Windows: Use 32-bit distribution of python

1 files changed, 709 insertions, 0 deletions

diff --git a/python/gevent/_ffi/loop.py b/python/gevent/_ffi/loop.py
new file mode 100644
index 0000000..efe4462
--- /dev/null
+++ b/python/gevent/_ffi/loop.py
@@ -0,0 +1,709 @@
+"""
+Basic loop implementation for ffi-based cores.
+"""
+# pylint: disable=too-many-lines, protected-access, redefined-outer-name, not-callable
+from __future__ import absolute_import, print_function
+
+from collections import deque
+import sys
+import os
+import traceback
+
+from gevent._ffi import _dbg
+from gevent._ffi import GEVENT_DEBUG_LEVEL
+from gevent._ffi import TRACE
+from gevent._ffi.callback import callback
+from gevent._compat import PYPY
+
+from gevent import getswitchinterval
+
+__all__ = [
+    'AbstractLoop',
+    'assign_standard_callbacks',
+]
+
+
+class _EVENTSType(object):
+    def __repr__(self):
+        return 'gevent.core.EVENTS'
+
+EVENTS = GEVENT_CORE_EVENTS = _EVENTSType()
+
+
+#####
+## Note on CFFI objects, callbacks and the lifecycle of watcher objects
+#
+# Each subclass of `watcher` allocates a C structure of the
+# appropriate type e.g., struct gevent_ev_io and holds this pointer in
+# its `_gwatcher` attribute. When that watcher instance is garbage
+# collected, then the C structure is also freed. The C structure is
+# passed to libev from the watcher's start() method and then to the
+# appropriate C callback function, e.g., _gevent_ev_io_callback, which
+# passes it back to python's _python_callback where we need the
+# watcher instance. Therefore, as long as that callback is active (the
+# watcher is started), the watcher instance must not be allowed to get
+# GC'd---any access at the C level or even the FFI level to the freed
+# memory could crash the process.
+#
+# However, the typical idiom calls for writing something like this:
+#  loop.io(fd, python_cb).start()
+# thus forgetting the newly created watcher subclass and allowing it to be immediately
+# GC'd. To combat this, when the watcher is started, it places itself into the loop's
+# `_keepaliveset`, and it only removes itself when the watcher's `stop()` method is called.
+# Often, this is the *only* reference keeping the watcher object, and hence its C structure,
+# alive.
+#
+# This is slightly complicated by the fact that the python-level
+# callback, called from the C callback, could choose to manually stop
+# the watcher. When we return to the C level callback, we now have an
+# invalid pointer, and attempting to pass it back to Python (e.g., to
+# handle an error) could crash. Hence, _python_callback,
+# _gevent_io_callback, and _python_handle_error cooperate to make sure
+# that the watcher instance stays in the loops `_keepaliveset` while
+# the C code could be running---and if it gets removed, to not call back
+# to Python again.
+# See also https://github.com/gevent/gevent/issues/676
+####
+class AbstractCallbacks(object):
+
+
+    def __init__(self, ffi):
+        self.ffi = ffi
+        self.callbacks = []
+        if GEVENT_DEBUG_LEVEL < TRACE:
+            self.from_handle = ffi.from_handle
+
+    def from_handle(self, handle): # pylint:disable=method-hidden
+        x = self.ffi.from_handle(handle)
+        return x
+
+    def python_callback(self, handle, revents):
+        """
+        Returns an integer having one of three values:
+
+        - -1
+          An exception occurred during the callback and you must call
+          :func:`_python_handle_error` to deal with it. The Python watcher
+          object will have the exception tuple saved in ``_exc_info``.
+        - 1
+          Everything went according to plan. You should check to see if the libev
+          watcher is still active, and call :func:`python_stop` if it is not. This will
+          clean up the memory. Finding the watcher still active at the event loop level,
+          but not having stopped itself at the gevent level is a buggy scenario and
+          shouldn't happen.
+        - 2
+          Everything went according to plan, but the watcher has already
+          been stopped. Its memory may no longer be valid.
+
+        This function should never return 0, as that's the default value that
+        Python exceptions will produce.
+        """
+        #print("Running callback", handle)
+        orig_ffi_watcher = None
+        try:
+            # Even dereferencing the handle needs to be inside the try/except;
+            # if we don't return normally (e.g., a signal) then we wind up going
+            # to the 'onerror' handler (unhandled_onerror), which
+            # is not what we want; that can permanently wedge the loop depending
+            # on which callback was executing.
