backport fixes from MLZ repo

- unification of secop.stringio/bytesio to secop.io
- persistent parameters

Change-Id: I76307cccc5191ac8cbb5cfec6fb7450fcf6945f1

secop/persistent.py

@@ -24,15 +24,14 @@
 For hardware not keeping parameters persistent, we might want to store them in Frappy.
 
 The following example will make 'param1' and 'param2' persistent, i.e. whenever
-one of the parameters is changed, either by a change command or by access from
-an other interface to the hardware, it is saved to a file, and reloaded after
+one of the parameters is changed, either by a change command or when reading back
+from the hardware, it is saved to a file, and reloaded after
 a power down / power up cycle. In order to make this work properly, there is a
 mechanism needed to detect power down (i.e. a reading a hardware parameter
 taking a special value on power up).
 
-An additional use might be the example of a motor with cyclic reading of an
-encoder value, which looses the counts of how many turns already happened on
-power down.
+An additional use might be the example of a motor with an encoder which looses
+the counts of how many turns already happened on power down.
 This can be solved by comparing the loaded encoder value self.encoder with a
 fresh value from the hardware and then adjusting the zero point accordingly.
 
@@ -56,8 +55,6 @@ class MyClass(PersistentMixin, ...):
 import os
 import json
 
-from secop.errors import BadValueError, ConfigError, InternalError, \
-    ProgrammingError, SECoPError, SilentError, secop_error
 from secop.lib import getGeneralConfig
 from secop.params import Parameter, Property, BoolType, Command
 from secop.modules import HasAccessibles
@@ -70,14 +67,15 @@ class PersistentParam(Parameter):
 class PersistentMixin(HasAccessibles):
     def __init__(self, *args, **kwds):
         super().__init__(*args, **kwds)
-        # write=False: write will happen later
+        persistentdir = os.path.join(getGeneralConfig()['logdir'], 'persistent')
+        os.makedirs(persistentdir, exist_ok=True)
+        self.persistentFile = os.path.join(persistentdir, '%s.%s.json' % (self.DISPATCHER.equipment_id, self.name))
         self.initData = {}
         for pname in self.parameters:
             pobj = self.parameters[pname]
             if not pobj.readonly and getattr(pobj, 'persistent', False):
                 self.initData[pname] = pobj.value
         self.writeDict.update(self.loadParameters(write=False))
-        print('initData', self.initData)
 
     def loadParameters(self, write=True):
         """load persistent parameters
@@ -87,8 +85,6 @@ class PersistentMixin(HasAccessibles):
         is called upon startup and may be called from a module
         when a hardware powerdown is detected
         """
-        persistentdir = os.path.join(getGeneralConfig()['logdir'], 'persistent')
-        self.persistentFile = os.path.join(persistentdir, '%s.%s.json' % (self.DISPATCHER.equipment_id, self.name))
         try:
             with open(self.persistentFile, 'r') as f:
                 self.persistentData = json.load(f)
@@ -140,8 +136,7 @@ class PersistentMixin(HasAccessibles):
                 except FileNotFoundError:
                     pass
 
-
     @Command()
     def factory_reset(self):
-         self.writeDict.update(self.initData)
-         self.writeInitParams()
+        self.writeDict.update(self.initData)
+        self.writeInitParams()