Merge branch 'develop' of github.com:matrix-org/synapse into t3chguy/default_inviter_display_name_3pid

1 files changed, 238 insertions, 21 deletions

diff --git a/synapse/events/snapshot.py b/synapse/events/snapshot.py
index e9a732ff03..368b5f6ae4 100644
--- a/synapse/events/snapshot.py
+++ b/synapse/events/snapshot.py
@@ -13,19 +13,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from six import iteritems
+
+from frozendict import frozendict
+
+from twisted.internet import defer
+
+from synapse.util.logcontext import make_deferred_yieldable, run_in_background
+
 
 class EventContext(object):
     """
     Attributes:
-        current_state_ids (dict[(str, str), str]):
-            The current state map including the current event.
-            (type, state_key) -> event_id
-
-        prev_state_ids (dict[(str, str), str]):
-            The current state map excluding the current event.
-            (type, state_key) -> event_id
-
-        state_group (int): state group id
+        state_group (int|None): state group id, if the state has been stored
+            as a state group. This is usually only None if e.g. the event is
+            an outlier.
         rejected (bool|str): A rejection reason if the event was rejected, else
             False
 
@@ -39,35 +41,250 @@ class EventContext(object):
 
         prev_state_events (?): XXX: is this ever set to anything other than
             the empty list?
+
+        _current_state_ids (dict[(str, str), str]|None):
+            The current state map including the current event. None if outlier
+            or we haven't fetched the state from DB yet.
+            (type, state_key) -> event_id
+
+        _prev_state_ids (dict[(str, str), str]|None):
+            The current state map excluding the current event. None if outlier
+            or we haven't fetched the state from DB yet.
+            (type, state_key) -> event_id
+
+        _fetching_state_deferred (Deferred|None): Resolves when *_state_ids have
+            been calculated. None if we haven't started calculating yet
+
+        _event_type (str): The type of the event the context is associated with.
+            Only set when state has not been fetched yet.
+
+        _event_state_key (str|None): The state_key of the event the context is
+            associated with. Only set when state has not been fetched yet.
+
+        _prev_state_id (str|None): If the event associated with the context is
+            a state event, then `_prev_state_id` is the event_id of the state
+            that was replaced.
+            Only set when state has not been fetched yet.
     """
 
     __slots__ = [
-        "current_state_ids",
-        "prev_state_ids",
         "state_group",
         "rejected",
-        "push_actions",
         "prev_group",
         "delta_ids",
         "prev_state_events",
         "app_service",
+        "_current_state_ids",
+        "_prev_state_ids",
+        "_prev_state_id",
+        "_event_type",
+        "_event_state_key",
+        "_fetching_state_deferred",
     ]
 
     def __init__(self):
+        self.prev_state_events = []
+        self.rejected = False
+        self.app_service = None
+
+    @staticmethod
+    def with_state(state_group, current_state_ids, prev_state_ids,
+                   prev_group=None, delta_ids=None):
+        context = EventContext()
+
         # The current state including the current event
-        self.current_state_ids = None
+        context._current_state_ids = current_state_ids
         # The current state excluding the current event
-        self.prev_state_ids = None
-        self.state_group = None
+        context._prev_state_ids = prev_state_ids
+        context.state_group = state_group
 
-        self.rejected = False
-        self.push_actions = []
+        context._prev_state_id = None
+        context._event_type = None
+        context._event_state_key = None
+        context._fetching_state_deferred = defer.succeed(None)
 
         # A previously persisted state group and a delta between that
         # and this state.
-        self.prev_group = None
-        self.delta_ids = None
+        context.prev_group = prev_group
+        context.delta_ids = delta_ids
 