+            # XXX: See comments in that function. We may be able to restart and do better?
+            if not handle:
+                # Hmm, a NULL handle. That's not supposed to happen.
+                # We can easily get into a loop if we deref it and allow that
+                # to raise.
+                _dbg("python_callback got null handle")
+                return 1
+            the_watcher = self.from_handle(handle)
+            orig_ffi_watcher = the_watcher._watcher
+            args = the_watcher.args
+            if args is None:
+                # Legacy behaviour from corecext: convert None into ()
+                # See test__core_watcher.py
+                args = _NOARGS
+            if args and args[0] == GEVENT_CORE_EVENTS:
+                args = (revents, ) + args[1:]
+            #print("Calling function", the_watcher.callback, args)
+            the_watcher.callback(*args)
+        except: # pylint:disable=bare-except
+            _dbg("Got exception servicing watcher with handle", handle, sys.exc_info())
+            # It's possible for ``the_watcher`` to be undefined (UnboundLocalError)
+            # if we threw an exception (signal) on the line that created that variable.
+            # This is typically the case with a signal under libuv
+            try:
+                the_watcher
+            except UnboundLocalError:
+                the_watcher = self.from_handle(handle)
+            the_watcher._exc_info = sys.exc_info()
+            # Depending on when the exception happened, the watcher
+            # may or may not have been stopped. We need to make sure its
+            # memory stays valid so we can stop it at the ev level if needed.
+            the_watcher.loop._keepaliveset.add(the_watcher)
+            return -1
+        else:
+            if (the_watcher.loop is not None
+                    and the_watcher in the_watcher.loop._keepaliveset
+                    and the_watcher._watcher is orig_ffi_watcher):
+                # It didn't stop itself, *and* it didn't stop itself, reset
+                # its watcher, and start itself again. libuv's io watchers MAY
+                # do that.
+                # The normal, expected scenario when we find the watcher still
+                # in the keepaliveset is that it is still active at the event loop
+                # level, so we don't expect that python_stop gets called.
+                #_dbg("The watcher has not stopped itself, possibly still active", the_watcher)
+                return 1
+            return 2 # it stopped itself
+
+    def python_handle_error(self, handle, _revents):
+        _dbg("Handling error for handle", handle)
+        if not handle:
+            return
+        try:
+            watcher = self.from_handle(handle)
+            exc_info = watcher._exc_info
+            del watcher._exc_info
+            # In the past, we passed the ``watcher`` itself as the context,
+            # which typically meant that the Hub would just print
+            # the exception. This is a problem because sometimes we can't
+            # detect signals until late in ``python_callback``; specifically,
+            # test_selectors.py:DefaultSelectorTest.test_select_interrupt_exc
+            # installs a SIGALRM handler that raises an exception. That exception can happen
+            # before we enter ``python_callback`` or at any point within it because of the way
+            # libuv swallows signals. By passing None, we get the exception prapagated into
+            # the main greenlet (which is probably *also* not what we always want, but
+            # I see no way to distinguish the cases).
+            watcher.loop.handle_error(None, *exc_info)
+        finally:
+            # XXX Since we're here on an error condition, and we
+            # made sure that the watcher object was put in loop._keepaliveset,
+            # what about not stopping the watcher? Looks like a possible
+            # memory leak?
+            # XXX: This used to do "if revents & (libev.EV_READ | libev.EV_WRITE)"
+            # before stopping. Why?
+            try:
+                watcher.stop()
+            except: # pylint:disable=bare-except
+                watcher.loop.handle_error(watcher, *sys.exc_info())
+            return # pylint:disable=lost-exception
+
+    def unhandled_onerror(self, t, v, tb):
+        # This is supposed to be called for signals, etc.
+        # This is the onerror= value for CFFI.
+        # If we return None, C will get a value of 0/NULL;
+        # if we raise, CFFI will print the exception and then
+        # return 0/NULL; (unless error= was configured)
+        # If things go as planned, we return the value that asks
+        # C to call back and check on if the watcher needs to be closed or
+        # not.
+
+        # XXX: TODO: Could this cause events to be lost? Maybe we need to return
+        # a value that causes the C loop to try the callback again?
+        # at least for signals under libuv, which are delivered at very odd times.
+        # Hopefully the event still shows up when we poll the next time.
