/usr/lib/python3/dist-packages/ginga/util/heaptimer.py is in python3-ginga 2.6.1-2.
This file is owned by root:root, with mode 0o644.
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#
# Copyright (c) 2014 by Christian E. Hopps.
# All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
import heapq
import logging
import random
import time
import threading
import functools
__author__ = 'Christian Hopps'
__version__ = '1.0'
__docformat__ = "restructuredtext en"
_logger = logging.getLogger(__name__)
@functools.total_ordering
class Timer (object):
def __init__ (self, heap, jitter, action, *args, **kwargs):
self.jitter = jitter
self.action = action
self.args = args
self.kwargs = kwargs
self.expire = None
self.timer_heap = heap
self.logger = heap.logger
def run(self):
try:
self.action(*self.args, **self.kwargs)
except Exception as ex:
self.logger.error("Ignoring uncaught exception within timer action: %s", str(ex))
def __hash__(self):
return id(self)
def __lt__(self, other):
if other is None:
return -1
return self.expire < other.expire
def __eq__(self, other):
return id(self) == id(other)
def is_scheduled(self):
with self.timer_heap:
return self.expire is not None
def start(self, time_sec):
self.stop()
self.start_time = time.time()
if self.jitter:
self.expire = self.start_time + time_sec * (
1 - random.random() * self.jitter)
else:
self.expire = self.start_time + time_sec
self.timer_heap.add(self)
def cond_start(self, time_sec):
with self.timer_heap:
if not self.is_scheduled():
self.start(time_sec)
def elapsed_time(self):
"""Return the elapsed time since the timer was started."""
return time.time() - self.start_time
def remaining_time(self):
"""Return the remaining time to the timer expiration.
If the timer has already expired then None is returned.
"""
if self.expire is None:
return 0.0
return self.expire - time.time()
def stop(self):
had_run = self.timer_heap.remove(self)
self.expire = None
return had_run
class TimerHeap(object):
def __init__(self, desc='A Timer Heap', logger=None):
self.desc = desc
if logger is None:
# use module logger if user doesn't supply one
logger = _logger
self.logger = logger
self.timers = {}
self.heap = []
self.lock = threading.RLock()
self.rtimer = None
self.expiring = False
self.expire_gen = 0
def __enter__(self):
"""Use with statement to hold lock"""
return self.lock.acquire()
def __exit__(self, exc_type, exc_val, exc_tb):
"""Use with statement to hold lock"""
return self.lock.release()
def timer(self, jitter, action, *args, **kwargs):
"""Convenience method to create a Timer from the heap"""
return Timer(self, jitter, action, *args, **kwargs)
def add(self, timer):
"""Add a timer to the heap"""
with self.lock:
if self.heap:
top = self.heap[0]
else:
top = None
assert timer not in self.timers
self.timers[timer] = timer
heapq.heappush(self.heap, timer)
# Check to see if we need to reschedule our main timer.
# Only do this if we aren't expiring in the other thread.
if self.heap[0] != top and not self.expiring:
if self.rtimer is not None:
self.rtimer.cancel()
# self.rtimer.join()
self.rtimer = None
# If we are expiring timers right now then that will reschedule
# as appropriate otherwise let's start a timer if we don't have
# one
if self.rtimer is None and not self.expiring:
top = self.heap[0]
ival = top.expire - time.time()
if ival < 0:
ival = 0
self.rtimer = threading.Timer(ival, self.expire)
self.rtimer.start()
def expire(self):
try:
# Set expiring variable and forget old timer.
with self.lock:
self.expire_gen += 1
self.expiring = True
self.rtimer = None
while True:
with self.lock:
if not self.heap:
return
top = self.heap[0]
ctime = time.time()
if top.expire > ctime:
return
# remove the timer
expired = heapq.heappop(self.heap)
del self.timers[expired]
# Ok to run with lock as we use RLock
# Much safer for things like caches
expired.expire = None
expired.run()
except Exception as ex:
self.logger.error("Unexpected Exception: %s" % str(ex))
finally:
# This is never set while expiring is True
assert self.rtimer is None
with self.lock:
# Now grab the next timer and set our real-time timer and unset expiring
if self.heap:
top = self.heap[0]
ival = top.expire - time.time()
if ival < 0:
ival = 0
self.rtimer = threading.Timer(ival, self.expire)
self.rtimer.start()
self.expiring = False
def _remove(self, timer):
"""Remove timer from heap lock and presence are assumed"""
assert timer.timer_heap == self
del self.timers[timer]
assert timer in self.heap
self.heap.remove(timer)
heapq.heapify(self.heap)
def remove(self, timer):
"""Remove a timer from the heap, return True if already run"""
with self.lock:
# This is somewhat expensive as we have to heapify.
if timer in self.timers:
self._remove(timer)
return False
else:
return True
def remove_all_timers(self):
"""Remove all waiting timers and terminate any blocking threads."""
with self.lock:
if self.rtimer is not None:
self.rtimer.cancel()
self.timers = {}
self.heap = []
self.rtimer = None
self.expiring = False
def quit(self):
"""Execute this method before your program exit to make sure it
doesn't block on waiting for a timer thread to terminate."""
self.remove_all_timers()
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