frappy/secop/lib/multievent.py
Markus Zolliker 4f7083bc98 ReadHandler and WriteHandler decorators
modules with a couple of parameters with similar read_* or
write_* methods may handle them by generic methods wrapped
with decorators ReadHandler / WriteHandler

The trinamic driver is included in this change for demonstrating
how it works.

In a further step, the special handling for the iohandler stuff can
be moved away from secop.server and secop.params, using this feature.

+ fix problem on startup of trinamic driver (needs MultiEvent.queue)
+ some other small fixes
+ apply recommended functools.wraps for wrapping

Change-Id: Ibfeff9209f53c47194628463466cee28366e17ac
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/27460
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>
2022-01-27 17:04:45 +01:00

142 lines
4.5 KiB
Python

# -*- coding: utf-8 -*-
# *****************************************************************************
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
# Module authors:
# Markus Zolliker <markus.zolliker@psi.ch>
#
# *****************************************************************************
import threading
import time
ETERNITY = 1e99
class _SingleEvent:
"""Single Event
remark: :meth:`wait` is not implemented on purpose
"""
def __init__(self, multievent, timeout, name=None):
self.multievent = multievent
self.multievent.clear_(self)
self.name = name
if timeout is None:
self.deadline = ETERNITY
else:
self.deadline = time.monotonic() + timeout
def clear(self):
self.multievent.clear_(self)
def set(self):
self.multievent.set_(self)
def is_set(self):
return self in self.multievent.events
class MultiEvent(threading.Event):
"""Class implementing multi event objects."""
def __init__(self, default_timeout=None):
self.events = set()
self._lock = threading.Lock()
self.default_timeout = default_timeout or None # treat 0 as None
self.name = None # default event name
self._actions = [] # actions to be executed on trigger
super().__init__()
def new(self, timeout=None, name=None):
"""create a single event like object"""
return _SingleEvent(self, timeout or self.default_timeout,
name or self.name or '<unnamed>')
def set(self):
raise ValueError('a multievent must not be set directly')
def clear(self):
raise ValueError('a multievent must not be cleared directly')
def is_set(self):
return not self.events
def set_(self, event):
"""internal: remove event from the event list"""
with self._lock:
self.events.discard(event)
if self.events:
return
try:
for action in self._actions:
action()
except Exception:
pass # we silently ignore errors here
self._actions = []
super().set()
def clear_(self, event):
"""internal: add event to the event list"""
with self._lock:
self.events.add(event)
super().clear()
def deadline(self):
deadline = 0
for event in self.events:
deadline = max(event.deadline, deadline)
return None if deadline == ETERNITY else deadline
def wait(self, timeout=None):
"""wait for all events being set or timed out"""
if not self.events: # do not wait if events are empty
return True
deadline = self.deadline()
if deadline is not None:
deadline -= time.monotonic()
timeout = deadline if timeout is None else min(deadline, timeout)
if timeout <= 0:
return False
return super().wait(timeout)
def waiting_for(self):
return set(event.name for event in self.events)
def get_trigger(self, timeout=None, name=None):
"""create a new single event and return its set method
as a convenience method
"""
return self.new(timeout, name).set
def queue(self, action):
"""add an action to the queue of actions to be executed at end
:param action: a function, to be executed after the last event is triggered,
and before the multievent is set
- if no events are waiting, the actions are executed immediately
- if an action raises an exception, it is silently ignore and further
actions in the queue are skipped
- if this is not desired, the action should handle errors by itself
"""
with self._lock:
self._actions.append(action)
if self.is_set():
self.set_(None)