+        watcher = None
+        handle = tb.tb_frame.f_locals['handle'] if tb is not None else None
+        if handle: # handle could be NULL
+            watcher = self.from_handle(handle)
+        if watcher is not None:
+            watcher.loop.handle_error(None, t, v, tb)
+            return 1
+
+        # Raising it causes a lot of noise from CFFI
+        print("WARNING: gevent: Unhandled error with no watcher",
+              file=sys.stderr)
+        traceback.print_exception(t, v, tb)
+
+    def python_stop(self, handle):
+        if not handle: # pragma: no cover
+            print(
+                "WARNING: gevent: Unable to dereference handle; not stopping watcher. "
+                "Native resources may leak. This is most likely a bug in gevent.",
+                file=sys.stderr)
+            # The alternative is to crash with no helpful information
+            # NOTE: Raising exceptions here does nothing, they're swallowed by CFFI.
+            # Since the C level passed in a null pointer, even dereferencing the handle
+            # will just produce some exceptions.
+            return
+        watcher = self.from_handle(handle)
+        watcher.stop()
+
+    if not PYPY:
+        def python_check_callback(self, watcher_ptr): # pylint:disable=unused-argument
+            # If we have the onerror callback, this is a no-op; all the real
+            # work to rethrow the exception is done by the onerror callback
+
+            # NOTE: Unlike the rest of the functions, this is called with a pointer
+            # to the C level structure, *not* a pointer to the void* that represents a
+            # <cdata> for the Python Watcher object.
+            pass
+    else: # PyPy
+        # On PyPy, we need the function to have some sort of body, otherwise
+        # the signal exceptions don't always get caught, *especially* with
+        # libuv (however, there's no reason to expect this to only be a libuv
+        # issue; it's just that we don't depend on the periodic signal timer
+        # under libev, so the issue is much more pronounced under libuv)
+        # test_socket's test_sendall_interrupted can hang.
+        # See https://github.com/gevent/gevent/issues/1112
+
+        def python_check_callback(self, watcher_ptr): # pylint:disable=unused-argument
+            # Things we've tried that *don't* work:
+            # greenlet.getcurrent()
+            # 1 + 1
+            try:
+                raise MemoryError()
+            except MemoryError:
+                pass
+
+    def python_prepare_callback(self, watcher_ptr):
+        loop = self._find_loop_from_c_watcher(watcher_ptr)
+        if loop is None: # pragma: no cover
+            print("WARNING: gevent: running prepare callbacks from a destroyed handle: ",
+                  watcher_ptr)
+            return
+        loop._run_callbacks()
+
+    def check_callback_onerror(self, t, v, tb):
+        watcher_ptr = tb.tb_frame.f_locals['watcher_ptr'] if tb is not None else None
+        if watcher_ptr:
+            loop = self._find_loop_from_c_watcher(watcher_ptr)
+        if loop is not None:
+            # None as the context argument causes the exception to be raised
+            # in the main greenlet.
+            loop.handle_error(None, t, v, tb)
+            return None
+        raise v # Let CFFI print
+
+    def _find_loop_from_c_watcher(self, watcher_ptr):
+        raise NotImplementedError()
+
+
+
+def assign_standard_callbacks(ffi, lib, callbacks_class, extras=()): # pylint:disable=unused-argument
+    # callbacks keeps these cdata objects alive at the python level
+    callbacks = callbacks_class(ffi)
+    extras = tuple([(getattr(callbacks, name), error) for name, error in extras])
+    for (func, error_func) in ((callbacks.python_callback, None),
+                               (callbacks.python_handle_error, None),
+                               (callbacks.python_stop, None),
+                               (callbacks.python_check_callback,
+                                callbacks.check_callback_onerror),
+                               (callbacks.python_prepare_callback,
+                                callbacks.check_callback_onerror)) + extras:
+        # The name of the callback function matches the 'extern Python' declaration.
+        error_func = error_func or callbacks.unhandled_onerror
+        callback = ffi.def_extern(onerror=error_func)(func)
+        # keep alive the cdata
+        # (def_extern returns the original function, and it requests that
+        # the function be "global", so maybe it keeps a hard reference to it somewhere now
+        # unlike ffi.callback(), and we don't need to do this?)
+        callbacks.callbacks.append(callback)
+
+        # At this point, the library C variable (static function, actually)
+        # is filled in.
