From 57ff573535bca54bce3cae6f3c1a7c6bc2bac13a Mon Sep 17 00:00:00 2001
From: Alex Vandiver <alexmv@zulip.com>
Date: Mon, 15 Apr 2024 19:40:37 +0000
Subject: [PATCH] topic: Move sqlalchemy methods into their own file.

Loading sqlalchemy can take a significant amount of time, so splitting
these into these own file can be a significant startup-time savings.
---
 tools/linter_lib/custom_check.py |  1 +
 zerver/lib/narrow.py             |  5 ++---
 zerver/lib/topic.py              | 18 ------------------
 zerver/lib/topic_sqlalchemy.py   | 20 ++++++++++++++++++++
 zerver/lib/user_topics.py        |  2 +-
 zerver/views/message_fetch.py    |  3 ++-
 6 files changed, 26 insertions(+), 23 deletions(-)
 create mode 100644 zerver/lib/topic_sqlalchemy.py

diff --git a/tools/linter_lib/custom_check.py b/tools/linter_lib/custom_check.py
index 2d95b545a5..1a08da952e 100644
--- a/tools/linter_lib/custom_check.py
+++ b/tools/linter_lib/custom_check.py
@@ -13,6 +13,7 @@ from zulint.custom_rules import Rule, RuleList
 FILES_WITH_LEGACY_SUBJECT = {
     # This basically requires a big DB migration:
     "zerver/lib/topic.py",
+    "zerver/lib/topic_sqlalchemy.py",
     # This is for backward compatibility.
     "zerver/tests/test_legacy_subject.py",
     # Other migration-related changes require extreme care.
diff --git a/zerver/lib/narrow.py b/zerver/lib/narrow.py
index 3116c521ae..4970cfc4ec 100644
--- a/zerver/lib/narrow.py
+++ b/zerver/lib/narrow.py
@@ -58,10 +58,9 @@ from zerver.lib.streams import (
     get_stream_by_narrow_operand_access_unchecked,
     get_web_public_streams_queryset,
 )
-from zerver.lib.topic import (
-    RESOLVED_TOPIC_PREFIX,
+from zerver.lib.topic import RESOLVED_TOPIC_PREFIX, get_topic_from_message_info
+from zerver.lib.topic_sqlalchemy import (
     get_resolved_topic_condition_sa,
-    get_topic_from_message_info,
     topic_column_sa,
     topic_match_sa,
 )
diff --git a/zerver/lib/topic.py b/zerver/lib/topic.py
index 577d2db3fe..281b3db431 100644
--- a/zerver/lib/topic.py
+++ b/zerver/lib/topic.py
@@ -5,8 +5,6 @@ import orjson
 from django.db import connection
 from django.db.models import F, Func, JSONField, Q, QuerySet, Subquery, TextField, Value
 from django.db.models.functions import Cast
-from sqlalchemy.sql import ColumnElement, column, func, literal
-from sqlalchemy.types import Boolean, Text
 
 from zerver.lib.request import REQ
 from zerver.lib.types import EditHistoryEvent
@@ -72,22 +70,6 @@ DB_TOPIC_NAME = "subject"
 MESSAGE__TOPIC = "message__subject"
 
 
-def topic_match_sa(topic_name: str) -> ColumnElement[Boolean]:
-    # _sa is short for SQLAlchemy, which we use mostly for
-    # queries that search messages
-    topic_cond = func.upper(column("subject", Text)) == func.upper(literal(topic_name))
-    return topic_cond
-
-
-def get_resolved_topic_condition_sa() -> ColumnElement[Boolean]:
-    resolved_topic_cond = column("subject", Text).startswith(RESOLVED_TOPIC_PREFIX)
-    return resolved_topic_cond
-
-
-def topic_column_sa() -> ColumnElement[Text]:
-    return column("subject", Text)
-
-
 def filter_by_topic_name_via_message(
     query: QuerySet[UserMessage], topic_name: str
 ) -> QuerySet[UserMessage]:
diff --git a/zerver/lib/topic_sqlalchemy.py b/zerver/lib/topic_sqlalchemy.py
new file mode 100644
index 0000000000..6bbab54b89
--- /dev/null
+++ b/zerver/lib/topic_sqlalchemy.py
@@ -0,0 +1,20 @@
+from sqlalchemy.sql import ColumnElement, column, func, literal
+from sqlalchemy.types import Boolean, Text
+
+from zerver.lib.topic import RESOLVED_TOPIC_PREFIX
+
+
+def topic_match_sa(topic_name: str) -> ColumnElement[Boolean]:
+    # _sa is short for SQLAlchemy, which we use mostly for
+    # queries that search messages
+    topic_cond = func.upper(column("subject", Text)) == func.upper(literal(topic_name))
+    return topic_cond
+
+
+def get_resolved_topic_condition_sa() -> ColumnElement[Boolean]:
+    resolved_topic_cond = column("subject", Text).startswith(RESOLVED_TOPIC_PREFIX)
+    return resolved_topic_cond
+
+
+def topic_column_sa() -> ColumnElement[Text]:
+    return column("subject", Text)
diff --git a/zerver/lib/user_topics.py b/zerver/lib/user_topics.py
index 6daa693310..01dfe432c4 100644
--- a/zerver/lib/user_topics.py
+++ b/zerver/lib/user_topics.py
@@ -10,7 +10,7 @@ from sqlalchemy.sql import ClauseElement, and_, column, not_, or_
 from sqlalchemy.types import Integer
 
 from zerver.lib.timestamp import datetime_to_timestamp
-from zerver.lib.topic import topic_match_sa
+from zerver.lib.topic_sqlalchemy import topic_match_sa
 from zerver.lib.types import UserTopicDict
 from zerver.models import UserProfile, UserTopic
 from zerver.models.streams import get_stream
diff --git a/zerver/views/message_fetch.py b/zerver/views/message_fetch.py
index 82a96275fb..c2b9b67711 100644
--- a/zerver/views/message_fetch.py
+++ b/zerver/views/message_fetch.py
@@ -24,7 +24,8 @@ from zerver.lib.narrow import (
 from zerver.lib.request import REQ, RequestNotes, has_request_variables
 from zerver.lib.response import json_success
 from zerver.lib.sqlalchemy_utils import get_sqlalchemy_connection
-from zerver.lib.topic import DB_TOPIC_NAME, MATCH_TOPIC, topic_column_sa
+from zerver.lib.topic import DB_TOPIC_NAME, MATCH_TOPIC
+from zerver.lib.topic_sqlalchemy import topic_column_sa
 from zerver.lib.validator import check_bool, check_int, check_list, to_non_negative_int
 from zerver.models import UserMessage, UserProfile