Merge pull request #1615 from catunlock/dependent_elements

Udef checks dependencies

src/sardana/macroserver/macros/test/test_scanct.py

@@ -24,6 +24,7 @@
 ##############################################################################
 
 """Tests for continuous scans (ct-like)"""
+import json
 import time
 import PyTango
 import unittest
@@ -343,6 +344,8 @@ def macro_stops(self, meas_config, macro_params, wait_timeout=None,
         ScanctTest.check_stopped(self)
 
     def tearDown(self):
+        for mg in self.pool.MotorGroupList:
+            self.pool.DeleteElement(json.loads(mg)['name'])
         ScanctTest.tearDown(self)
         unittest.TestCase.tearDown(self)
 
@@ -398,5 +401,7 @@ def macro_stops(self, meas_config, macro_params, wait_timeout=None,
         ScanctTest.check_stopped(self)
 
     def tearDown(self):
+        for mg in self.pool.MotorGroupList:
+            self.pool.DeleteElement(json.loads(mg)['name'])
         ScanctTest.tearDown(self)
         unittest.TestCase.tearDown(self)

src/sardana/pool/pool.py

@@ -32,6 +32,7 @@
 
 __docformat__ = 'restructuredtext'
 
+import gc
 import os.path
 import logging.handlers
 
@@ -559,8 +560,25 @@ def delete_element(self, name):
                 elem = self.get_element(full_name=name)
             except:
                 raise Exception("There is no element with name '%s'" % name)
-
-        elem_type = elem.get_type()
+
+        # cycle-reference may exist between the element and a traceback
+        # stored in SardanaValue or SardanaAttribute as a consequence of
+        # getting sys.exc_info() - try to delete them with gc.collect()
+        if elem.has_dependent_elements():
+            gc.collect()
+
+        dependent_elements = elem.get_dependent_elements()
+        if len(dependent_elements) > 0:
+            names = [elem.name for elem in dependent_elements]
+            raise Exception(
+                "The element {} can't be deleted because {} depend on it."
+                "\n\nIf the name of the dependent element starts with " 
+                "'_mg_ms_*' it means that are motor groups, execute "
+                "DeleteElement(<motor_group_name>) command on the Pool e.g. "
+                "Pool_demo1_1.DeleteElement('_mg_ms_20671_1') in Spock."
+                .format(name, ", ".join(names)))
+
+        elem_type = elem.get_type()    
         if elem_type == ElementType.Controller:
             if len(elem.get_elements()) > 0:
                 raise Exception("Cannot delete controller with elements. "

src/sardana/pool/poolacquisition.py

@@ -561,7 +561,7 @@ def run(self, *args, **kwargs):
             # clean also the pseudo counters, even the ones that do not
             # participate directly in the acquisition
             for pseudo_elem in elem.get_pseudo_elements():
-                pseudo_elem.clear_value_buffer()
+                pseudo_elem().clear_value_buffer()
 
         if self._hw_acq_args is not None:
             self._hw_acq._wait()

src/sardana/pool/poolbasechannel.py

@@ -30,6 +30,8 @@
 
 __docformat__ = 'restructuredtext'
 
+import weakref
+
 from sardana.sardanadefs import AttrQuality, ElementType
 from sardana.sardanaattribute import SardanaAttribute
 from sardana.sardanabuffer import SardanaBuffer
@@ -41,6 +43,7 @@
 from sardana.sardanaevent import EventType
 from sardana.pool import AcqSynch, AcqMode
 
+
 class ValueBuffer(SardanaBuffer):
 
     def is_value_required(self, idx):
@@ -53,7 +56,7 @@ def is_value_required(self, idx):
         :rtype: bool
         """
         for element in self.obj.get_pseudo_elements():
-            if element.get_value_buffer().next_idx <= idx:
+            if element().get_value_buffer().next_idx <= idx:
                 return True
         return False
 
@@ -135,8 +138,8 @@ def get_pseudo_elements(self):
         """Returns list of pseudo elements e.g. pseudo counters that this
         channel belongs to.
 
-        :return: pseudo elements
-        :rtype: seq<:class:`~sardana.pool.poolpseudocounter.PoolPseudoCounter`>
+        :return: weak references to pseudo elements
+        :rtype: seq<:class:`weakref.ref`>
         """
         return self._pseudo_elements
 
@@ -150,7 +153,7 @@ def add_pseudo_element(self, element):
         """
         if not self.has_pseudo_elements():
             self.get_value_buffer().persistent = True
-        self._pseudo_elements.append(element)
+        self._pseudo_elements.append(weakref.ref(element))
 
     def remove_pseudo_element(self, element):
         """Removes pseudo element e.g. pseudo counters that this channel
@@ -160,10 +163,17 @@ def remove_pseudo_element(self, element):
         :type element:
             :class:`~sardana.pool.poolpseudocounter.PoolPseudoCounter`
         """
-
-        self._pseudo_elements.remove(element)
-        if not self.has_pseudo_elements():
-            self.get_value_buffer().persistent = False
+        for pseudo_element in self._pseudo_elements:
+            if pseudo_element() == element:
+                self._pseudo_elements.remove(pseudo_element)
+                if not self.has_pseudo_elements():
+                    self.get_value_buffer().persistent = False
+                break
+        else:
+            raise ValueError(
+                "{} is not a pseudo element of {}".format(
+                    element.name, self.name)
+            )
 
     def get_value_attribute(self):
         """Returns the value attribute object for this experiment channel

src/sardana/pool/poolbaseelement.py

@@ -100,6 +100,12 @@ def serialize(self, *args, **kwargs):
         ret = PoolObject.serialize(self, *args, **kwargs)
         return ret
 
