Use a database table to hold the users that should have full presence sent to them, instead of something in-memory (#9823)

1 files changed, 34 insertions, 0 deletions

diff --git a/synapse/storage/schema/main/delta/59/13users_to_send_full_presence_to.sql b/synapse/storage/schema/main/delta/59/13users_to_send_full_presence_to.sql
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index 0000000000..07b0f53ecf
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+/* Copyright 2021 The Matrix.org Foundation C.I.C
+ *
+ * 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.
+ */
+
+-- Add a table that keeps track of a list of users who should, upon their next
+-- sync request, receive presence for all currently online users that they are
+-- "interested" in.
+
+-- The motivation for a DB table over an in-memory list is so that this list
+-- can be added to and retrieved from by any worker. Specifically, we don't
+-- want to duplicate work across multiple sync workers.
+
+CREATE TABLE IF NOT EXISTS users_to_send_full_presence_to(
+    -- The user ID to send full presence to.
+    user_id TEXT PRIMARY KEY,
+    -- A presence stream ID token - the current presence stream token when the row was last upserted.
+    -- If a user calls /sync and this token is part of the update they're to receive, we also include
+    -- full user presence in the response.
+    -- This allows multiple devices for a user to receive full presence whenever they next call /sync.
+    presence_stream_id BIGINT,
+    FOREIGN KEY (user_id)
+        REFERENCES users (name)
+);
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