1 files changed, 58 insertions, 45 deletions

diff --git a/synapse/types.py b/synapse/types.py
index 9ac688b2..0586d2cb 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -24,6 +24,7 @@ from typing import (
     Mapping,
     Match,
     MutableMapping,
+    NoReturn,
     Optional,
     Set,
     Tuple,
@@ -35,7 +36,8 @@ from typing import (
 import attr
 from frozendict import frozendict
 from signedjson.key import decode_verify_key_bytes
-from typing_extensions import TypedDict
+from signedjson.types import VerifyKey
+from typing_extensions import Final, TypedDict
 from unpaddedbase64 import decode_base64
 from zope.interface import Interface
 
@@ -55,6 +57,7 @@ from synapse.util.stringutils import parse_and_validate_server_name
 if TYPE_CHECKING:
     from synapse.appservice.api import ApplicationService
     from synapse.storage.databases.main import DataStore, PurgeEventsStore
+    from synapse.storage.databases.main.appservice import ApplicationServiceWorkerStore
 
 # Define a state map type from type/state_key to T (usually an event ID or
 # event)
@@ -114,7 +117,7 @@ class Requester:
     app_service: Optional["ApplicationService"]
     authenticated_entity: str
 
-    def serialize(self):
+    def serialize(self) -> Dict[str, Any]:
         """Converts self to a type that can be serialized as JSON, and then
         deserialized by `deserialize`
 
@@ -132,7 +135,9 @@ class Requester:
         }
 
     @staticmethod
-    def deserialize(store, input):
+    def deserialize(
+        store: "ApplicationServiceWorkerStore", input: Dict[str, Any]
+    ) -> "Requester":
         """Converts a dict that was produced by `serialize` back into a
         Requester.
 
@@ -236,10 +241,10 @@ class DomainSpecificString(metaclass=abc.ABCMeta):
     domain: str
 
     # Because this is a frozen class, it is deeply immutable.
-    def __copy__(self):
+    def __copy__(self: DS) -> DS:
         return self
 
-    def __deepcopy__(self, memo):
+    def __deepcopy__(self: DS, memo: Dict[str, object]) -> DS:
         return self
 
     @classmethod
@@ -315,29 +320,6 @@ class EventID(DomainSpecificString):
     SIGIL = "$"
 
 
-@attr.s(slots=True, frozen=True, repr=False)
-class GroupID(DomainSpecificString):
-    """Structure representing a group ID."""
-
-    SIGIL = "+"
-
-    @classmethod
-    def from_string(cls: Type[DS], s: str) -> DS:
-        group_id: DS = super().from_string(s)  # type: ignore
-
-        if not group_id.localpart:
-            raise SynapseError(400, "Group ID cannot be empty", Codes.INVALID_PARAM)
-
-        if contains_invalid_mxid_characters(group_id.localpart):
-            raise SynapseError(
-                400,
-                "Group ID can only contain characters a-z, 0-9, or '=_-./'",
-                Codes.INVALID_PARAM,
-            )
-
-        return group_id
-
-
 mxid_localpart_allowed_characters = set(
     "_-./=" + string.ascii_lowercase + string.digits
 )
@@ -625,6 +607,22 @@ class RoomStreamToken:
             return "s%d" % (self.stream,)
 
 
+class StreamKeyType:
+    """Known stream types.
+
+    A stream is a list of entities ordered by an incrementing "stream token".
+    """
+
+    ROOM: Final = "room_key"
+    PRESENCE: Final = "presence_key"
+    TYPING: Final = "typing_key"
+    RECEIPT: Final = "receipt_key"
+    ACCOUNT_DATA: Final = "account_data_key"
+    PUSH_RULES: Final = "push_rules_key"
+    TO_DEVICE: Final = "to_device_key"
+    DEVICE_LIST: Final = "device_list_key"
+
+
 @attr.s(slots=True, frozen=True, auto_attribs=True)
 class StreamToken:
     """A collection of keys joined together by underscores in the following
@@ -641,7 +639,7 @@ class StreamToken:
         6. `push_rules_key`: `541479`
         7. `to_device_key`: `274711`
         8. `device_list_key`: `265584`
-        9. `groups_key`: `1`
+        9. `groups_key`: `1` (note that this key is now unused)
 