-        self.prev_state_events = None
+        return context
 
-        self.app_service = None
+    @defer.inlineCallbacks
+    def serialize(self, event, store):
+        """Converts self to a type that can be serialized as JSON, and then
+        deserialized by `deserialize`
+
+        Args:
+            event (FrozenEvent): The event that this context relates to
+
+        Returns:
+            dict
+        """
+
+        # We don't serialize the full state dicts, instead they get pulled out
+        # of the DB on the other side. However, the other side can't figure out
+        # the prev_state_ids, so if we're a state event we include the event
+        # id that we replaced in the state.
+        if event.is_state():
+            prev_state_ids = yield self.get_prev_state_ids(store)
+            prev_state_id = prev_state_ids.get((event.type, event.state_key))
+        else:
+            prev_state_id = None
+
+        defer.returnValue({
+            "prev_state_id": prev_state_id,
+            "event_type": event.type,
+            "event_state_key": event.state_key if event.is_state() else None,
+            "state_group": self.state_group,
+            "rejected": self.rejected,
+            "prev_group": self.prev_group,
+            "delta_ids": _encode_state_dict(self.delta_ids),
+            "prev_state_events": self.prev_state_events,
+            "app_service_id": self.app_service.id if self.app_service else None
+        })
+
+    @staticmethod
+    def deserialize(store, input):
+        """Converts a dict that was produced by `serialize` back into a
+        EventContext.
+
+        Args:
+            store (DataStore): Used to convert AS ID to AS object
+            input (dict): A dict produced by `serialize`
+
+        Returns:
+            EventContext
+        """
+        context = EventContext()
+
+        # We use the state_group and prev_state_id stuff to pull the
+        # current_state_ids out of the DB and construct prev_state_ids.
+        context._prev_state_id = input["prev_state_id"]
+        context._event_type = input["event_type"]
+        context._event_state_key = input["event_state_key"]
+
+        context._current_state_ids = None
+        context._prev_state_ids = None
+        context._fetching_state_deferred = None
+
+        context.state_group = input["state_group"]
+        context.prev_group = input["prev_group"]
+        context.delta_ids = _decode_state_dict(input["delta_ids"])
+
+        context.rejected = input["rejected"]
+        context.prev_state_events = input["prev_state_events"]
+
+        app_service_id = input["app_service_id"]
+        if app_service_id:
+            context.app_service = store.get_app_service_by_id(app_service_id)
+
+        return context
+
+    @defer.inlineCallbacks
+    def get_current_state_ids(self, store):
+        """Gets the current state IDs
+
+        Returns:
+            Deferred[dict[(str, str), str]|None]: Returns None if state_group
+            is None, which happens when the associated event is an outlier.
+        """
+
+        if not self._fetching_state_deferred:
+            self._fetching_state_deferred = run_in_background(
+                self._fill_out_state, store,
+            )
+
+        yield make_deferred_yieldable(self._fetching_state_deferred)
+
+        defer.returnValue(self._current_state_ids)
+
+    @defer.inlineCallbacks
+    def get_prev_state_ids(self, store):
+        """Gets the prev state IDs
+
+        Returns:
+            Deferred[dict[(str, str), str]|None]: Returns None if state_group
+            is None, which happens when the associated event is an outlier.
+        """
+
+        if not self._fetching_state_deferred:
+            self._fetching_state_deferred = run_in_background(
+                self._fill_out_state, store,
+            )
+
+        yield make_deferred_yieldable(self._fetching_state_deferred)
+
+        defer.returnValue(self._prev_state_ids)
+
+    def get_cached_current_state_ids(self):
+        """Gets the current state IDs if we have them already cached.
+
+        Returns:
+            dict[(str, str), str]|None: Returns None if we haven't cached the
+            state or if state_group is None, which happens when the associated
+            event is an outlier.
+        """
+
+        return self._current_state_ids
+
+    @defer.inlineCallbacks
+    def _fill_out_state(self, store):
+        """Called to populate the _current_state_ids and _prev_state_ids
+        attributes by loading from the database.
+        """
+        if self.state_group is None:
+            return
+
+        self._current_state_ids = yield store.get_state_ids_for_group(
+            self.state_group,
+        )
+        if self._prev_state_id and self._event_state_key is not None:
+            self._prev_state_ids = dict(self._current_state_ids)
+
+            key = (self._event_type, self._event_state_key)
+            self._prev_state_ids[key] = self._prev_state_id
+        else:
+            self._prev_state_ids = self._current_state_ids
+
+    @defer.inlineCallbacks
+    def update_state(self, state_group, prev_state_ids, current_state_ids,
+                     prev_group, delta_ids):
+        """Replace the state in the context
+        """
+
+        # We need to make sure we wait for any ongoing fetching of state
+        # to complete so that the updated state doesn't get clobbered
+        if self._fetching_state_deferred:
+            yield make_deferred_yieldable(self._fetching_state_deferred)
+
+        self.state_group = state_group
+        self._prev_state_ids = prev_state_ids
+        self.prev_group = prev_group
+        self._current_state_ids = current_state_ids
+        self.delta_ids = delta_ids
+
+        # We need to ensure that that we've marked as having fetched the state
+        self._fetching_state_deferred = defer.succeed(None)
+
+
+def _encode_state_dict(state_dict):
+    """Since dicts of (type, state_key) -> event_id cannot be serialized in
+    JSON we need to convert them to a form that can.
+    """
+    if state_dict is None:
+        return None
+
+    return [
+        (etype, state_key, v)
+        for (etype, state_key), v in iteritems(state_dict)
+    ]
+
+
+def _decode_state_dict(input):
+    """Decodes a state dict encoded using `_encode_state_dict` above
+    """
+    if input is None:
+        return None
+
+    return frozendict({(etype, state_key,): v for etype, state_key, v in input})