+
+    return callbacks
+
+
+if sys.version_info[0] >= 3:
+    basestring = (bytes, str)
+    integer_types = (int,)
+else:
+    import __builtin__ # pylint:disable=import-error
+    basestring = (__builtin__.basestring,)
+    integer_types = (int, __builtin__.long)
+
+
+
+
+_NOARGS = ()
+
+CALLBACK_CHECK_COUNT = 50
+
+class AbstractLoop(object):
+    # pylint:disable=too-many-public-methods,too-many-instance-attributes
+
+    error_handler = None
+
+    _CHECK_POINTER = None
+
+    _TIMER_POINTER = None
+    _TIMER_CALLBACK_SIG = None
+
+    _PREPARE_POINTER = None
+
+    starting_timer_may_update_loop_time = False
+
+    # Subclasses should set this in __init__ to reflect
+    # whether they were the default loop.
+    _default = None
+
+    def __init__(self, ffi, lib, watchers, flags=None, default=None):
+        self._ffi = ffi
+        self._lib = lib
+        self._ptr = None
+        self._handle_to_self = self._ffi.new_handle(self) # XXX: Reference cycle?
+        self._watchers = watchers
+        self._in_callback = False
+        self._callbacks = deque()
+        # Stores python watcher objects while they are started
+        self._keepaliveset = set()
+        self._init_loop_and_aux_watchers(flags, default)
+
+
+    def _init_loop_and_aux_watchers(self, flags=None, default=None):
+
+        self._ptr = self._init_loop(flags, default)
+
+
+        # self._check is a watcher that runs in each iteration of the
+        # mainloop, just after the blocking call. It's point is to handle
+        # signals. It doesn't run watchers or callbacks, it just exists to give
+        # CFFI a chance to raise signal exceptions so we can handle them.
+        self._check = self._ffi.new(self._CHECK_POINTER)
+        self._check.data = self._handle_to_self
+        self._init_and_start_check()
+
+        # self._prepare is a watcher that runs in each iteration of the mainloop,
+        # just before the blocking call. It's where we run deferred callbacks
+        # from self.run_callback. This cooperates with _setup_for_run_callback()
+        # to schedule self._timer0 if needed.
+        self._prepare = self._ffi.new(self._PREPARE_POINTER)
+        self._prepare.data = self._handle_to_self
+        self._init_and_start_prepare()
+
+        # A timer we start and stop on demand. If we have callbacks,
+        # too many to run in one iteration of _run_callbacks, we turn this
+        # on so as to have the next iteration of the run loop return to us
+        # as quickly as possible.
+        # TODO: There may be a more efficient way to do this using ev_timer_again;
+        # see the "ev_timer" section of the ev manpage (http://linux.die.net/man/3/ev)
+        # Alternatively, setting the ev maximum block time may also work.
+        self._timer0 = self._ffi.new(self._TIMER_POINTER)
+        self._timer0.data = self._handle_to_self
+        self._init_callback_timer()
+
+        # TODO: We may be able to do something nicer and use the existing python_callback
+        # combined with onerror and the class check/timer/prepare to simplify things
+        # and unify our handling
+
+    def _init_loop(self, flags, default):
+        """
+        Called by __init__ to create or find the loop. The return value
+        is assigned to self._ptr.
+        """
+        raise NotImplementedError()
+
+    def _init_and_start_check(self):
+        raise NotImplementedError()
+
+    def _init_and_start_prepare(self):
+        raise NotImplementedError()
+
+    def _init_callback_timer(self):
+        raise NotImplementedError()
+
+    def _stop_callback_timer(self):
+        raise NotImplementedError()
+
+    def _start_callback_timer(self):
+        raise NotImplementedError()
+
+    def _check_callback_handle_error(self, t, v, tb):
+        self.handle_error(None, t, v, tb)
+
+    def _run_callbacks(self): # pylint:disable=too-many-branches
+        # When we're running callbacks, its safe for timers to
+        # update the notion of the current time (because if we're here,
+        # we're not running in a timer callback that may let other timers
+        # run; this is mostly an issue for libuv).
+
+        # That's actually a bit of a lie: on libev, self._timer0 really is
+        # a timer, and so sometimes this is running in a timer callback, not
+        # a prepare callback. But that's OK, libev doesn't suffer from cascading
+        # timer expiration and its safe to update the loop time at any
+        # moment there.
