def select()

in qpid/compat.py [0:0]

• 42 lines of code
• 13 McCabe index (conditional complexity)

  def select(rlist, wlist, xlist, timeout=None):
    fd_count = 0
    rset = set(rlist)
    wset = set(wlist)
    xset = set(xlist)
    if timeout:
      # select expects seconds, poll milliseconds
      timeout = float(timeout) * 1000
    poller = _select_mod.poll()

    rwset = rset.intersection(wset)
    for rw in rwset:
      poller.register(rw, (_select_mod.POLLIN | _select_mod.POLLOUT))
      fd_count += 1
    for ro in rset.difference(rwset):
      poller.register(ro, _select_mod.POLLIN)
      fd_count += 1
    for wo in wset.difference(rwset):
      poller.register(wo, _select_mod.POLLOUT)
      fd_count += 1
    for x in xset:
      poller.register(x, _select_mod.POLLPRI)
      fd_count += 1

    # select returns the objects passed in, but poll gives us back only the
    # integer fds.  Maintain a map to get back:
    fd_map = {}
    for o in rset | wset | xset:
      if hasattr(o, "fileno"):
        fd_map[o.fileno()] = o

    log.debug("poll(%d fds, timeout=%s)", fd_count, timeout)
    active = poller.poll(timeout)
    log.debug("poll() returned %s fds", len(active))

    rfds = []
    wfds = []
    xfds = []
    # set the error conditions so we do a read(), which will report the error
    rflags = (_select_mod.POLLIN | _select_mod.POLLERR | _select_mod.POLLHUP)
    for fds, flags in active:
      if fds in fd_map:
        fds = fd_map[fds]
      if (flags & rflags):
        rfds.append(fds)
      if (flags & _select_mod.POLLOUT):
        wfds.append(fds)
      if (flags & _select_mod.POLLPRI):
        xfds.append(fds)
    return (rfds, wfds, xfds)