     You can see how many of these keys correspond to the various
     fields in a "/sync" response:
@@ -693,6 +691,7 @@ class StreamToken:
     push_rules_key: int
     to_device_key: int
     device_list_key: int
+    # Note that the groups key is no longer used and may have bogus values.
     groups_key: int
 
     _SEPARATOR = "_"
@@ -724,21 +723,26 @@ class StreamToken:
                 str(self.push_rules_key),
                 str(self.to_device_key),
                 str(self.device_list_key),
+                # Note that the groups key is no longer used, but it is still
+                # serialized so that there will not be confusion in the future
+                # if additional tokens are added.
                 str(self.groups_key),
             ]
         )
 
     @property
-    def room_stream_id(self):
+    def room_stream_id(self) -> int:
         return self.room_key.stream
 
-    def copy_and_advance(self, key, new_value) -> "StreamToken":
+    def copy_and_advance(self, key: str, new_value: Any) -> "StreamToken":
         """Advance the given key in the token to a new value if and only if the
         new value is after the old value.
+
+        :raises TypeError: if `key` is not the one of the keys tracked by a StreamToken.
         """
-        if key == "room_key":
+        if key == StreamKeyType.ROOM:
             new_token = self.copy_and_replace(
-                "room_key", self.room_key.copy_and_advance(new_value)
+                StreamKeyType.ROOM, self.room_key.copy_and_advance(new_value)
             )
             return new_token
 
@@ -751,7 +755,7 @@ class StreamToken:
         else:
             return self
 
-    def copy_and_replace(self, key, new_value) -> "StreamToken":
+    def copy_and_replace(self, key: str, new_value: Any) -> "StreamToken":
         return attr.evolve(self, **{key: new_value})
 
 
@@ -793,14 +797,14 @@ class ThirdPartyInstanceID:
     # Deny iteration because it will bite you if you try to create a singleton
     # set by:
     #    users = set(user)
-    def __iter__(self):
+    def __iter__(self) -> NoReturn:
         raise ValueError("Attempted to iterate a %s" % (type(self).__name__,))
 
     # Because this class is a frozen class, it is deeply immutable.
-    def __copy__(self):
+    def __copy__(self) -> "ThirdPartyInstanceID":
         return self
 
-    def __deepcopy__(self, memo):
+    def __deepcopy__(self, memo: Dict[str, object]) -> "ThirdPartyInstanceID":
         return self
 
     @classmethod
@@ -852,25 +856,28 @@ class DeviceListUpdates:
         return bool(self.changed or self.left)
 
 
-def get_verify_key_from_cross_signing_key(key_info):
+def get_verify_key_from_cross_signing_key(
+    key_info: Mapping[str, Any]
+) -> Tuple[str, VerifyKey]:
     """Get the key ID and signedjson verify key from a cross-signing key dict
 
     Args:
-        key_info (dict): a cross-signing key dict, which must have a "keys"
+        key_info: a cross-signing key dict, which must have a "keys"
             property that has exactly one item in it
 
     Returns:
-        (str, VerifyKey): the key ID and verify key for the cross-signing key
+        the key ID and verify key for the cross-signing key
     """
-    # make sure that exactly one key is provided
+    # make sure that a `keys` field is provided
     if "keys" not in key_info:
         raise ValueError("Invalid key")
     keys = key_info["keys"]
-    if len(keys) != 1:
-        raise ValueError("Invalid key")
-    # and return that one key
-    for key_id, key_data in keys.items():
+    # and that it contains exactly one key
+    if len(keys) == 1:
+        key_id, key_data = next(iter(keys.items()))
         return key_id, decode_verify_key_bytes(key_id, decode_base64(key_data))
+    else:
+        raise ValueError("Invalid key")
 
 
 @attr.s(auto_attribs=True, frozen=True, slots=True)
@@ -906,3 +913,9 @@ class UserProfile(TypedDict):
     user_id: str
     display_name: Optional[str]
     avatar_url: Optional[str]
+
+
+@attr.s(auto_attribs=True, frozen=True, slots=True)
+class RetentionPolicy:
+    min_lifetime: Optional[int] = None
+    max_lifetime: Optional[int] = None