+        self.starting_timer_may_update_loop_time = True
+        try:
+            count = CALLBACK_CHECK_COUNT
+            now = self.now()
+            expiration = now + getswitchinterval()
+            self._stop_callback_timer()
+            while self._callbacks:
+                cb = self._callbacks.popleft() # pylint:disable=assignment-from-no-return
+                count -= 1
+                self.unref() # XXX: libuv doesn't have a global ref count!
+                callback = cb.callback
+                cb.callback = None
+                args = cb.args
+                if callback is None or args is None:
+                    # it's been stopped
+                    continue
+
+                try:
+                    callback(*args)
+                except: # pylint:disable=bare-except
+                    # If we allow an exception to escape this method (while we are running the ev callback),
+                    # then CFFI will print the error and libev will continue executing.
+                    # There are two problems with this. The first is that the code after
+                    # the loop won't run. The second is that any remaining callbacks scheduled
+                    # for this loop iteration will be silently dropped; they won't run, but they'll
+                    # also not be *stopped* (which is not a huge deal unless you're looking for
+                    # consistency or checking the boolean/pending status; the loop doesn't keep
+                    # a reference to them like it does to watchers...*UNLESS* the callback itself had
+                    # a reference to a watcher; then I don't know what would happen, it depends on
+                    # the state of the watcher---a leak or crash is not totally inconceivable).
+                    # The Cython implementation in core.ppyx uses gevent_call from callbacks.c
+                    # to run the callback, which uses gevent_handle_error to handle any errors the
+                    # Python callback raises...it unconditionally simply prints any error raised
+                    # by loop.handle_error and clears it, so callback handling continues.
+                    # We take a similar approach (but are extra careful about printing)
+                    try:
+                        self.handle_error(cb, *sys.exc_info())
+                    except: # pylint:disable=bare-except
+                        try:
+                            print("Exception while handling another error", file=sys.stderr)
+                            traceback.print_exc()
+                        except: # pylint:disable=bare-except
+                            pass # Nothing we can do here
+                finally:
+                    # NOTE: this must be reset here, because cb.args is used as a flag in
+                    # the callback class so that bool(cb) of a callback that has been run
+                    # becomes False
+                    cb.args = None
+
+                # We've finished running one group of callbacks
+                # but we may have more, so before looping check our
+                # switch interval.
+                if count == 0 and self._callbacks:
+                    count = CALLBACK_CHECK_COUNT
+                    self.update_now()
+                    if self.now() >= expiration:
+                        now = 0
+                        break
+
+            # Update the time before we start going again, if we didn't
+            # just do so.
+            if now != 0:
+                self.update_now()
+
+            if self._callbacks:
+                self._start_callback_timer()
+        finally:
+            self.starting_timer_may_update_loop_time = False
+
+    def _stop_aux_watchers(self):
+        raise NotImplementedError()
+
+    def destroy(self):
+        if self._ptr:
+            try:
+                if not self._can_destroy_loop(self._ptr):
+                    return False
+                self._stop_aux_watchers()
+                self._destroy_loop(self._ptr)
+            finally:
+                # not ffi.NULL, we don't want something that can be
+                # passed to C and crash later. This will create nice friendly
+                # TypeError from CFFI.
+                self._ptr = None
+                del self._handle_to_self
+                del self._callbacks
+                del self._keepaliveset
+
+            return True
+
+    def _can_destroy_loop(self, ptr):
+        raise NotImplementedError()
+
+    def _destroy_loop(self, ptr):
+        raise NotImplementedError()
+
+    @property
+    def ptr(self):
+        return self._ptr
+
+    @property
+    def WatcherType(self):
+        return self._watchers.watcher
+
+    @property
+    def MAXPRI(self):
+        return 1
+
+    @property
+    def MINPRI(self):
+        return 1
+
+    def _handle_syserr(self, message, errno):
+        try:
+            errno = os.strerror(errno)
+        except: # pylint:disable=bare-except
+            traceback.print_exc()
+        try:
+            message = '%s: %s' % (message, errno)
+        except: # pylint:disable=bare-except
+            traceback.print_exc()
+        self.handle_error(None, SystemError, SystemError(message), None)
+
+    def handle_error(self, context, type, value, tb):
+        handle_error = None
+        error_handler = self.error_handler
+        if error_handler is not None:
+            # we do want to do getattr every time so that setting Hub.handle_error property just works
+            handle_error = getattr(error_handler, 'handle_error', error_handler)
+            handle_error(context, type, value, tb)
+        else:
+            self._default_handle_error(context, type, value, tb)
+
+    def _default_handle_error(self, context, type, value, tb): # pylint:disable=unused-argument
+        # note: Hub sets its own error handler so this is not used by gevent
+        # this is here to make core.loop usable without the rest of gevent
+        # Should cause the loop to stop running.
