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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
import eventlet.hubs
from eventlet.hubs import timer
from eventlet.support import greenlets as greenlet
try:
from monotonic import monotonic
except ImportError:
from time import monotonic
import 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
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
if listener is self.listeners[evtype][fileno]:
del self.listeners[evtype][fileno]
# migrate a secondary listener to be the primary listener
if fileno in self.secondaries[evtype]:
sec = self.secondaries[evtype][fileno]
if sec:
self.listeners[evtype][fileno] = sec.pop(0)
if not sec:
del self.secondaries[evtype][fileno]
else:
self.secondaries[evtype][fileno].remove(listener)
if not self.secondaries[evtype][fileno]:
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."""
# gather any listeners we have
listeners = []
listeners.append(self.listeners[READ].get(fileno, noop))
listeners.append(self.listeners[WRITE].get(fileno, noop))
listeners.extend(self.secondaries[READ].get(fileno, ()))
listeners.extend(self.secondaries[WRITE].get(fileno, ()))
for listener in listeners:
try:
# listener.cb may want to remove(listener)
listener.cb(fileno)
except Exception:
self.squelch_generic_exception(sys.exc_info())
# NOW this fileno is now dead to all
self.listeners[READ].pop(fileno, None)
self.listeners[WRITE].pop(fileno, None)
self.secondaries[READ].pop(fileno, None)
self.secondaries[WRITE].pop(fileno, None)
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(eventlet.hubs.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
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()
def squelch_timer_exception(self, timer, exc_info):
if self.debug_exceptions:
traceback.print_exception(*exc_info)
sys.stderr.flush()
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())
# 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