      ee.data.fd = fd;
      if (epoll_ctl(state->epfd, op, fd, &ee) == -1)
          return -1;
      return 0;
  }
  
  static void aeApiDelEvent(aeEventLoop* eventLoop, int fd, int delmask)
  {
      aeApiState* state = (aeApiState*)eventLoop->apidata;
      struct epoll_event ee = { 0, 0 }; /* avoid valgrind warning */
      int                mask = eventLoop->events[fd].mask & (~delmask);
  
      ee.events = 0;
      if (mask & AE_READABLE)
          ee.events |= EPOLLIN;
      if (mask & AE_WRITABLE)
          ee.events |= EPOLLOUT;
      ee.data.fd = fd;
      if (mask != AE_NONE)
      {
          epoll_ctl(state->epfd, EPOLL_CTL_MOD, fd, &ee);
      }
      else
      {
          /* Note, Kernel < 2.6.9 requires a non null event pointer even for
           * EPOLL_CTL_DEL. */
          epoll_ctl(state->epfd, EPOLL_CTL_DEL, fd, &ee);
      }
  }
  
  static int aeApiPoll(aeEventLoop* eventLoop, struct timeval* tvp)
  {
      aeApiState* state = (aeApiState*)eventLoop->apidata;
      int         retval, numevents = 0;
  
      retval = epoll_wait(state->epfd, state->events, eventLoop->setsize,
          tvp ? (tvp->tv_sec * 1000 + tvp->tv_usec / 1000) : -1);
      if (retval > 0)
      {
          int j;
  
          numevents = retval;
          for (j = 0; j < numevents; j++)
          {
              int                 mask = 0;
              struct epoll_event* e = state->events + j;
  
              if (e->events & EPOLLIN)
                  mask |= AE_READABLE;
              if (e->events & EPOLLOUT)
                  mask |= AE_WRITABLE;
              if (e->events & EPOLLERR)
                  mask |= AE_WRITABLE | AE_ERR_EVENT;
              if (e->events & EPOLLHUP)
                  mask |= AE_WRITABLE | AE_ERR_EVENT;
              eventLoop->fired[j].fd = e->data.fd;
              eventLoop->fired[j].mask = mask;
          }
      }
      return numevents;
  }
  
  static char* aeApiName(void)
  {
      return (char*)"epoll";
  }
  