Code import

venv/lib/python2.7/site-packages/eventlet/hubs/hub.py

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+import errno
+import heapq
+import math
+import signal
+import sys
+import traceback
+
+arm_alarm = None
+if hasattr(signal, 'setitimer'):
+    def alarm_itimer(seconds):
+        signal.setitimer(signal.ITIMER_REAL, seconds)
+    arm_alarm = alarm_itimer
+else:
+    try:
+        import itimer
+        arm_alarm = itimer.alarm
+    except ImportError:
+        def alarm_signal(seconds):
+            signal.alarm(math.ceil(seconds))
+        arm_alarm = alarm_signal
+
+from eventlet.hubs import timer, IOClosed
+from eventlet.support import greenlets as greenlet, clear_sys_exc_info, monotonic, six
+
+g_prevent_multiple_readers = True
+
+READ = "read"
+WRITE = "write"
+
+
+def closed_callback(fileno):
+    """ Used to de-fang a callback that may be triggered by a loop in BaseHub.wait
+    """
+    # No-op.
+    pass
+
+
+class FdListener(object):
+
+    def __init__(self, evtype, fileno, cb, tb, mark_as_closed):
+        """ The following are required:
+        cb - the standard callback, which will switch into the
+            listening greenlet to indicate that the event waited upon
+            is ready
+        tb - a 'throwback'. This is typically greenlet.throw, used
+            to raise a signal into the target greenlet indicating that
+            an event was obsoleted by its underlying filehandle being
+            repurposed.
+        mark_as_closed - if any listener is obsoleted, this is called
+            (in the context of some other client greenlet) to alert
+            underlying filehandle-wrapping objects that they've been
+            closed.
+        """
+        assert (evtype is READ or evtype is WRITE)
+        self.evtype = evtype
+        self.fileno = fileno
+        self.cb = cb
+        self.tb = tb
+        self.mark_as_closed = mark_as_closed
+        self.spent = False
+        self.greenlet = greenlet.getcurrent()
+
+    def __repr__(self):
+        return "%s(%r, %r, %r, %r)" % (type(self).__name__, self.evtype, self.fileno,
+                                       self.cb, self.tb)
+    __str__ = __repr__
+
+    def defang(self):
+        self.cb = closed_callback
+        if self.mark_as_closed is not None:
+            self.mark_as_closed()
+        self.spent = True
+
+
+noop = FdListener(READ, 0, lambda x: None, lambda x: None, None)
+
+
+# in debug mode, track the call site that created the listener
+
+
+class DebugListener(FdListener):
+
+    def __init__(self, evtype, fileno, cb, tb, mark_as_closed):
+        self.where_called = traceback.format_stack()
+        self.greenlet = greenlet.getcurrent()
+        super(DebugListener, self).__init__(evtype, fileno, cb, tb, mark_as_closed)
+
+    def __repr__(self):
+        return "DebugListener(%r, %r, %r, %r, %r, %r)\n%sEndDebugFdListener" % (
+            self.evtype,
+            self.fileno,
+            self.cb,
+            self.tb,
+            self.mark_as_closed,
+            self.greenlet,
+            ''.join(self.where_called))
+    __str__ = __repr__
+
+
+def alarm_handler(signum, frame):
+    import inspect
+    raise RuntimeError("Blocking detector ALARMED at" + str(inspect.getframeinfo(frame)))
+
+
+class BaseHub(object):
+    """ Base hub class for easing the implementation of subclasses that are
+    specific to a particular underlying event architecture. """
+
+    SYSTEM_EXCEPTIONS = (KeyboardInterrupt, SystemExit)
+
+    READ = READ
+    WRITE = WRITE
+
+    def __init__(self, clock=None):
+        self.listeners = {READ: {}, WRITE: {}}
+        self.secondaries = {READ: {}, WRITE: {}}
+        self.closed = []
+
+        if clock is None:
+            clock = monotonic.monotonic
+        self.clock = clock
+
+        self.greenlet = greenlet.greenlet(self.run)
+        self.stopping = False
+        self.running = False
+        self.timers = []
+        self.next_timers = []
+        self.lclass = FdListener
+        self.timers_canceled = 0
+        self.debug_exceptions = True
+        self.debug_blocking = False
+        self.debug_blocking_resolution = 1
+
+    def block_detect_pre(self):
+        # shortest alarm we can possibly raise is one second
+        tmp = signal.signal(signal.SIGALRM, alarm_handler)
+        if tmp != alarm_handler:
+            self._old_signal_handler = tmp
+
+        arm_alarm(self.debug_blocking_resolution)
+
+    def block_detect_post(self):
+        if (hasattr(self, "_old_signal_handler") and
+                self._old_signal_handler):
+            signal.signal(signal.SIGALRM, self._old_signal_handler)
+        signal.alarm(0)
+
+    def add(self, evtype, fileno, cb, tb, mark_as_closed):
+        """ Signals an intent to or write a particular file descriptor.
