experimental persistent mixin

- still contains changes in mouduls/params ...

secop/modules.py

@@ -24,13 +24,15 @@
 
 
 import sys
+import os
+import json
 import time
 
 from secop.datatypes import ArrayOf, BoolType, EnumType, FloatRange, \
     IntRange, StatusType, StringType, TextType, TupleOf, get_datatype
 from secop.errors import BadValueError, ConfigError, InternalError, \
     ProgrammingError, SECoPError, SilentError, secop_error
-from secop.lib import formatException, mkthread
+from secop.lib import formatException, getGeneralConfig, mkthread
 from secop.lib.enum import Enum
 from secop.params import Accessible, Command, Parameter
 from secop.poller import BasicPoller, Poller
@@ -240,6 +242,8 @@ class Module(HasAccessibles):
         self.name = name
         self.valueCallbacks = {}
         self.errorCallbacks = {}
+        self.persistentFile = None
+        self.persistentData = {}
         errors = []
 
         # handle module properties
@@ -385,7 +389,7 @@ class Module(HasAccessibles):
                 if k in self.parameters or k in self.propertyDict:
                     setattr(self, k, v)
                     cfgdict.pop(k)
-            except (ValueError, TypeError):
+            except (ValueError, TypeError) as e:
                 # self.log.exception(formatExtendedStack())
                 errors.append('module %s, parameter %s: %s' % (self.name, k, e))
 
@@ -395,6 +399,8 @@ class Module(HasAccessibles):
             if '$' in dt.unit:
                 dt.setProperty('unit', dt.unit.replace('$', self.parameters['value'].datatype.unit))
 
+        self.writeDict.update(self.loadParameters())
+
         # 6) check complete configuration of * properties
         if not errors:
             try:
@@ -533,6 +539,7 @@ class Module(HasAccessibles):
                     self.log.error(str(e))
                 except Exception:
                     self.log.error(formatException())
+        self.saveParameters()
         if started_callback:
             started_callback()
 
@@ -545,6 +552,60 @@ class Module(HasAccessibles):
         """
         mkthread(self.writeInitParams, started_callback)
 
+    def loadParameters(self):
+        """load persistent parameters
+
+        :return: persistent parameters which have to be written
+
+        is called upon startup and may be called from a module
+        when a hardware powerdown is detected
+        """
+        if any(pobj.persistent for pobj in self.parameters.values()):
+            persistentdir = os.path.join(getGeneralConfig()['logdir'], 'persistent')
+            self.persistentFile = os.path.join(persistentdir, '%s.%s.json' % (self.DISPATCHER.equipment_id, self.name))
+        else:
+            self.persistentFile = None
+            return {}
+        try:
+            with open(self.persistentFile, 'r') as f:
+                self.persistentData = json.load(f)
+        except FileNotFoundError:
+            self.persistentData = {}
+        writeDict = {}
+        for pname, pobj in self.parameters.items():
+            if pobj.persistent and pname in self.persistentData:
+                value = pobj.datatype.import_value(self.persistentData[pname])
+                try:
+                    pobj.value = value
+                    if not pobj.readonly:
+                        writeDict[pname] = value
+                except Exception as e:
+                    self.log.warning('can not restore %r to %r (%r)' % (pname, value, e))
+        return writeDict
+
+    def saveParameters(self):
+        """save persistent parameters
+
+        to be called regularely explicitly by the module
+        """
+        data = {k: v.export_value() for k, v in self.parameters.items() if v.persistent}
+        if data != self.persistentData:
+            self.persistentData = data
+            persistentdir = os.path.basename(self.persistentFile)
+            tmpfile = self.persistentFile + '.tmp'
+            if not os.path.isdir(persistentdir):
+                os.makedirs(persistentdir, exist_ok=True)
+            try:
+                with open(tmpfile, 'w') as f:
+                    json.dump(self.persistentData, f, indent=2)
+                    f.write('\n')
+                os.rename(tmpfile, self.persistentFile)
+            finally:
+                try:
+                    os.remove(tmpfile)
+                except FileNotFoundError:
+                    pass
+
 
 class Readable(Module):
     """basic readable module"""