From 03aff4c75ed3b0b106ed1395b3d03b1ab9b013a6 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Fri, 15 May 2020 17:22:47 +0100
Subject: [PATCH] Add a worker store for search insertion. (#7516)

This is required as both event persistence and the background update needs access to this function. It should be perfectly safe for two workers to write to that table at the same time.
---
 changelog.d/7516.misc                      |  1 +
 synapse/app/generic_worker.py              |  2 +
 synapse/storage/data_stores/main/search.py | 96 +++++++++++-----------
 3 files changed, 52 insertions(+), 47 deletions(-)
 create mode 100644 changelog.d/7516.misc

diff --git a/changelog.d/7516.misc b/changelog.d/7516.misc
new file mode 100644
index 0000000000..94b0fd49b2
--- /dev/null
+++ b/changelog.d/7516.misc
@@ -0,0 +1 @@
+Add a worker store for search insertion, required for moving event persistence off master.
diff --git a/synapse/app/generic_worker.py b/synapse/app/generic_worker.py
index 2e3add7ac5..ab801108ca 100644
--- a/synapse/app/generic_worker.py
+++ b/synapse/app/generic_worker.py
@@ -122,6 +122,7 @@ from synapse.storage.data_stores.main.monthly_active_users import (
     MonthlyActiveUsersWorkerStore,
 )
 from synapse.storage.data_stores.main.presence import UserPresenceState
+from synapse.storage.data_stores.main.search import SearchWorkerStore
 from synapse.storage.data_stores.main.ui_auth import UIAuthWorkerStore
 from synapse.storage.data_stores.main.user_directory import UserDirectoryStore
 from synapse.types import ReadReceipt
@@ -451,6 +452,7 @@ class GenericWorkerSlavedStore(
     SlavedFilteringStore,
     MonthlyActiveUsersWorkerStore,
     MediaRepositoryStore,
+    SearchWorkerStore,
     BaseSlavedStore,
 ):
     def __init__(self, database, db_conn, hs):
diff --git a/synapse/storage/data_stores/main/search.py b/synapse/storage/data_stores/main/search.py
index ee75b92344..13f49d8060 100644
--- a/synapse/storage/data_stores/main/search.py
+++ b/synapse/storage/data_stores/main/search.py
@@ -37,7 +37,55 @@ SearchEntry = namedtuple(
 )
 
 
-class SearchBackgroundUpdateStore(SQLBaseStore):
+class SearchWorkerStore(SQLBaseStore):
+    def store_search_entries_txn(self, txn, entries):
+        """Add entries to the search table
+
+        Args:
+            txn (cursor):
+            entries (iterable[SearchEntry]):
+                entries to be added to the table
+        """
+        if not self.hs.config.enable_search:
+            return
+        if isinstance(self.database_engine, PostgresEngine):
+            sql = (
+                "INSERT INTO event_search"
+                " (event_id, room_id, key, vector, stream_ordering, origin_server_ts)"
+                " VALUES (?,?,?,to_tsvector('english', ?),?,?)"
+            )
+
+            args = (
+                (
+                    entry.event_id,
+                    entry.room_id,
+                    entry.key,
+                    entry.value,
+                    entry.stream_ordering,
+                    entry.origin_server_ts,
+                )
+                for entry in entries
+            )
+
+            txn.executemany(sql, args)
+
+        elif isinstance(self.database_engine, Sqlite3Engine):
+            sql = (
+                "INSERT INTO event_search (event_id, room_id, key, value)"
+                " VALUES (?,?,?,?)"
+            )
+            args = (
+                (entry.event_id, entry.room_id, entry.key, entry.value)
+                for entry in entries
+            )
+
+            txn.executemany(sql, args)
+        else:
+            # This should be unreachable.
+            raise Exception("Unrecognized database engine")
+
+
+class SearchBackgroundUpdateStore(SearchWorkerStore):
 
     EVENT_SEARCH_UPDATE_NAME = "event_search"
     EVENT_SEARCH_ORDER_UPDATE_NAME = "event_search_order"
@@ -296,52 +344,6 @@ class SearchBackgroundUpdateStore(SQLBaseStore):
 
         return num_rows
 
-    def store_search_entries_txn(self, txn, entries):
-        """Add entries to the search table
-
-        Args:
-            txn (cursor):
-            entries (iterable[SearchEntry]):
-                entries to be added to the table
-        """
-        if not self.hs.config.enable_search:
-            return
-        if isinstance(self.database_engine, PostgresEngine):
-            sql = (
-                "INSERT INTO event_search"
-                " (event_id, room_id, key, vector, stream_ordering, origin_server_ts)"
-                " VALUES (?,?,?,to_tsvector('english', ?),?,?)"
-            )
-
-            args = (
-                (
-                    entry.event_id,
-                    entry.room_id,
-                    entry.key,
-                    entry.value,
-                    entry.stream_ordering,
-                    entry.origin_server_ts,
-                )
-                for entry in entries
-            )
-
-            txn.executemany(sql, args)
-
-        elif isinstance(self.database_engine, Sqlite3Engine):
-            sql = (
-                "INSERT INTO event_search (event_id, room_id, key, value)"
-                " VALUES (?,?,?,?)"
-            )
-            args = (
-                (entry.event_id, entry.room_id, entry.key, entry.value)
-                for entry in entries
-            )
-
-            txn.executemany(sql, args)
-        else:
-            # This should be unreachable.
-            raise Exception("Unrecognized database engine")
-
 
 class SearchStore(SearchBackgroundUpdateStore):
     def __init__(self, database: Database, db_conn, hs):