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tests/python/python@py_ext/pyfile.xml
author Andrey Skvortsov <andrej.skvortzov@gmail.com>
Thu, 28 Apr 2016 13:05:57 +0300
changeset 1507 d7f474d10210
parent 1401 611fded24ce4
child 2680 6bfed6757495
permissions -rw-r--r--
fix issue with sometimes wrong return code of ProcessLogger


As a result of wrong return code Beremiz gives folowing traceback:
Traceback (most recent call last):
File "./Beremiz.py", line 850, in OnMenu
getattr(self.CTR, method)()
File "/home/developer/WorkData/PLC/beremiz/beremiz/ProjectController.py", line 925, in _Build
IECGenRes = self._Generate_SoftPLC()
File "/home/developer/WorkData/PLC/beremiz/beremiz/ProjectController.py", line 568, in _Generate_SoftPLC
return self._Compile_ST_to_SoftPLC()
File "/home/developer/WorkData/PLC/beremiz/beremiz/ProjectController.py", line 661, in _Compile_ST_to_SoftPLC
C_files.remove("POUS.c")
ValueError: list.remove(x): x not in list

The problem is that both threads (for reading stdout and stderr) call self.Proc.poll(),
that updates internal returncode field. This call is done without any locking and the first thread gets correct result,
but other gets 0 as retval. If 0 gets thread, that afterwards calls callback finish, then wrong return code is returned
to the parent. Now only the thread with a callback polls for the return code, other thread just checked local value.

Additionally function spin() waits now until all threads finish reading their pipes, so the results are always correct. 
<?xml version='1.0' encoding='utf-8'?>
<PyFile xmlns:xhtml="http://www.w3.org/1999/xhtml">
  <variables>
    <variable name="Test_Python_Var" type="INT" initial="4"/>
    <variable name="Second_Python_Var" type="INT" initial="5"/>
  </variables>
  <globals>
    <xhtml:p><![CDATA[
import time,sys,ctypes
Python_to_C_Call = PLCBinary.Python_to_C_Call
Python_to_C_Call.restype = ctypes.c_int
Python_to_C_Call.argtypes = [ctypes.c_int, ctypes.POINTER(ctypes.c_int)]

def MyPythonFunc(arg):
    i = ctypes.c_int()
    if(Python_to_C_Call(arg, i)):
        res = i.value
        print "toC:", arg, "from C:", res, "FBID:", FBID
    else:
        print "Failed Python_to_C_Call failed"
        res = None
    print "Python read PLC global :",PLCGlobals.Test_Python_Var
    PLCGlobals.Second_Python_Var = 789
    sys.stdout.flush()
    return res

async_error_test_code = """
def badaboom():
    tuple()[0]

import wx
def badaboomwx():
    wx.CallAfter(badaboom)

from threading import Timer
a = Timer(3, badaboom)
a.start()

b = Timer(6, badaboomwx)
b.start()
"""
]]></xhtml:p>
  </globals>
  <init>
    <xhtml:p><![CDATA[
global x, y
x = 2
y = 5
print "py_runtime init:", x, ",", y
]]></xhtml:p>
  </init>
  <cleanup>
    <xhtml:p><![CDATA[
print "py_runtime cleanup"
]]></xhtml:p>
  </cleanup>
  <start>
    <xhtml:p><![CDATA[
global x, y
print "py_runtime start", x * x + y * y
]]></xhtml:p>
  </start>
  <stop>
    <xhtml:p><![CDATA[
print "py_runtime stop"
]]></xhtml:p>
  </stop>
</PyFile>
beremiz