/usr/lib/python3/dist-packages/async/util.py is in python3-async 0.6.2-2.
This file is owned by root:root, with mode 0o644.
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#
# This module is part of async and is released under
# the New BSD License: http://www.opensource.org/licenses/bsd-license.php
"""Module with utilities related to async operations"""
from threading import (
Lock,
_allocate_lock,
_time,
)
try:
from queue import Empty
except ImportError:
from Queue import Empty
from collections import deque
import sys
import os
import time
#{ Routines
def cpu_count():
""":return:number of CPUs in the system
:note: inspired by multiprocessing"""
num = 0
try:
if sys.platform == 'win32':
num = int(os.environ['NUMBER_OF_PROCESSORS'])
elif 'bsd' in sys.platform or sys.platform == 'darwin':
num = int(os.popen('sysctl -n hw.ncpu').read())
else:
num = os.sysconf('SC_NPROCESSORS_ONLN')
except (ValueError, KeyError, OSError, AttributeError):
pass
# END exception handling
if num == 0:
raise NotImplementedError('cannot determine number of cpus')
return num
#} END routines
class DummyLock(object):
"""An object providing a do-nothing lock interface for use in sync mode"""
__slots__ = tuple()
def acquire(self):
pass
def release(self):
pass
class SyncQueue(deque):
"""Adapter to allow using a deque like a queue, without locking"""
def get(self, block=True, timeout=None):
try:
return self.popleft()
except IndexError:
raise Empty
# END raise empty
def empty(self):
return len(self) == 0
def set_writable(self, state):
pass
def writable(self):
return True
def put(self, item, block=True, timeout=None):
self.append(item)
class HSCondition(deque):
"""Cleaned up code of the original condition object in order
to make it run and respond faster."""
__slots__ = ("_lock")
delay = 0.0002 # reduces wait times, but increases overhead
def __init__(self, lock=None):
if lock is None:
lock = Lock()
self._lock = lock
def release(self):
self._lock.release()
def acquire(self, block=None):
if block is None:
self._lock.acquire()
else:
self._lock.acquire(block)
def wait(self, timeout=None):
waiter = _allocate_lock()
waiter.acquire() # get it the first time, no blocking
self.append(waiter)
try:
# restore state no matter what (e.g., KeyboardInterrupt)
# now we block, as we hold the lock already
# in the momemnt we release our lock, someone else might actually resume
self._lock.release()
if timeout is None:
waiter.acquire()
else:
# Balancing act: We can't afford a pure busy loop, because of the
# GIL, so we have to sleep
# We try to sleep only tiny amounts of time though to be very responsive
# NOTE: this branch is not used by the async system anyway, but
# will be hit when the user reads with timeout
endtime = _time() + timeout
delay = self.delay
acquire = waiter.acquire
while True:
gotit = acquire(0)
if gotit:
break
remaining = endtime - _time()
if remaining <= 0:
break
# this makes 4 threads working as good as two, but of course
# it causes more frequent micro-sleeping
#delay = min(delay * 2, remaining, .05)
time.sleep(delay)
# END endless loop
if not gotit:
try:
self.remove(waiter)
except AttributeError:
# handle python 2.4 - actually this should be made thread-safe
# but lets see ...
try:
# lets hope we pop the right one - we don't loop over it
# yet-we just keep minimal compatability with py 2.4
item = self.pop()
if item != waiter:
self.append(item)
except IndexError:
pass
except ValueError:
pass
# END didn't ever get it
finally:
# reacquire the lock
self._lock.acquire()
# END assure release lock
def notify(self, n=1):
"""Its vital that this method is threadsafe - we absolutely have to
get a lock at the beginning of this method to be sure we get the
correct amount of waiters back. If we bail out, although a waiter
is about to be added, it will miss its wakeup notification, and block
forever (possibly)"""
self._lock.acquire()
try:
if not self: # len(self) == 0, but this should be faster
return
if n == 1:
try:
self.popleft().release()
except IndexError:
pass
else:
for i in range(min(n, len(self))):
self.popleft().release()
# END for each waiter to resume
# END handle n = 1 case faster
finally:
self._lock.release()
# END assure lock is released
def notify_all(self):
self.notify(len(self))
class ReadOnly(Exception):
"""Thrown when trying to write to a read-only queue"""
class AsyncQueue(deque):
"""A queue using different condition objects to gain multithreading performance.
Additionally it has a threadsafe writable flag, which will alert all readers
that there is nothing more to get here.
All default-queue code was cleaned up for performance."""
__slots__ = ('mutex', 'not_empty', '_writable')
def __init__(self, maxsize=0):
self.mutex = Lock()
self.not_empty = HSCondition(self.mutex)
self._writable = True
def qsize(self):
self.mutex.acquire()
try:
return len(self)
finally:
self.mutex.release()
def writable(self):
self.mutex.acquire()
try:
return self._writable
finally:
self.mutex.release()
def set_writable(self, state):
"""Set the writable flag of this queue to True or False
:return: The previous state"""
self.mutex.acquire()
try:
old = self._writable
self._writable = state
return old
finally:
self.mutex.release()
# if we won't receive anymore items, inform the getters
if not state:
self.not_empty.notify_all()
# END tell everyone
# END handle locking
def empty(self):
self.mutex.acquire()
try:
return not len(self)
finally:
self.mutex.release()
def put(self, item, block=True, timeout=None):
self.mutex.acquire()
# NOTE: we explicitly do NOT check for our writable state
# Its just used as a notification signal, and we need to be able
# to continue writing to prevent threads ( easily ) from failing
# to write their computed results, which we want in fact
# NO: we want them to fail and stop processing, as the one who caused
# the channel to close had a reason and wants the threads to
# stop on the task as soon as possible
if not self._writable:
self.mutex.release()
raise ReadOnly
# END handle read-only
self.append(item)
self.mutex.release()
self.not_empty.notify()
def get(self, block=True, timeout=None):
self.mutex.acquire()
try:
if block:
if timeout is None:
while not len(self) and self._writable:
self.not_empty.wait()
else:
endtime = _time() + timeout
while not len(self) and self._writable:
remaining = endtime - _time()
if remaining <= 0.0:
raise Empty
self.not_empty.wait(remaining)
# END handle timeout mode
# END handle block
# can throw if we woke up because we are not writable anymore
try:
return self.popleft()
except IndexError:
raise Empty
# END handle unblocking reason
finally:
self.mutex.release()
# END assure lock is released
#} END utilities
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