beremiz

Proper fix for error 'object has no attribute 'getSlave' in EtherCAT extension

2018-08-24, Andrey Skvortsov
96ca6b056c55
Proper fix for error 'object has no attribute 'getSlave' in EtherCAT extension

traceback:
File "/home/developer/WorkData/PLC/beremiz/beremiz/IDEFrame.py", line 1433, in OnPouSelectedChanged
window.RefreshView()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 837, in RefreshView
self.RefreshProcessVariables()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 886, in RefreshProcessVariables
slaves = self.Controler.GetSlaves(**self.CurrentNodesFilter)
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/EthercatMaster.py", line 341, in GetSlaves
for slave in self.Config.getConfig().getSlave():
:_'lxml.etree._Element'_object_has_no_attribute_'getSlave'

Steps to reproduce problem:

- Add new EtherCAT master
- Add new EthercatNode to the master
- double click on


Revert commit "Dirty fix for error '_object_has_no_attribute_'getSlave' in EtherCAT extension"
[a3ac46366b86a0b237dac93be6b2281ac70b98a8].

The problem was that XML elements (proxy object) in some cases were created using custom XML
classes constructors and lxml.etree.Element() call and live python
patching. This causes that lxml backend doesn't know that custom python class
should be used for these XML elements.
Proxy object can be move/deleted and recreated by lxml
backend at any point in time or this can be done in python by copy/deepcopy operations.
If this happens, then newly created
proxy elements are using default class lxml.etree._Element. And all
custom functionality is lost.

All created XML elements should be always created through corresponding
parser and class lookup callback done by lxml backend.
It's described in more details in lxml documentation:
https://lxml.de/element_classes.html
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# This file is part of Beremiz, a Integrated Development Environment for
# programming IEC 61131-3 automates supporting plcopen standard and CanFestival.
#
# Copyright (C) 2007: Edouard TISSERANT and Laurent BESSARD
#
# See COPYING file for copyrights details.
#
# 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
from __future__ import absolute_import
import os
import sys
import subprocess
import ctypes
from threading import Timer, Lock, Thread, Semaphore
import signal
class outputThread(Thread):
"""
Thread is used to print the output of a command to the stdout
"""
def __init__(self, Proc, fd, callback=None, endcallback=None):
Thread.__init__(self)
self.killed = False
self.finished = False
self.retval = None
self.Proc = Proc
self.callback = callback
self.endcallback = endcallback
self.fd = fd
def run(self):
outchunk = None
self.retval = None
while self.retval is None and not self.killed:
if self.endcallback:
self.retval = self.Proc.poll()
else:
self.retval = self.Proc.returncode
outchunk = self.fd.readline()
if self.callback:
self.callback(outchunk)
while outchunk != '' and not self.killed:
outchunk = self.fd.readline()
if self.callback:
self.callback(outchunk)
if self.endcallback:
try:
err = self.Proc.wait()
except Exception:
err = self.retval
self.finished = True
self.endcallback(self.Proc.pid, err)
class ProcessLogger(object):
def __init__(self, logger, Command, finish_callback=None,
no_stdout=False, no_stderr=False, no_gui=True,
timeout=None, outlimit=None, errlimit=None,
endlog=None, keyword=None, kill_it=False, cwd=None,
encoding=None, output_encoding=None):
self.logger = logger
if not isinstance(Command, list):
self.Command_str = Command
self.Command = []
for i, word in enumerate(Command.replace("'", '"').split('"')):
if i % 2 == 0:
word = word.strip()
if len(word) > 0:
self.Command.extend(word.split())
else:
self.Command.append(word)
else:
self.Command = Command
self.Command_str = subprocess.list2cmdline(self.Command)
fsencoding = sys.getfilesystemencoding()
self.output_encoding = output_encoding
if encoding is None:
encoding = fsencoding
self.Command = [self.Command[0].encode(fsencoding)]+map(
lambda x: x.encode(encoding), self.Command[1:])
self.finish_callback = finish_callback
self.no_stdout = no_stdout
self.no_stderr = no_stderr
self.startupinfo = None
self.errlen = 0
self.outlen = 0
self.errlimit = errlimit
self.outlimit = outlimit
self.exitcode = None
self.outdata = []
self.errdata = []
self.keyword = keyword
self.kill_it = kill_it
self.startsem = Semaphore(0)
self.finishsem = Semaphore(0)
self.endlock = Lock()
popenargs = {
"cwd": os.getcwd() if cwd is None else cwd,
"stdin": subprocess.PIPE,
"stdout": subprocess.PIPE,
"stderr": subprocess.PIPE
}
if no_gui and os.name in ("nt", "ce"):
self.startupinfo = subprocess.STARTUPINFO()
self.startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
popenargs["startupinfo"] = self.startupinfo
elif os.name == 'posix':
popenargs["shell"] = False
if timeout:
self.timeout = Timer(timeout, self.endlog)
self.timeout.start()
else:
self.timeout = None
self.Proc = subprocess.Popen(self.Command, **popenargs)
self.outt = outputThread(
self.Proc,
self.Proc.stdout,
self.output,
self.finish)
self.outt.start()
self.errt = outputThread(
self.Proc,
self.Proc.stderr,
self.errors)
self.errt.start()
self.startsem.release()
def output(self, v):
if v and self.output_encoding:
v = v.decode(self.output_encoding)
self.outdata.append(v)
self.outlen += 1
if not self.no_stdout:
self.logger.write(v)
if (self.keyword and v.find(self.keyword) != -1) or (self.outlimit and self.outlen > self.outlimit):
self.endlog()
def errors(self, v):
if v and self.output_encoding:
v = v.decode(self.output_encoding)
self.errdata.append(v)
self.errlen += 1
if not self.no_stderr:
self.logger.write_warning(v)
if self.errlimit and self.errlen > self.errlimit:
self.endlog()
def log_the_end(self, ecode, pid):
self.logger.write(self.Command_str + "\n")
self.logger.write_warning(_("exited with status {a1} (pid {a2})\n").format(a1=str(ecode), a2=str(pid)))
def finish(self, pid, ecode):
# avoid running function before start is finished
self.startsem.acquire()
self.startsem.release()
if self.timeout:
self.timeout.cancel()
self.exitcode = ecode
if self.exitcode != 0:
self.log_the_end(ecode, pid)
if self.finish_callback is not None:
self.finish_callback(self, ecode, pid)
self.errt.join()
self.finishsem.release()
def kill(self, gently=True):
# avoid running kill before start is finished
self.startsem.acquire()
self.startsem.release()
self.outt.killed = True
self.errt.killed = True
if os.name in ("nt", "ce"):
PROCESS_TERMINATE = 1
handle = ctypes.windll.kernel32.OpenProcess(PROCESS_TERMINATE, False, self.Proc.pid)
ctypes.windll.kernel32.TerminateProcess(handle, -1)
ctypes.windll.kernel32.CloseHandle(handle)
else:
if gently:
sig = signal.SIGTERM
else:
sig = signal.SIGKILL
try:
os.kill(self.Proc.pid, sig)
except Exception:
pass
self.outt.join()
self.errt.join()
def endlog(self):
if self.endlock.acquire(False):
if not self.outt.finished and self.kill_it:
self.kill()
self.finishsem.release()
def spin(self):
self.finishsem.acquire()
return [self.exitcode, "".join(self.outdata), "".join(self.errdata)]