+    def get_dependent_elements(self):
+        return []
+
+    def has_dependent_elements(self):
+        return False
+
     # --------------------------------------------------------------------------
     # simulation mode
     # --------------------------------------------------------------------------

src/sardana/pool/poolcontroller.py

@@ -442,10 +442,10 @@ def set_operator(self, operator):
 
            :param operator: the new operator object
            :type operator: object"""
-        self._operator = operator
+        self._operator = weakref.ref(operator)
 
     def get_operator(self):
-        return self._operator
+        return self._operator()
 
     operator = property(fget=get_operator, fset=set_operator,
                         doc="current controller operator")

src/sardana/pool/poolelement.py

@@ -88,6 +88,29 @@ def set_action_cache(self, action_cache):
     def get_source(self):
         return "{0}/{1}".format(self.full_name, self.get_default_acquisition_channel())
 
+    def get_dependent_elements(self):
+        """Get elements which depend on this element.
+        
+        Get elements e.g. pseudo elements or groups, which depend on this
+        element.
+        
+        :return: dependent elements
+        :rtype: seq<sardana.pool.poolbaseelement.PoolBaseElement>
+        """
+        dependent_elements = []
+        for listener in self.get_listeners():
+            try:
+                elem = listener().__self__
+            except AttributeError:
+                continue
+            if isinstance(elem, PoolBaseElement):
+                dependent_elements.append(elem)
+
+        return dependent_elements
+
+    def has_dependent_elements(self):
+        return len(self.get_dependent_elements()) > 0
+
     # --------------------------------------------------------------------------
     # instrument
     # --------------------------------------------------------------------------

src/sardana/pool/poolmeasurementgroup.py

@@ -800,7 +800,12 @@ def set_configuration_from_user(self, cfg):
                     params['pool'] = pool
                     channel = PoolExternalObject(**params)
                 else:
-                    channel = pool.get_element_by_full_name(ch_name)
+                    try:
+                        channel = pool.get_element_by_full_name(ch_name)
+                    except KeyError:
+                        raise ValueError(
+                            '{} is not defined'.format(ch_data['name']))
+
                 ch_data = self._fill_channel_data(channel, ch_data)
                 user_config_channel[ch_name] = ch_data
                 ch_item = ChannelConfiguration(channel, ch_data)
@@ -958,7 +963,11 @@ def set_configuration_from_user(self, cfg):
             for conf_synch in conf_synch_ctrl.get_channels(enabled=True):
                 user_elem_ids_list.append(conf_synch.id)
         self._parent.set_user_element_ids(user_elem_ids_list)
-
+        # force assignment of user elements to the measurement group
+        # in order to update the list of dependent elements (listeners)
+        # of the element e.g. to prevent undefinition of an element added
+        # to the measurement group.
+        self._parent.get_user_elements()
         self.changed = True
 
     def _fill_channel_data(self, channel, channel_data):
@@ -1352,16 +1361,13 @@ def prepare(self):
         value = self._get_value()
         self._pending_starts = self.nb_starts
 
-        kwargs = {'head': self}
-
         self.acquisition.prepare(self.configuration,
                                  self.acquisition_mode,
                                  value,
                                  self._synch_description,
                                  self._moveable_obj,
                                  self.sw_synch_initial_domain,
-                                 self.nb_starts,
-                                 **kwargs)
+                                 self.nb_starts)
 
     def start_acquisition(self, value=None):
         """Start measurement.

src/sardana/sardanaevent.py

@@ -105,6 +105,9 @@ def has_listeners(self):
             return False
         return len(self._listeners) > 0
 
+    def get_listeners(self):
+        return self._listeners
+
     def fire_event(self, event_type, event_value, listeners=None):
         self.flush_queue()
         self._fire_event(event_type, event_value, listeners=listeners)

src/sardana/tango/pool/Controller.py

@@ -72,6 +72,7 @@ def set_ctrl(self, ctrl):
     @DebugIt()
     def delete_device(self):
         PoolDevice.delete_device(self)
+        self.ctrl = None
 
     @DebugIt()
     def init_device(self):

src/sardana/tango/pool/MeasurementGroup.py

@@ -68,6 +68,7 @@ def delete_device(self):
         mg = self.measurement_group
         if mg is not None:
             mg.remove_listener(self.on_measurement_group_changed)
+        self.measurement_group = None
 
     @DebugIt()
     def init_device(self):

src/sardana/tango/pool/MotorGroup.py

@@ -70,6 +70,7 @@ def delete_device(self):
         motor_group = self.motor_group
         if motor_group is not None:
             motor_group.remove_listener(self.on_motor_group_changed)
+        self.motor_group = None
 
     @DebugIt()
     def init_device(self):

src/sardana/tango/pool/PseudoCounter.py

@@ -71,6 +71,7 @@ def delete_device(self):
         pseudo_counter = self.pseudo_counter
         if pseudo_counter is not None:
             pseudo_counter.remove_listener(self.on_pseudo_counter_changed)
+        self.pseudo_counter = None
 
     @DebugIt()
     def init_device(self):

src/sardana/tango/pool/PseudoMotor.py

@@ -73,6 +73,7 @@ def delete_device(self):
         pseudo_motor = self.pseudo_motor
         if pseudo_motor is not None:
             pseudo_motor.remove_listener(self.on_pseudo_motor_changed)
+        self.pseudo_motor = None
 
     @DebugIt()
     def init_device(self):