Clear elem after parsing. Improves memory usage

exchangelib/folders.py

@@ -156,8 +156,9 @@ def from_xml(cls, elem):
         if elem is None:
             return None
         assert elem.tag == cls.response_tag(), (cls, elem.tag, cls.response_tag())
-        return cls(name=elem.get(cls.NAME_ATTR), value=elem.text)
-
+        res = cls(name=elem.get(cls.NAME_ATTR), value=elem.text)
+        elem.clear()
+        return res
 
 class ItemId(EWSElement):
     # 'id' and 'changekey' are UUIDs generated by Exchange
@@ -188,7 +189,9 @@ def from_xml(cls, elem):
         if elem is None:
             return None
         assert elem.tag == cls.response_tag(), (cls, elem.tag, cls.response_tag())
-        return cls(id=elem.get(cls.ID_ATTR), changekey=elem.get(cls.CHANGEKEY_ATTR))
+        res = cls(id=elem.get(cls.ID_ATTR), changekey=elem.get(cls.CHANGEKEY_ATTR))
+        elem.clear()
+        return res
 
     def __eq__(self, other):
         # A more efficient version of super().__eq__
@@ -266,11 +269,13 @@ def from_xml(cls, elem):
         if elem is None:
             return None
         assert elem.tag == cls.response_tag(), (cls, elem.tag, cls.response_tag())
-        return cls(
+        res = cls(
             id=elem.get(cls.ID_ATTR),
             root_id=elem.get(cls.ROOT_ID_ATTR),
             root_changekey=elem.get(cls.ROOT_CHANGEKEY_ATTR)
         )
+        elem.clear()
+        return res
 
 
 class Attachment(EWSElement):
@@ -360,6 +365,7 @@ def from_xml(cls, elem, parent_item=None):
                 # UTC, so mark them as such so EWSDateTime can still interpret the timestamps.
                 val += 'Z'
             kwargs[field_name] = xml_text_to_value(value=val, field_type=field_type)
+        elem.clear()
         return cls(parent_item=parent_item, **kwargs)
 
     def attach(self):
@@ -452,10 +458,12 @@ def from_xml(cls, elem):
         if elem is None:
             return None
         assert elem.tag == cls.response_tag(), (cls, elem.tag, cls.response_tag())
-        return cls(
+        res = cls(
             label=elem.get('Key'),
             email=elem.text or elem.get('Name'),  # Sometimes elem.text is empty. Exchange saves the same in 'Name' attr
         )
+        elem.clear()
+        return res
 
 
 class PhoneNumber(IndexedField):
@@ -487,10 +495,12 @@ def from_xml(cls, elem):
         if elem is None:
             return None
         assert elem.tag == cls.response_tag(), (cls, elem.tag, cls.response_tag())
-        return cls(
+        res = cls(
             label=elem.get('Key'),
             phone_number=elem.text,
         )
+        elem.clear()
+        return res
 
 
 class PhysicalAddress(IndexedField):
@@ -546,6 +556,7 @@ def from_xml(cls, elem):
         kwargs = dict(label=elem.get('Key'))
         for k, v in cls.SUB_FIELD_ELEMENT_NAMES.items():
             kwargs[k] = get_xml_attr(elem, '{%s}%s' % (TNS, v))
+        elem.clear()
         return cls(**kwargs)
 
 
@@ -590,12 +601,14 @@ def from_xml(cls, elem):
         if elem is None:
             return None
         assert elem.tag == cls.response_tag(), (elem.tag, cls.response_tag())
-        return cls(
+        res = cls(
             name=get_xml_attr(elem, '{%s}Name' % TNS),
             email_address=get_xml_attr(elem, '{%s}EmailAddress' % TNS),
             mailbox_type=get_xml_attr(elem, '{%s}MailboxType' % TNS),
             item_id=ItemId.from_xml(elem=elem.find(ItemId.response_tag())),
         )
+        elem.clear()
+        return res
 
     def __hash__(self):
         # Exchange may add 'mailbox_type' and 'name' on insert. We're satisfied if the item_id or email address matches.
@@ -625,12 +638,14 @@ def from_xml(cls, elem):
             return None
         assert elem.tag == cls.response_tag(), (elem.tag, cls.response_tag())
         id_elem = elem.find('{%s}Id' % TNS)
-        return cls(
+        res = cls(
             name=get_xml_attr(id_elem, '{%s}Name' % TNS),
             email_address=get_xml_attr(id_elem, '{%s}EmailAddress' % TNS),
             mailbox_type=get_xml_attr(id_elem, '{%s}MailboxType' % TNS),
             item_id=ItemId.from_xml(elem=id_elem.find(ItemId.response_tag())),
         )
+        elem.clear()
+        return res
 
 
 class ExtendedProperty(EWSElement):
@@ -813,11 +828,13 @@ def from_xml(cls, elem):
             return None
         assert elem.tag == cls.response_tag(), (cls, elem.tag, cls.response_tag())
         last_response_time = get_xml_attr(elem, '{%s}LastResponseTime' % TNS)
-        return cls(
+        res = cls(
             mailbox=Mailbox.from_xml(elem=elem.find(Mailbox.response_tag())),
             response_type=get_xml_attr(elem, '{%s}ResponseType' % TNS) or 'Unknown',
             last_response_time=EWSDateTime.from_string(last_response_time) if last_response_time else None,
         )
+        elem.clear()
+        return res
 
     @classmethod
     def set_field_xml(cls, field_elem, items, version):
@@ -1256,6 +1273,7 @@ def from_xml(cls, elem, account=None, folder=None):
                         kwargs[fieldname] = field_type.from_xml(sub_elem)
             else:
                 assert False, 'Field %s type %s not supported' % (fieldname, field_type)
+        elem.clear()
         return cls(item_id=item_id, changekey=changekey, account=account, folder=folder, **kwargs)
 
     def __eq__(self, other):
@@ -2125,6 +2143,7 @@ def from_xml(cls, elem, account=None):
         changekey = fld_id_elem.get(FolderId.CHANGEKEY_ATTR)
         display_name = get_xml_attr(elem, '{%s}DisplayName' % TNS)
         folder_class = get_xml_attr(elem, '{%s}FolderClass' % TNS)
+        elem.clear()
         return cls(account=account, name=display_name, folder_class=folder_class, folder_id=fld_id, changekey=changekey)
 
     def to_xml(self, version):