text: /* A simple event-driven programming library. Originally I wrote this code
   * for the Jim's event-loop (Jim is a Tcl interpreter) but later translated
   * it in form of a library for easy reuse.
   *
   * Copyright (c) 2006-2010, 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 <stdio.h>
  #include <sys/time.h>
  #include <sys/types.h>
  #include <unistd.h>
  #include <stdlib.h>
  #include <poll.h>
  #include <string.h>
  #include <time.h>
  #include <errno.h>
  
  #include "ae.h"
  #include "zmalloc.h"
  #include "config.h"
  
  /* Include the best multiplexing layer supported by this system.
   * The following should be ordered by performances, descending. */
  #ifdef HAVE_EVPORT
  #include "ae_evport.c"
  #else
      #ifdef HAVE_EPOLL
      #include "ae_epoll.c"
      #else
          #ifdef HAVE_KQUEUE
          #include "ae_kqueue.c"
          #else
          #include "ae_select.c"
          #endif
      #endif
  #endif
  
  aeEventLoop *aeCreateEventLoop(int setsize) {
      aeEventLoop *eventLoop;
      int i;
  
      if ((eventLoop = zmalloc(sizeof(*eventLoop))) == NULL) goto err;
      eventLoop->events = zmalloc(sizeof(aeFileEvent)*setsize);
      eventLoop->fired = zmalloc(sizeof(aeFiredEvent)*setsize);
      if (eventLoop->events == NULL || eventLoop->fired == NULL) goto err;
      eventLoop->setsize = setsize;
      eventLoop->lastTime = time(NULL);
      eventLoop->timeEventHead = NULL;
      eventLoop->timeEventNextId = 0;
      eventLoop->stop = 0;
      eventLoop->maxfd = -1;
      eventLoop->beforesleep = NULL;
      if (aeApiCreate(eventLoop) == -1) goto err;
      /* Events with mask == AE_NONE are not set. So let's initialize the
       * vector with it. */
      for (i = 0; i < setsize; i++)
          eventLoop->events[i].mask = AE_NONE;
      return eventLoop;
  
  err:
      if (eventLoop) {
          zfree(eventLoop->events);
          zfree(eventLoop->fired);
          zfree(eventLoop);
      }
      return NULL;
  }
  
  /* Return the current set size. */
  int aeGetSetSize(aeEventLoop *eventLoop) {
      return eventLoop->setsize;
  }
  
  /* Resize the maximum set size of the event loop.
   * If the requested set size is smaller than the current set size, but
   * there is already a file descriptor in use that is >= the requested
   * set size minus one, AE_ERR is returned and the operation is not
   * performed at all.
   *
   * Otherwise AE_OK is returned and the operation is successful. */
  int aeResizeSetSize(aeEventLoop *eventLoop, int setsize) {
      int i;
  
      if (setsize == eventLoop->setsize) return AE_OK;
      if (eventLoop->maxfd >= setsize) return AE_ERR;
      if (aeApiResize(eventLoop,setsize) == -1) return AE_ERR;
  
      eventLoop->events = zrealloc(eventLoop->events,sizeof(aeFileEvent)*setsize);
      eventLoop->fired = zrealloc(eventLoop->fired,sizeof(aeFiredEvent)*setsize);
      eventLoop->setsize = setsize;
  
      /* Make sure that if we created new slots, they are initialized with
       * an AE_NONE mask. */
      for (i = eventLoop->maxfd+1; i < setsize; i++)
          eventLoop->events[i].mask = AE_NONE;
      return AE_OK;
  }
  
  void aeDeleteEventLoop(aeEventLoop *eventLoop) {
      aeApiFree(eventLoop);
      zfree(eventLoop->events);
      zfree(eventLoop->fired);
      zfree(eventLoop);
  }
  
  void aeStop(aeEventLoop *eventLoop) {
      eventLoop->stop = 1;
  }
  
  int aeCreateFileEvent(aeEventLoop *eventLoop, int fd, int mask,
          aeFileProc *proc, void *clientData)
  {
      if (fd >= eventLoop->setsize) {
          errno = ERANGE;
          return AE_ERR;
      }
      aeFileEvent *fe = &eventLoop->events[fd];
  