+
+        The *evtype* argument is either the constant READ or WRITE.
+
+        The *fileno* argument is the file number of the file of interest.
+
+        The *cb* argument is the callback which will be called when the file
+        is ready for reading/writing.
+
+        The *tb* argument is the throwback used to signal (into the greenlet)
+        that the file was closed.
+
+        The *mark_as_closed* is used in the context of the event hub to
+        prepare a Python object as being closed, pre-empting further
+        close operations from accidentally shutting down the wrong OS thread.
+        """
+        listener = self.lclass(evtype, fileno, cb, tb, mark_as_closed)
+        bucket = self.listeners[evtype]
+        if fileno in bucket:
+            if g_prevent_multiple_readers:
+                raise RuntimeError(
+                    "Second simultaneous %s on fileno %s "
+                    "detected.  Unless you really know what you're doing, "
+                    "make sure that only one greenthread can %s any "
+                    "particular socket.  Consider using a pools.Pool. "
+                    "If you do know what you're doing and want to disable "
+                    "this error, call "
+                    "eventlet.debug.hub_prevent_multiple_readers(False) - MY THREAD=%s; "
+                    "THAT THREAD=%s" % (
+                        evtype, fileno, evtype, cb, bucket[fileno]))
+            # store off the second listener in another structure
+            self.secondaries[evtype].setdefault(fileno, []).append(listener)
+        else:
+            bucket[fileno] = listener
+        return listener
+
+    def _obsolete(self, fileno):
+        """ We've received an indication that 'fileno' has been obsoleted.
+            Any current listeners must be defanged, and notifications to
+            their greenlets queued up to send.
+        """
+        found = False
+        for evtype, bucket in six.iteritems(self.secondaries):
+            if fileno in bucket:
+                for listener in bucket[fileno]:
+                    found = True
+                    self.closed.append(listener)
+                    listener.defang()
+                del bucket[fileno]
+
+        # For the primary listeners, we actually need to call remove,
+        # which may modify the underlying OS polling objects.
+        for evtype, bucket in six.iteritems(self.listeners):
+            if fileno in bucket:
+                listener = bucket[fileno]
+                found = True
+                self.closed.append(listener)
+                self.remove(listener)
+                listener.defang()
+
+        return found
+
+    def notify_close(self, fileno):
+        """ We might want to do something when a fileno is closed.
+            However, currently it suffices to obsolete listeners only
+            when we detect an old fileno being recycled, on open.
+        """
+        pass
+
+    def remove(self, listener):
+        if listener.spent:
+            # trampoline may trigger this in its finally section.
+            return
+
+        fileno = listener.fileno
+        evtype = listener.evtype
+        self.listeners[evtype].pop(fileno, None)
+        # migrate a secondary listener to be the primary listener
+        if fileno in self.secondaries[evtype]:
+            sec = self.secondaries[evtype].get(fileno, None)
+            if not sec:
+                return
+            self.listeners[evtype][fileno] = sec.pop(0)
+            if not sec:
+                del self.secondaries[evtype][fileno]
+
+    def mark_as_reopened(self, fileno):
+        """ If a file descriptor is returned by the OS as the result of some
+            open call (or equivalent), that signals that it might be being
+            recycled.
+
+            Catch the case where the fd was previously in use.
