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libuv/src/unix/linux-core.c  view on Meta::CPAN

static int read_models(unsigned int numcpus, uv_cpu_info_t* ci);
static int read_times(FILE* statfile_fp,
                      unsigned int numcpus,
                      uv_cpu_info_t* ci);
static void read_speeds(unsigned int numcpus, uv_cpu_info_t* ci);
static unsigned long read_cpufreq(unsigned int cpunum);


int uv__platform_loop_init(uv_loop_t* loop) {
  int fd;

  fd = epoll_create1(EPOLL_CLOEXEC);

  /* epoll_create1() can fail either because it's not implemented (old kernel)
   * or because it doesn't understand the EPOLL_CLOEXEC flag.
   */
  if (fd == -1 && (errno == ENOSYS || errno == EINVAL)) {
    fd = epoll_create(256);

    if (fd != -1)
      uv__cloexec(fd, 1);
  }

  loop->backend_fd = fd;
  loop->inotify_fd = -1;
  loop->inotify_watchers = NULL;

  if (fd == -1)
    return UV__ERR(errno);

  return 0;
}


int uv__io_fork(uv_loop_t* loop) {
  int err;
  void* old_watchers;

  old_watchers = loop->inotify_watchers;

  uv__close(loop->backend_fd);
  loop->backend_fd = -1;
  uv__platform_loop_delete(loop);

  err = uv__platform_loop_init(loop);
  if (err)
    return err;

  return uv__inotify_fork(loop, old_watchers);
}


void uv__platform_loop_delete(uv_loop_t* loop) {
  if (loop->inotify_fd == -1) return;
  uv__io_stop(loop, &loop->inotify_read_watcher, POLLIN);
  uv__close(loop->inotify_fd);
  loop->inotify_fd = -1;
}


void uv__platform_invalidate_fd(uv_loop_t* loop, int fd) {
  struct epoll_event* events;
  struct epoll_event dummy;
  uintptr_t i;
  uintptr_t nfds;

  assert(loop->watchers != NULL);
  assert(fd >= 0);

  events = (struct epoll_event*) loop->watchers[loop->nwatchers];
  nfds = (uintptr_t) loop->watchers[loop->nwatchers + 1];
  if (events != NULL)
    /* Invalidate events with same file descriptor */
    for (i = 0; i < nfds; i++)
      if (events[i].data.fd == fd)
        events[i].data.fd = -1;

  /* Remove the file descriptor from the epoll.
   * This avoids a problem where the same file description remains open
   * in another process, causing repeated junk epoll events.
   *
   * We pass in a dummy epoll_event, to work around a bug in old kernels.
   */
  if (loop->backend_fd >= 0) {
    /* Work around a bug in kernels 3.10 to 3.19 where passing a struct that
     * has the EPOLLWAKEUP flag set generates spurious audit syslog warnings.
     */
    memset(&dummy, 0, sizeof(dummy));
    epoll_ctl(loop->backend_fd, EPOLL_CTL_DEL, fd, &dummy);
  }
}


int uv__io_check_fd(uv_loop_t* loop, int fd) {
  struct epoll_event e;
  int rc;

  memset(&e, 0, sizeof(e));
  e.events = POLLIN;
  e.data.fd = -1;

  rc = 0;
  if (epoll_ctl(loop->backend_fd, EPOLL_CTL_ADD, fd, &e))
    if (errno != EEXIST)
      rc = UV__ERR(errno);

  if (rc == 0)
    if (epoll_ctl(loop->backend_fd, EPOLL_CTL_DEL, fd, &e))
      abort();

  return rc;
}


void uv__io_poll(uv_loop_t* loop, int timeout) {
  /* A bug in kernels < 2.6.37 makes timeouts larger than ~30 minutes
   * effectively infinite on 32 bits architectures.  To avoid blocking
   * indefinitely, we cap the timeout and poll again if necessary.
   *
   * Note that "30 minutes" is a simplification because it depends on
   * the value of CONFIG_HZ.  The magic constant assumes CONFIG_HZ=1200,
   * that being the largest value I have seen in the wild (and only once.)
   */
  static const int max_safe_timeout = 1789569;
  struct epoll_event events[1024];
  struct epoll_event* pe;
  struct epoll_event e;
  int real_timeout;
  QUEUE* q;
  uv__io_t* w;
  sigset_t sigset;
  sigset_t* psigset;
  uint64_t base;

