2 files changed, 89 insertions, 1 deletions
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index ae1ad56d9a..d32ce1ab1e 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -160,7 +160,7 @@ class RoomMemberStore(SQLBaseStore):
 
     def _get_rooms_for_user_where_membership_is_txn(self, txn, user_id,
                                                     membership_list):
-        where_clause = "user_id = ? AND (%s)" % (
+        where_clause = "user_id = ? AND (%s) AND NOT forgotten" % (
             " OR ".join(["membership = ?" for _ in membership_list]),
         )
 
@@ -269,3 +269,67 @@ class RoomMemberStore(SQLBaseStore):
         ret = len(room_id_lists.pop(0).intersection(*room_id_lists)) > 0
 
         defer.returnValue(ret)
+
+    def forget(self, user_id, room_id):
+        """Indicate that user_id wishes to discard history for room_id."""
+        def f(txn):
+            sql = (
+                "UPDATE"
+                "  room_memberships"
+                " SET"
+                "  forgotten = 1"
+                " WHERE"
+                "  user_id = ?"
+                " AND"
+                "  room_id = ?"
+            )
+            txn.execute(sql, (user_id, room_id))
+        self.runInteraction("forget_membership", f)
+
+    @defer.inlineCallbacks
+    def did_forget(self, user_id, room_id):
+        """Returns whether user_id has elected to discard history for room_id.
+
+        Returns False if they have since re-joined."""
+        def f(txn):
+            sql = (
+                "SELECT"
+                "  COUNT(*)"
+                " FROM"
+                "  room_memberships"
+                " WHERE"
+                "  user_id = ?"
+                " AND"
+                "  room_id = ?"
+                " AND"
+                "  forgotten = 0"
+            )
+            txn.execute(sql, (user_id, room_id))
+            rows = txn.fetchall()
+            return rows[0][0]
+        count = yield self.runInteraction("did_forget_membership", f)
+        defer.returnValue(count == 0)
+
+    @defer.inlineCallbacks
+    def was_forgotten_at(self, user_id, room_id, event_id):
+        """Returns whether user_id has elected to discard history for room_id at event_id.
+
+        event_id must be a membership event."""
+        def f(txn):
+            sql = (
+                "SELECT"
+                "  forgotten"
+                " FROM"
+                "  room_memberships"
+                " WHERE"
+                "  user_id = ?"
+                " AND"
+                "  room_id = ?"
+                " AND"
+                "  event_id = ?"
+            )
+            txn.execute(sql, (user_id, room_id, event_id))
+            rows = txn.fetchall()
+            return rows[0][0]
+        forgot = yield self.runInteraction("did_forget_membership_at", f)
+        defer.returnValue(forgot == 1)
diff --git a/synapse/storage/schema/delta/26/forgotten_memberships.sql b/synapse/storage/schema/delta/26/forgotten_memberships.sql
new file mode 100644
index 0000000000..df55b9c6f6
--- /dev/null
+++ b/synapse/storage/schema/delta/26/forgotten_memberships.sql
@@ -0,0 +1,24 @@
+/* Copyright 2015 OpenMarket Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Keeps track of what rooms users have left and don't want to be able to
+ * access again.
+ *
+ * If all users on this server have left a room, we can delete the room
+ * entirely.
+ */
+
+ ALTER TABLE room_memberships ADD COLUMN forgotten INTEGER(1) DEFAULT 0;