      if (aeApiAddEvent(eventLoop, fd, mask) == -1)
          return AE_ERR;
      fe->mask |= mask;
      if (mask & AE_READABLE) fe->rfileProc = proc;
      if (mask & AE_WRITABLE) fe->wfileProc = proc;
      fe->clientData = clientData;
      if (fd > eventLoop->maxfd)
          eventLoop->maxfd = fd;
      return AE_OK;
  }
  
  void aeDeleteFileEvent(aeEventLoop *eventLoop, int fd, int mask)
  {
      if (fd >= eventLoop->setsize) return;
      aeFileEvent *fe = &eventLoop->events[fd];
      if (fe->mask == AE_NONE) return;
  
      aeApiDelEvent(eventLoop, fd, mask);
      fe->mask = fe->mask & (~mask);
      if (fd == eventLoop->maxfd && fe->mask == AE_NONE) {
          /* Update the max fd */
          int j;
  
          for (j = eventLoop->maxfd-1; j >= 0; j--)
              if (eventLoop->events[j].mask != AE_NONE) break;
          eventLoop->maxfd = j;
      }
  }
  
  int aeGetFileEvents(aeEventLoop *eventLoop, int fd) {
      if (fd >= eventLoop->setsize) return 0;
      aeFileEvent *fe = &eventLoop->events[fd];
  
      return fe->mask;
  }
  
  static void aeGetTime(long *seconds, long *milliseconds)
  {
      struct timeval tv;
  
      gettimeofday(&tv, NULL);
      *seconds = tv.tv_sec;
      *milliseconds = tv.tv_usec/1000;
  }
  
  static void aeAddMillisecondsToNow(long long milliseconds, long *sec, long *ms) {
      long cur_sec, cur_ms, when_sec, when_ms;
  
      aeGetTime(&cur_sec, &cur_ms);
      when_sec = cur_sec + milliseconds/1000;
      when_ms = cur_ms + milliseconds%1000;
      if (when_ms >= 1000) {
          when_sec ++;
          when_ms -= 1000;
      }
      *sec = when_sec;
      *ms = when_ms;
  }
  
  long long aeCreateTimeEvent(aeEventLoop *eventLoop, long long milliseconds,
          aeTimeProc *proc, void *clientData,
          aeEventFinalizerProc *finalizerProc)
  {
      long long id = eventLoop->timeEventNextId++;
      aeTimeEvent *te;
  
      te = zmalloc(sizeof(*te));
      if (te == NULL) return AE_ERR;
      te->id = id;
      aeAddMillisecondsToNow(milliseconds,&te->when_sec,&te->when_ms);
      te->timeProc = proc;
      te->finalizerProc = finalizerProc;
      te->clientData = clientData;
      te->next = eventLoop->timeEventHead;
      eventLoop->timeEventHead = te;
      return id;
  }
  
  int aeDeleteTimeEvent(aeEventLoop *eventLoop, long long id)
  {
      aeTimeEvent *te, *prev = NULL;
  
      te = eventLoop->timeEventHead;
      while(te) {
          if (te->id == id) {
              if (prev == NULL)
                  eventLoop->timeEventHead = te->next;
              else
                  prev->next = te->next;
              if (te->finalizerProc)
                  te->finalizerProc(eventLoop, te->clientData);
              zfree(te);
              return AE_OK;
          }
          prev = te;
          te = te->next;
      }
      return AE_ERR; /* NO event with the specified ID found */
  }
  
