L2SS-398: improve subscribers handling

devices/toolkit/archiver.py

@@ -2,8 +2,6 @@
 
 #from logging import raiseExceptions
 import logging
-import traceback
-from clients.attribute_wrapper import attribute_wrapper
 from tango import DeviceProxy, AttributeProxy
 from datetime import datetime, timedelta
 
@@ -30,6 +28,20 @@ def parse_attribute_name(attribute_name:str):
         else:
             return attribute_name
 
+def parse_device_name(device_name:str, tango_host:str = 'databaseds:10000'):
+    """
+    For some operations Tango devices must be transformed from the form 'domain/family/name'
+    to 'tango://db:port/domain/family/name'
+    """
+    chunk_num = len(device_name.split('/'))
+    if (chunk_num==3):
+        return 'tango://'+tango_host+'/'+device_name
+    elif (chunk_num==6 and device_name.split('/')[0]=='tango:'):
+        return device_name
+    else:
+        raise Exception(f'{device_name} is a wrong device name')
+    
+
 class Archiver():
     """
     The Archiver class implements the basic operations to perform attributes archiving
@@ -48,7 +60,7 @@ class Archiver():
                 raise Exception("Configuration Manager is in FAULT state")
         except Exception as e:
             raise Exception("Connection failed with Configuration Manager device") from e
-        self.es_list = [es_name for es_name in self.get_subscribers(from_db=True)] or []
+        self.es_list = [es_name for es_name in self.get_subscribers(from_db=False)] or []
         self.cm.write_attribute('Context',context)    # Set default Context Archiving for all the subscribers
         self.selector = Selector() if selector_filename is None else Selector(selector_filename)  # Create selector for customized strategies
         try:
@@ -56,21 +68,33 @@ class Archiver():
         except Exception as e:
             raise Exception("Error in selecting configuration! Archiving framework will not be updated!") from e
     
-    def get_hdbpp_libname(self, device_name:str):
+    def get_db_config(self, device_name:str):
         """
-        Get the hdbpp library name used by the Configuration Manager or by the EventSubscribers
-        Useful in the case of different DBMS architectures (e.g. MySQL, TimescaleDB)
+        Retrieve the DB credentials from the Tango properties of Configuration Manager or EventSubscribers
         """
         device = DeviceProxy(device_name)
         config_list = device.get_property('LibConfiguration')['LibConfiguration'] # dictionary {'LibConfiguration': list of strings}
+        host = str([s for s in config_list if "host" in s][0].split('=')[1])
         libname = str([s for s in config_list if "libname" in s][0].split('=')[1])
-        return libname
+        dbname = str([s for s in config_list if "dbname" in s][0].split('=')[1])
+        port = str([s for s in config_list if "port" in s][0].split('=')[1])
+        user = str([s for s in config_list if "user" in s][0].split('=')[1])
+        pw = str([s for s in config_list if "password" in s][0].split('=')[1])
+        return [host,libname,dbname,port,user,pw]
     
-    def get_subscribers(self, from_db:bool=True):
+    def get_hdbpp_libname(self, device_name:str):
+        """
+        Get the hdbpp library name used by the Configuration Manager or by the EventSubscribers
+        Useful in the case of different DBMS architectures (e.g. MySQL, TimescaleDB)
+        """
+        config_list = self.get_db_config(device_name)
+        return config_list[1]
+    
+    def get_subscribers(self, from_db:bool=False):
         """
         Get the list of Event Subscribers managed by the Configuration Manager.
         It can be retrieved as a device property (stored in TangoDB) or as a device attribute.
-        The first option seems to be the safest one.
+        Choose from_db=True only if new subscribers are not added dynamically while ConfManager is running.
         """
         if from_db:
             es_list = self.cm.get_property('ArchiverList')['ArchiverList'] or []
@@ -84,7 +108,19 @@ class Archiver():
         TODO: the choice among subscribers should be done analysing their load
         """
         es_list = self.get_subscribers()
+        # Only one subscriber in ConfManager list
+        if len(es_list)==1:
             return es_list[0]
+        else :
+            # Choose the best subscriber analysing their load
+            load_dict = {}
+            for es_name in es_list:
+                es = DeviceProxy(es_name)
+                load_dict[es_name]=float(es.AttributeRecordFreq)
+            min_load = min(load_dict.values())
+            # Return the subscriber's name with min load
+            min_es = list(load_dict.keys())[list(load_dict.values()).index(min_load)]
+            return min_es     
     
     def apply_selector(self):
         """
@@ -127,6 +163,23 @@ class Archiver():
                     raise Exception from e                              
         return env_dict
     
+    def add_event_subscriber(self, es_name:str=None):
+        """
+        Add an additional Event Subscriber to the Configuration Manager
+        """
+        # If the subscriber name is not defined, generate the name by incrementing the existing one
+        if es_name is None:
+            last_es_name = self.get_subscribers()[-1]
+            last_es_idx = int(last_es_name[-2:])
+            es_name = last_es_name[:-2]+'0'+str(last_es_idx+1)
+        try:
+            self.cm.ArchiverAdd(parse_device_name(es_name))
+        except Exception as e:
+            if 'already_present' in str(e):
+                logger.warning(f"Subscriber {es_name} already present in Configuration Manager")
+            else:
+                raise Exception from e
+
     def add_attribute_to_archiver(self, attribute_name: str, polling_period: int, event_period: int, strategy: str = 'RUN', es_name:str=None):
         """
         Takes as input the attribute name, polling period (ms), event period (ms) and archiving strategy,