diff --git a/synapse/storage/state.py b/synapse/storage/state.py
index a7c3d401d4..5673e4aa96 100644
--- a/synapse/storage/state.py
+++ b/synapse/storage/state.py
@@ -20,6 +20,7 @@ from synapse.util.stringutils import to_ascii
from synapse.storage.engines import PostgresEngine
from twisted.internet import defer
+from collections import namedtuple
import logging
@@ -29,6 +30,16 @@ logger = logging.getLogger(__name__)
MAX_STATE_DELTA_HOPS = 100
+class _GetStateGroupDelta(namedtuple("_GetStateGroupDelta", ("prev_group", "delta_ids"))):
+ """Return type of get_state_group_delta that implements __len__, which lets
+ us use the itrable flag when caching
+ """
+ __slots__ = []
+
+ def __len__(self):
+ return len(self.delta_ids) if self.delta_ids else 0
+
+
class StateStore(SQLBaseStore):
""" Keeps track of the state at a given event.
@@ -98,6 +109,46 @@ class StateStore(SQLBaseStore):
_get_current_state_ids_txn,
)
+ @cached(max_entries=10000, iterable=True)
+ def get_state_group_delta(self, state_group):
+ """Given a state group try to return a previous group and a delta between
+ the old and the new.
+
+ Returns:
+ (prev_group, delta_ids), where both may be None.
+ """
+ def _get_state_group_delta_txn(txn):
+ prev_group = self._simple_select_one_onecol_txn(
+ txn,
+ table="state_group_edges",
+ keyvalues={
+ "state_group": state_group,
+ },
+ retcol="prev_state_group",
+ allow_none=True,
+ )
+
+ if not prev_group:
+ return _GetStateGroupDelta(None, None)
+
+ delta_ids = self._simple_select_list_txn(
+ txn,
+ table="state_groups_state",
+ keyvalues={
+ "state_group": state_group,
+ },
+ retcols=("type", "state_key", "event_id",)
+ )
+
+ return _GetStateGroupDelta(prev_group, {
+ (row["type"], row["state_key"]): row["event_id"]
+ for row in delta_ids
+ })
+ return self.runInteraction(
+ "get_state_group_delta",
+ _get_state_group_delta_txn,
+ )
+
@defer.inlineCallbacks
def get_state_groups_ids(self, room_id, event_ids):
if not event_ids:
@@ -184,6 +235,19 @@ class StateStore(SQLBaseStore):
# We persist as a delta if we can, while also ensuring the chain
# of deltas isn't tooo long, as otherwise read performance degrades.
if context.prev_group:
+ is_in_db = self._simple_select_one_onecol_txn(
+ txn,
+ table="state_groups",
+ keyvalues={"id": context.prev_group},
+ retcol="id",
+ allow_none=True,
+ )
+ if not is_in_db:
+ raise Exception(
+ "Trying to persist state with unpersisted prev_group: %r"
+ % (context.prev_group,)
+ )
+
potential_hops = self._count_state_group_hops_txn(
txn, context.prev_group
)
@@ -251,6 +315,12 @@ class StateStore(SQLBaseStore):
],
)
+ for event_id, state_group_id in state_groups.iteritems():
+ txn.call_after(
+ self._get_state_group_for_event.prefill,
+ (event_id,), state_group_id
+ )
+
def _count_state_group_hops_txn(self, txn, state_group):
"""Given a state group, count how many hops there are in the tree.
@@ -520,8 +590,8 @@ class StateStore(SQLBaseStore):
state_map = yield self.get_state_ids_for_events([event_id], types)
defer.returnValue(state_map[event_id])
- @cached(num_args=2, max_entries=50000)
- def _get_state_group_for_event(self, room_id, event_id):
+ @cached(max_entries=50000)
+ def _get_state_group_for_event(self, event_id):
return self._simple_select_one_onecol(
table="event_to_state_groups",
keyvalues={
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