  /* Search the first timer to fire.
   * This operation is useful to know how many time the select can be
   * put in sleep without to delay any event.
   * If there are no timers NULL is returned.
   *
   * Note that's O(N) since time events are unsorted.
   * Possible optimizations (not needed by Redis so far, but...):
   * 1) Insert the event in order, so that the nearest is just the head.
   *    Much better but still insertion or deletion of timers is O(N).
   * 2) Use a skiplist to have this operation as O(1) and insertion as O(log(N)).
   */
  static aeTimeEvent *aeSearchNearestTimer(aeEventLoop *eventLoop)
  {
      aeTimeEvent *te = eventLoop->timeEventHead;
      aeTimeEvent *nearest = NULL;
  
      while(te) {
          if (!nearest || te->when_sec < nearest->when_sec ||
                  (te->when_sec == nearest->when_sec &&
                   te->when_ms < nearest->when_ms))
              nearest = te;
          te = te->next;
      }
      return nearest;
  }
  
  /* Process time events */
  static int processTimeEvents(aeEventLoop *eventLoop) {
      int processed = 0;
      aeTimeEvent *te;
      long long maxId;
      time_t now = time(NULL);
  
      /* If the system clock is moved to the future, and then set back to the
       * right value, time events may be delayed in a random way. Often this
       * means that scheduled operations will not be performed soon enough.
       *
       * Here we try to detect system clock skews, and force all the time
       * events to be processed ASAP when this happens: the idea is that
       * processing events earlier is less dangerous than delaying them
       * indefinitely, and practice suggests it is. */
      if (now < eventLoop->lastTime) {
          te = eventLoop->timeEventHead;
          while(te) {
              te->when_sec = 0;
              te = te->next;
          }
      }
      eventLoop->lastTime = now;
  
      te = eventLoop->timeEventHead;
      maxId = eventLoop->timeEventNextId-1;
      while(te) {
          long now_sec, now_ms;
          long long id;
  
          if (te->id > maxId) {
              te = te->next;
              continue;
          }
          aeGetTime(&now_sec, &now_ms);
          if (now_sec > te->when_sec ||
              (now_sec == te->when_sec && now_ms >= te->when_ms))
          {
              int retval;
  
              id = te->id;
              retval = te->timeProc(eventLoop, id, te->clientData);
              processed++;
              /* After an event is processed our time event list may
               * no longer be the same, so we restart from head.
               * Still we make sure to don't process events registered
               * by event handlers itself in order to don't loop forever.
               * To do so we saved the max ID we want to handle.
               *
               * FUTURE OPTIMIZATIONS:
               * Note that this is NOT great algorithmically. Redis uses
               * a single time event so it's not a problem but the right
               * way to do this is to add the new elements on head, and
               * to flag deleted elements in a special way for later
               * deletion (putting references to the nodes to delete into
               * another linked list). */
              if (retval != AE_NOMORE) {
                  aeAddMillisecondsToNow(retval,&te->when_sec,&te->when_ms);
              } else {
                  aeDeleteTimeEvent(eventLoop, id);
              }
              te = eventLoop->timeEventHead;
          } else {
              te = te->next;
          }
      }
      return processed;
  }
  
  /* Process every pending time event, then every pending file event
   * (that may be registered by time event callbacks just processed).
   * Without special flags the function sleeps until some file event
   * fires, or when the next time event occurs (if any).
   *
   * If flags is 0, the function does nothing and returns.
   * if flags has AE_ALL_EVENTS set, all the kind of events are processed.
   * if flags has AE_FILE_EVENTS set, file events are processed.
   * if flags has AE_TIME_EVENTS set, time events are processed.
   * if flags has AE_DONT_WAIT set the function returns ASAP until all
   * the events that's possible to process without to wait are processed.
   *
   * The function returns the number of events processed. */
  int aeProcessEvents(aeEventLoop *eventLoop, int flags)
  {
      int processed = 0, numevents;
  
      /* Nothing to do? return ASAP */
      if (!(flags & AE_TIME_EVENTS) && !(flags & AE_FILE_EVENTS)) return 0;
  