libuv/src/unix/linux-core.c  view on Meta::CPAN

  assert(timeout >= -1);
  base = loop->time;
  count = 48; /* Benchmarks suggest this gives the best throughput. */
  real_timeout = timeout;

  for (;;) {
    /* See the comment for max_safe_timeout for an explanation of why
     * this is necessary.  Executive summary: kernel bug workaround.
     */
    if (sizeof(int32_t) == sizeof(long) && timeout >= max_safe_timeout)
      timeout = max_safe_timeout;

    nfds = epoll_pwait(loop->backend_fd,
                       events,
                       ARRAY_SIZE(events),
                       timeout,
                       psigset);

    /* Update loop->time unconditionally. It's tempting to skip the update when
     * timeout == 0 (i.e. non-blocking poll) but there is no guarantee that the
     * operating system didn't reschedule our process while in the syscall.
     */
    SAVE_ERRNO(uv__update_time(loop));

    if (nfds == 0) {
      assert(timeout != -1);

      if (timeout == 0)
        return;

      /* We may have been inside the system call for longer than |timeout|
       * milliseconds so we need to update the timestamp to avoid drift.
       */
      goto update_timeout;
    }

    if (nfds == -1) {
      if (errno != EINTR)
        abort();

      if (timeout == -1)
        continue;

      if (timeout == 0)
        return;

      /* Interrupted by a signal. Update timeout and poll again. */
      goto update_timeout;
    }

    have_signals = 0;
    nevents = 0;

    assert(loop->watchers != NULL);
    loop->watchers[loop->nwatchers] = (void*) events;
    loop->watchers[loop->nwatchers + 1] = (void*) (uintptr_t) nfds;
    for (i = 0; i < nfds; i++) {
      pe = events + i;
      fd = pe->data.fd;

      /* Skip invalidated events, see uv__platform_invalidate_fd */
      if (fd == -1)
        continue;

      assert(fd >= 0);
      assert((unsigned) fd < loop->nwatchers);

      w = loop->watchers[fd];

      if (w == NULL) {
        /* File descriptor that we've stopped watching, disarm it.
         *
         * Ignore all errors because we may be racing with another thread
         * when the file descriptor is closed.
         */
        epoll_ctl(loop->backend_fd, EPOLL_CTL_DEL, fd, pe);
        continue;
      }

      /* Give users only events they're interested in. Prevents spurious
       * callbacks when previous callback invocation in this loop has stopped
       * the current watcher. Also, filters out events that users has not
       * requested us to watch.
       */
      pe->events &= w->pevents | POLLERR | POLLHUP;

      /* Work around an epoll quirk where it sometimes reports just the
       * EPOLLERR or EPOLLHUP event.  In order to force the event loop to
       * move forward, we merge in the read/write events that the watcher
       * is interested in; uv__read() and uv__write() will then deal with
       * the error or hangup in the usual fashion.
       *
       * Note to self: happens when epoll reports EPOLLIN|EPOLLHUP, the user
       * reads the available data, calls uv_read_stop(), then sometime later
       * calls uv_read_start() again.  By then, libuv has forgotten about the
       * hangup and the kernel won't report EPOLLIN again because there's
       * nothing left to read.  If anything, libuv is to blame here.  The
       * current hack is just a quick bandaid; to properly fix it, libuv
       * needs to remember the error/hangup event.  We should get that for
       * free when we switch over to edge-triggered I/O.
       */
      if (pe->events == POLLERR || pe->events == POLLHUP)
        pe->events |=
          w->pevents & (POLLIN | POLLOUT | UV__POLLRDHUP | UV__POLLPRI);

      if (pe->events != 0) {
        /* Run signal watchers last.  This also affects child process watchers
         * because those are implemented in terms of signal watchers.
         */
        if (w == &loop->signal_io_watcher)
          have_signals = 1;
        else
          w->cb(loop, w, pe->events);

        nevents++;
      }
    }

    if (have_signals != 0)
      loop->signal_io_watcher.cb(loop, &loop->signal_io_watcher, POLLIN);