1  """
 2  Storing inventory items
 3  """
 4  
 5  from abc import abstractmethod
 6  from collections import namedtuple
 7  try:
 8      from collections import MutableMapping  # pylint: disable=deprecated-class
 9  except ImportError:
10      from collections.abc import MutableMapping
11  
12  
13  InventoryItem = namedtuple('InventoryItem', 'type stream payload expires tag')
14  
15  
16  class InventoryStorage(MutableMapping):
17      """
18      Base class for storing inventory
19      (extendable for other items to store)
20      """
21  
22      def __init__(self):
23          self.numberOfInventoryLookupsPerformed = 0
24  
25      @abstractmethod
26      def __contains__(self, item):
27          pass
28  
29      @abstractmethod
30      def by_type_and_tag(self, objectType, tag):
31          """Return objects filtered by object type and tag"""
32          pass
33  
34      @abstractmethod
35      def unexpired_hashes_by_stream(self, stream):
36          """Return unexpired inventory vectors filtered by stream"""
37          pass
38  
39      @abstractmethod
40      def flush(self):
41          """Flush cache"""
42          pass
43  
44      @abstractmethod
45      def clean(self):
46          """Free memory / perform garbage collection"""
47          pass