      /* Note that we want call select() even if there are no
       * file events to process as long as we want to process time
       * events, in order to sleep until the next time event is ready
       * to fire. */
      if (eventLoop->maxfd != -1 ||
          ((flags & AE_TIME_EVENTS) && !(flags & AE_DONT_WAIT))) {
          int j;
          aeTimeEvent *shortest = NULL;
          struct timeval tv, *tvp;
  
          if (flags & AE_TIME_EVENTS && !(flags & AE_DONT_WAIT))
              shortest = aeSearchNearestTimer(eventLoop);
          if (shortest) {
              long now_sec, now_ms;
  
              /* Calculate the time missing for the nearest
               * timer to fire. */
              aeGetTime(&now_sec, &now_ms);
              tvp = &tv;
              tvp->tv_sec = shortest->when_sec - now_sec;
              if (shortest->when_ms < now_ms) {
                  tvp->tv_usec = ((shortest->when_ms+1000) - now_ms)*1000;
                  tvp->tv_sec --;
              } else {
                  tvp->tv_usec = (shortest->when_ms - now_ms)*1000;
              }
              if (tvp->tv_sec < 0) tvp->tv_sec = 0;
              if (tvp->tv_usec < 0) tvp->tv_usec = 0;
          } else {
              /* If we have to check for events but need to return
               * ASAP because of AE_DONT_WAIT we need to set the timeout
               * to zero */
              if (flags & AE_DONT_WAIT) {
                  tv.tv_sec = tv.tv_usec = 0;
                  tvp = &tv;
              } else {
                  /* Otherwise we can block */
                  tvp = NULL; /* wait forever */
              }
          }
  
          numevents = aeApiPoll(eventLoop, tvp);
          for (j = 0; j < numevents; j++) {
              aeFileEvent *fe = &eventLoop->events[eventLoop->fired[j].fd];
              int mask = eventLoop->fired[j].mask;
              int fd = eventLoop->fired[j].fd;
              int rfired = 0;
  
              /* note the fe->mask & mask & ... code: maybe an already processed
               * event removed an element that fired and we still didn't
               * processed, so we check if the event is still valid. */
              if (fe->mask & mask & AE_READABLE) {
                  rfired = 1;
                  fe->rfileProc(eventLoop,fd,fe->clientData,mask);
              }
              if (fe->mask & mask & AE_WRITABLE) {
                  if (!rfired || fe->wfileProc != fe->rfileProc)
                      fe->wfileProc(eventLoop,fd,fe->clientData,mask);
              }
              processed++;
          }
      }
      /* Check time events */
      if (flags & AE_TIME_EVENTS)
          processed += processTimeEvents(eventLoop);
  
      return processed; /* return the number of processed file/time events */
  }
  
  /* Wait for milliseconds until the given file descriptor becomes
   * writable/readable/exception */
  int aeWait(int fd, int mask, long long milliseconds) {
      struct pollfd pfd;
      int retmask = 0, retval;
  
      memset(&pfd, 0, sizeof(pfd));
      pfd.fd = fd;
      if (mask & AE_READABLE) pfd.events |= POLLIN;
      if (mask & AE_WRITABLE) pfd.events |= POLLOUT;
  
      if ((retval = poll(&pfd, 1, milliseconds))== 1) {
          if (pfd.revents & POLLIN) retmask |= AE_READABLE;
          if (pfd.revents & POLLOUT) retmask |= AE_WRITABLE;
  	if (pfd.revents & POLLERR) retmask |= AE_WRITABLE;
          if (pfd.revents & POLLHUP) retmask |= AE_WRITABLE;
          return retmask;
      } else {
          return retval;
      }
  }
  
  void aeMain(aeEventLoop *eventLoop) {
      eventLoop->stop = 0;
      while (!eventLoop->stop) {
          if (eventLoop->beforesleep != NULL)
              eventLoop->beforesleep(eventLoop);
          aeProcessEvents(eventLoop, AE_ALL_EVENTS);
      }
  }
  
  char *aeGetApiName(void) {
      return aeApiName();
  }
  
  void aeSetBeforeSleepProc(aeEventLoop *eventLoop, aeBeforeSleepProc *beforesleep) {
      eventLoop->beforesleep = beforesleep;
  }
  