+        """
+        self._obsolete(fileno)
+
+    def remove_descriptor(self, fileno):
+        """ Completely remove all listeners for this fileno.  For internal use
+        only."""
+        listeners = []
+        listeners.append(self.listeners[READ].pop(fileno, noop))
+        listeners.append(self.listeners[WRITE].pop(fileno, noop))
+        listeners.extend(self.secondaries[READ].pop(fileno, ()))
+        listeners.extend(self.secondaries[WRITE].pop(fileno, ()))
+        for listener in listeners:
+            try:
+                listener.cb(fileno)
+            except Exception:
+                self.squelch_generic_exception(sys.exc_info())
+
+    def close_one(self):
+        """ Triggered from the main run loop. If a listener's underlying FD was
+            closed somehow, throw an exception back to the trampoline, which should
+            be able to manage it appropriately.
+        """
+        listener = self.closed.pop()
+        if not listener.greenlet.dead:
+            # There's no point signalling a greenlet that's already dead.
+            listener.tb(IOClosed(errno.ENOTCONN, "Operation on closed file"))
+
+    def ensure_greenlet(self):
+        if self.greenlet.dead:
+            # create new greenlet sharing same parent as original
+            new = greenlet.greenlet(self.run, self.greenlet.parent)
+            # need to assign as parent of old greenlet
+            # for those greenlets that are currently
+            # children of the dead hub and may subsequently
+            # exit without further switching to hub.
+            self.greenlet.parent = new
+            self.greenlet = new
+
+    def switch(self):
+        cur = greenlet.getcurrent()
+        assert cur is not self.greenlet, 'Cannot switch to MAINLOOP from MAINLOOP'
+        switch_out = getattr(cur, 'switch_out', None)
+        if switch_out is not None:
+            try:
+                switch_out()
+            except:
+                self.squelch_generic_exception(sys.exc_info())
+        self.ensure_greenlet()
+        try:
+            if self.greenlet.parent is not cur:
+                cur.parent = self.greenlet
+        except ValueError:
+            pass  # gets raised if there is a greenlet parent cycle
+        clear_sys_exc_info()
+        return self.greenlet.switch()
+
+    def squelch_exception(self, fileno, exc_info):
+        traceback.print_exception(*exc_info)
+        sys.stderr.write("Removing descriptor: %r\n" % (fileno,))
+        sys.stderr.flush()
+        try:
+            self.remove_descriptor(fileno)
+        except Exception as e:
+            sys.stderr.write("Exception while removing descriptor! %r\n" % (e,))
+            sys.stderr.flush()
+
+    def wait(self, seconds=None):
+        raise NotImplementedError("Implement this in a subclass")
+
+    def default_sleep(self):
+        return 60.0
+
+    def sleep_until(self):
+        t = self.timers
+        if not t:
+            return None
+        return t[0][0]
+
+    def run(self, *a, **kw):
+        """Run the runloop until abort is called.
+        """
+        # accept and discard variable arguments because they will be
+        # supplied if other greenlets have run and exited before the
+        # hub's greenlet gets a chance to run
+        if self.running:
+            raise RuntimeError("Already running!")
+        try:
+            self.running = True
+            self.stopping = False
+            while not self.stopping:
+                while self.closed:
+                    # We ditch all of these first.
+                    self.close_one()
+                self.prepare_timers()
+                if self.debug_blocking:
+                    self.block_detect_pre()
+                self.fire_timers(self.clock())
+                if self.debug_blocking:
+                    self.block_detect_post()
+                self.prepare_timers()
+                wakeup_when = self.sleep_until()
+                if wakeup_when is None:
+                    sleep_time = self.default_sleep()
+                else:
+                    sleep_time = wakeup_when - self.clock()
+                if sleep_time > 0:
+                    self.wait(sleep_time)
+                else:
+                    self.wait(0)
+            else:
+                self.timers_canceled = 0
+                del self.timers[:]
+                del self.next_timers[:]
+        finally:
+            self.running = False
+            self.stopping = False
+
+    def abort(self, wait=False):
+        """Stop the runloop. If run is executing, it will exit after
+        completing the next runloop iteration.
