/usr/lib/python2.7/dist-packages/eventlet/hubs/hub.py is in python-eventlet 0.13.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import math
import traceback
import signal
import sys
import warnings
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.support import greenlets as greenlet, clear_sys_exc_info
from eventlet.hubs import timer
from eventlet import patcher
time = patcher.original('time')
g_prevent_multiple_readers = True
READ="read"
WRITE="write"
class FdListener(object):
def __init__(self, evtype, fileno, cb):
assert (evtype is READ or evtype is WRITE)
self.evtype = evtype
self.fileno = fileno
self.cb = cb
def __repr__(self):
return "%s(%r, %r, %r)" % (type(self).__name__, self.evtype, self.fileno, self.cb)
__str__ = __repr__
noop = FdListener(READ, 0, lambda x: None)
# in debug mode, track the call site that created the listener
class DebugListener(FdListener):
def __init__(self, evtype, fileno, cb):
self.where_called = traceback.format_stack()
self.greenlet = greenlet.getcurrent()
super(DebugListener, self).__init__(evtype, fileno, cb)
def __repr__(self):
return "DebugListener(%r, %r, %r, %r)\n%sEndDebugFdListener" % (
self.evtype,
self.fileno,
self.cb,
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=time.time):
self.listeners = {READ:{}, WRITE:{}}
self.secondaries = {READ:{}, WRITE:{}}
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):
""" 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.
"""
listener = self.lclass(evtype, fileno, cb)
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)" % (
evtype, fileno, evtype))
# store off the second listener in another structure
self.secondaries[evtype].setdefault(fileno, []).append(listener)
else:
bucket[fileno] = listener
return listener
def remove(self, listener):
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 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, e:
self.squelch_generic_exception(sys.exc_info())
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, 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:
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
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