# by the Factory, you need to restart your python instance / web server
# as the cached information then becomes wrong
+from PLC.Logger import logger
+
from PLC.TagTypes import TagTypes, TagType
+from PLC.Roles import Roles, Role
# implementation
-class Accessor (object) :
- """This is placeholder for storing accessor-related tag checkers.
-Methods in this class are defined by the accessors factory
+class Accessor(object):
+ """
+ This is a placeholder for storing accessor-related tag checkers.
+ Methods in this class are defined by the accessors factory
-This is implemented as a singleton, so we can cache results over time"""
+ Class is implemented as a singleton, so we can cache results over time
+ """
_instance = None
- def __init__ (self, api):
- self.api=api
+ tag_locators = {}
+
+ def __init__(self, api):
+ self.api = api
# 'tagname'=>'tag_id'
- self.cache={}
+ self.cache = {}
+ self.hash_name_to_role = {role['name']: role for role in Roles(api)}
+
+ def has_cache(self, tagname):
+ return tagname in self.cache
+
+ def get_cache(self, tagname):
+ return self.cache[tagname]
- def has_cache (self,tagname): return self.cache.has_key(tagname)
- def get_cache (self,tagname): return self.cache[tagname]
- def set_cache (self,tagname,tag_id): self.cache[tagname]=tag_id
+ def set_cache(self, tagname, tag_type):
+ self.cache[tagname] = tag_type
- def locate_or_create_tag (self,tagname,category, description, min_role_id):
+ def locate_or_create_tag(self, tagname, category,
+ description, roles, enforce=False):
"search tag type from tagname & create if needed"
# cached ?
- if self.has_cache (tagname):
+ if self.has_cache(tagname):
return self.get_cache(tagname)
# search
- tag_types = TagTypes (self.api, {'tagname':tagname})
+ tag_types = TagTypes(self.api, {'tagname': tagname})
if tag_types:
tag_type = tag_types[0]
+ # enforce should only be set by
+ # 'service plc start accessors' sequence
+ if enforce:
+ try:
+ tag_type.update({'category': category,
+ 'description': description})
+ tag_type.sync()
+ roles_to_add = set(roles).difference(set(tag_type['roles']))
+ for rolename in roles_to_add:
+ tag_type.add_role(self.hash_name_to_role[rolename])
+ roles_to_delete = set(tag_type['roles']). difference(set(roles))
+ for rolename in roles_to_delete:
+ tag_type.remove_role(self.hash_name_to_role[rolename])
+ except:
+ logger.exception(
+ "WARNING, Could not enforce tag type, tagname={}\n"
+ .format(tagname))
+
+
else:
# not found: create it
- tag_type_fields = {'tagname':tagname,
- 'category' : category,
- 'description' : description,
- 'min_role_id': min_role_id}
- tag_type = TagType (self.api, tag_type_fields)
+ tag_type_fields = {'tagname': tagname,
+ 'category': category,
+ 'description': description}
+ tag_type = TagType(self.api, tag_type_fields)
tag_type.sync()
- tag_type_id = tag_type['tag_type_id']
- self.set_cache(tagname,tag_type_id)
- return tag_type_id
+ for role in roles:
+ try:
+ role_obj = Roles(self.api, role)[0]
+ tag_type.add_role(role_obj)
+ except:
+ # xxx todo find a more appropriate way of notifying this
+ logger.exception("Accessor.locate_or_create_tag: "
+ "Could not add role {} to tag_type {}"
+ .format(role,tagname))
+ self.set_cache(tagname, tag_type)
+ return tag_type
+
+ # a locator is a function that retrieves - or creates - a tag_type instance
+ @staticmethod
+ def register_tag_locator(name, tag_locator):
+ Accessor.tag_locators[name] = tag_locator
+
+ @staticmethod
+ def retrieve_tag_locator(name):
+ return Accessor.tag_locators[name]
+ # this is designed to be part of the 'service plc start' sequence
+ # it ensures the creation of all the tagtypes defined
+ # in the various accessors, and enforces consistency to the DB
+ # it's not easy to have define_accessors do this because at
+ # load-time as we do not have an instance of API yet
+ def run_all_tag_locators(self):
+ for (name, tag_locator) in list(Accessor.tag_locators.items()):
+ tag_locator(self, enforce=True)
####################
# make it a singleton so we can cache stuff in there over time
-def AccessorSingleton (api):
+def AccessorSingleton(api):
if not Accessor._instance:
Accessor._instance = Accessor(api)
return Accessor._instance