+        traceback.print_exception(type, value, tb)
+
+
+    def run(self, nowait=False, once=False):
+        raise NotImplementedError()
+
+    def reinit(self):
+        raise NotImplementedError()
+
+    def ref(self):
+        # XXX: libuv doesn't do it this way
+        raise NotImplementedError()
+
+    def unref(self):
+        raise NotImplementedError()
+
+    def break_(self, how=None):
+        raise NotImplementedError()
+
+    def verify(self):
+        pass
+
+    def now(self):
+        raise NotImplementedError()
+
+    def update_now(self):
+        raise NotImplementedError()
+
+    def update(self):
+        import warnings
+        warnings.warn("'update' is deprecated; use 'update_now'",
+                      DeprecationWarning,
+                      stacklevel=2)
+        self.update_now()
+
+    def __repr__(self):
+        return '<%s at 0x%x %s>' % (self.__class__.__name__, id(self), self._format())
+
+    @property
+    def default(self):
+        return self._default if self._ptr else False
+
+    @property
+    def iteration(self):
+        return -1
+
+    @property
+    def depth(self):
+        return -1
+
+    @property
+    def backend_int(self):
+        return 0
+
+    @property
+    def backend(self):
+        return "default"
+
+    @property
+    def pendingcnt(self):
+        return 0
+
+    def io(self, fd, events, ref=True, priority=None):
+        return self._watchers.io(self, fd, events, ref, priority)
+
+    def timer(self, after, repeat=0.0, ref=True, priority=None):
+        return self._watchers.timer(self, after, repeat, ref, priority)
+
+    def signal(self, signum, ref=True, priority=None):
+        return self._watchers.signal(self, signum, ref, priority)
+
+    def idle(self, ref=True, priority=None):
+        return self._watchers.idle(self, ref, priority)
+
+    def prepare(self, ref=True, priority=None):
+        return self._watchers.prepare(self, ref, priority)
+
+    def check(self, ref=True, priority=None):
+        return self._watchers.check(self, ref, priority)
+
+    def fork(self, ref=True, priority=None):
+        return self._watchers.fork(self, ref, priority)
+
+    def async_(self, ref=True, priority=None):
+        return self._watchers.async_(self, ref, priority)
+
+    # Provide BWC for those that can use 'async' as is
+    locals()['async'] = async_
+
+    if sys.platform != "win32":
+
+        def child(self, pid, trace=0, ref=True):
+            return self._watchers.child(self, pid, trace, ref)
+
+        def install_sigchld(self):
+            pass
+
+    def stat(self, path, interval=0.0, ref=True, priority=None):
+        return self._watchers.stat(self, path, interval, ref, priority)
+
+    def callback(self, priority=None):
+        return callback(self, priority)
+
+    def _setup_for_run_callback(self):
+        raise NotImplementedError()
+
+    def run_callback(self, func, *args):
+        # If we happen to already be running callbacks (inside
+        # _run_callbacks), this could happen almost immediately,
+        # without the loop cycling.
+        cb = callback(func, args)
+        self._callbacks.append(cb)
+        self._setup_for_run_callback()
+
+        return cb
+
+    def _format(self):
+        if not self._ptr:
+            return 'destroyed'
+        msg = self.backend
+        if self.default:
+            msg += ' default'
+        msg += ' pending=%s' % self.pendingcnt
+        msg += self._format_details()
+        return msg
+
+    def _format_details(self):
+        msg = ''
+        fileno = self.fileno() # pylint:disable=assignment-from-none
+        try:
+            activecnt = self.activecnt
+        except AttributeError:
+            activecnt = None
+        if activecnt is not None:
+            msg += ' ref=' + repr(activecnt)
+        if fileno is not None:
+            msg += ' fileno=' + repr(fileno)
+        #if sigfd is not None and sigfd != -1:
+        #    msg += ' sigfd=' + repr(sigfd)
+        return msg
+
+    def fileno(self):
+        return None
+
+    @property
+    def activecnt(self):
+        if not self._ptr:
+            raise ValueError('operation on destroyed loop')
+        return 0