+
+        Set *wait* to True to cause abort to switch to the hub immediately and
+        wait until it's finished processing.  Waiting for the hub will only
+        work from the main greenthread; all other greenthreads will become
+        unreachable.
+        """
+        if self.running:
+            self.stopping = True
+        if wait:
+            assert self.greenlet is not greenlet.getcurrent(
+            ), "Can't abort with wait from inside the hub's greenlet."
+            # schedule an immediate timer just so the hub doesn't sleep
+            self.schedule_call_global(0, lambda: None)
+            # switch to it; when done the hub will switch back to its parent,
+            # the main greenlet
+            self.switch()
+
+    def squelch_generic_exception(self, exc_info):
+        if self.debug_exceptions:
+            traceback.print_exception(*exc_info)
+            sys.stderr.flush()
+            clear_sys_exc_info()
+
+    def squelch_timer_exception(self, timer, exc_info):
+        if self.debug_exceptions:
+            traceback.print_exception(*exc_info)
+            sys.stderr.flush()
+            clear_sys_exc_info()
+
+    def add_timer(self, timer):
+        scheduled_time = self.clock() + timer.seconds
+        self.next_timers.append((scheduled_time, timer))
+        return scheduled_time
+
+    def timer_canceled(self, timer):
+        self.timers_canceled += 1
+        len_timers = len(self.timers) + len(self.next_timers)
+        if len_timers > 1000 and len_timers / 2 <= self.timers_canceled:
+            self.timers_canceled = 0
+            self.timers = [t for t in self.timers if not t[1].called]
+            self.next_timers = [t for t in self.next_timers if not t[1].called]
+            heapq.heapify(self.timers)
+
+    def prepare_timers(self):
+        heappush = heapq.heappush
+        t = self.timers
+        for item in self.next_timers:
+            if item[1].called:
+                self.timers_canceled -= 1
+            else:
+                heappush(t, item)
+        del self.next_timers[:]
+
+    def schedule_call_local(self, seconds, cb, *args, **kw):
+        """Schedule a callable to be called after 'seconds' seconds have
+        elapsed. Cancel the timer if greenlet has exited.
+            seconds: The number of seconds to wait.
+            cb: The callable to call after the given time.
+            *args: Arguments to pass to the callable when called.
+            **kw: Keyword arguments to pass to the callable when called.
+        """
+        t = timer.LocalTimer(seconds, cb, *args, **kw)
+        self.add_timer(t)
+        return t
+
+    def schedule_call_global(self, seconds, cb, *args, **kw):
+        """Schedule a callable to be called after 'seconds' seconds have
+        elapsed. The timer will NOT be canceled if the current greenlet has
+        exited before the timer fires.
+            seconds: The number of seconds to wait.
+            cb: The callable to call after the given time.
+            *args: Arguments to pass to the callable when called.
+            **kw: Keyword arguments to pass to the callable when called.
+        """
+        t = timer.Timer(seconds, cb, *args, **kw)
+        self.add_timer(t)
+        return t
+
+    def fire_timers(self, when):
+        t = self.timers
+        heappop = heapq.heappop
+
+        while t:
+            next = t[0]
+
+            exp = next[0]
+            timer = next[1]
+
+            if when < exp:
+                break
+
+            heappop(t)
+
+            try:
+                if timer.called:
+                    self.timers_canceled -= 1
+                else:
+                    timer()
+            except self.SYSTEM_EXCEPTIONS:
+                raise
+            except:
+                self.squelch_timer_exception(timer, sys.exc_info())
+                clear_sys_exc_info()
+
+    # for debugging:
+
+    def get_readers(self):
+        return self.listeners[READ].values()
+
+    def get_writers(self):
+        return self.listeners[WRITE].values()
+
+    def get_timers_count(hub):
+        return len(hub.timers) + len(hub.next_timers)
+
+    def set_debug_listeners(self, value):
+        if value:
+            self.lclass = DebugListener
+        else:
+            self.lclass = FdListener
+
+    def set_timer_exceptions(self, value):
+        self.debug_exceptions = value