Source code for pychron.hardware.core.communicators.scheduler
# ===============================================================================
# Copyright 2011 Jake Ross
#
# 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.
# ===============================================================================
# ============= enthought library imports =======================
from __future__ import absolute_import
from traits.api import Float, HasTraits
# ============= standard library imports ========================
from threading import Lock
# ============= local library imports ==========================
# SINGLE_ITEM_BUF = True
# SINGLE_ITEM_BUF=False
[docs]class CommunicationScheduler(HasTraits):
"""
this class should be used when working with multiple rs485 devices on the same port.
it uses a simple lock and sleep cycle to avoid collision on the data lines
when setting up the devices use device.set_scheduler to set the shared scheduler
"""
# collision_delay = Float(125)
collision_delay = Float(50)
def __init__(self, *args, **kw):
super(CommunicationScheduler, self).__init__(*args, **kw)
self._lock = Lock()
# self._condition = Condition()
# self._command_queue = Queue()
# self._buffer = Queue()
#
# consumer = Consumer(self._command_queue,
# self._buffer,
# # self._condition,
# self.collision_delay)
# consumer.start()
def schedule(self, func, args=None, kwargs=None):
if args is None:
args = tuple()
if kwargs is None:
kwargs = dict()
# while SINGLE_ITEM_BUF and not self._buffer.empty():
# time.sleep(0.0001)
#
# self._command_queue.put((func, args, kwargs))
#
# try:
# r = self._buffer.get(timeout=0.5)
# except Empty:
# r = None
with self._lock:
r = func(*args, **kwargs)
return r
# class Consumer(Thread):
#
# def __init__(self, q, b, cd):
# Thread.__init__(self)
# self._q = q
# self._buf = b
# # self.logger = add_console(name='consumer')
# # self.cond = cond
# self.cd = cd
#
# def run(self):
# while 1:
# # self.cond.acquire()
# while self._q.empty():
# time.sleep(0.0001)
# # self.cond.wait(timeout=0.05)
# # st = time.time()
# func, args, kwargs = self._q.get()
#
# while SINGLE_ITEM_BUF and not self._buf.empty():
# time.sleep(0.0001)
#
# r = func(*args, **kwargs)
# # self.logger.info(r)
# self._buf.put(r)
# # self.cond.release()
#
# # time.sleep(self.cd/1000.)
# # time.sleep(max(0.0001, self.cd / 1000. - (time.time() - st) - 0.001))
# ============= EOF ====================================