From 615e1183a81752e1b79601e973742e3214f4f51e Mon Sep 17 00:00:00 2001
From: Ian Renton <ian@ianrenton.com>
Date: Sun, 21 Jun 2026 22:07:29 +0100
Subject: [PATCH] Fix cache multithreading issues on startup?

---
 core/cache_utils.py       | 20 +++++++++++++++++---
 templates/add_spot.html   |  2 +-
 templates/alerts.html     |  2 +-
 templates/bands.html      |  4 ++--
 templates/base.html       | 10 +++++-----
 templates/conditions.html |  2 +-
 templates/map.html        |  4 ++--
 templates/spots.html      |  4 ++--
 templates/status.html     |  2 +-
 9 files changed, 32 insertions(+), 18 deletions(-)

diff --git a/core/cache_utils.py b/core/cache_utils.py
index 3093c2f..2ec492c 100644
--- a/core/cache_utils.py
+++ b/core/cache_utils.py
@@ -1,3 +1,4 @@
+import threading
 from datetime import timedelta
 
 from requests_cache import CachedSession
@@ -5,6 +6,19 @@ from requests_cache import CachedSession
 # Cache for "semi-static" data such as the locations of parks, CSVs of reference lists, etc.
 # This has an expiry time of 30 days, so will re-request from the source after that amount
 # of time has passed. This is used throughout Spothole to cache data that does not change
-# rapidly.
-SEMI_STATIC_URL_DATA_CACHE = CachedSession("cache/semi_static_url_data_cache",
-                                           expire_after=timedelta(days=30))
+# rapidly. The ThreadSafeSession construct here protects it against some multithreading
+# contention weirdness we sometimes used to see on startup where the cache was hammered
+# pretty hard.
+_session = CachedSession("cache/semi_static_url_data_cache", expire_after=timedelta(days=30))
+_lock = threading.Lock()
+
+
+class _ThreadSafeSession:
+    """Wraps CachedSession with a lock to prevent concurrent SQLite access across threads."""
+
+    def get(self, *args, **kwargs):
+        with _lock:
+            return _session.get(*args, **kwargs)
+
+
+SEMI_STATIC_URL_DATA_CACHE = _ThreadSafeSession()
diff --git a/templates/add_spot.html b/templates/add_spot.html
index 36992f7..380afec 100644
--- a/templates/add_spot.html
+++ b/templates/add_spot.html
@@ -76,7 +76,7 @@
 
 </div>
 
-<script src="/js/add-spot.js?v=1782075686"></script>
+<script src="/js/add-spot.js?v=1782076050"></script>
 <script>$(document).ready(function () {
     $("#nav-link-add-spot").addClass("active");
 }); <!-- highlight active page in nav --></script>
diff --git a/templates/alerts.html b/templates/alerts.html
index 9a240b9..fef1ee6 100644
--- a/templates/alerts.html
+++ b/templates/alerts.html
@@ -75,7 +75,7 @@
 
 </div>
 
-<script src="/js/alerts.js?v=1782075686"></script>
+<script src="/js/alerts.js?v=1782076050"></script>
 <script>$(document).ready(function () {
     $("#nav-link-alerts").addClass("active");
 }); <!-- highlight active page in nav --></script>
diff --git a/templates/bands.html b/templates/bands.html
index 21c6af2..50fce7a 100644
--- a/templates/bands.html
+++ b/templates/bands.html
@@ -77,8 +77,8 @@
 <script>
     let spotProvidersEnabledByDefault = {% raw json_encode(web_ui_options["spot-providers-enabled-by-default"]) %};
 </script>
-<script src="/js/spotsbandsandmap.js?v=1782075686"></script>
-<script src="/js/bands.js?v=1782075686"></script>
+<script src="/js/spotsbandsandmap.js?v=1782076050"></script>
+<script src="/js/bands.js?v=1782076050"></script>
 <script>$(document).ready(function () {
     $("#nav-link-bands").addClass("active");
 }); <!-- highlight active page in nav --></script>
diff --git a/templates/base.html b/templates/base.html
index b6cbc90..36341da 100644
--- a/templates/base.html
+++ b/templates/base.html
@@ -1,6 +1,6 @@
 {% extends "skeleton.html" %}
 {% block head_extra %}
-<link rel="stylesheet" href="/css/style.css?v=1782075686" type="text/css">
+<link rel="stylesheet" href="/css/style.css?v=1782076050" type="text/css">
 <link href="/vendor/css/bootstrap-5.3.8.min.css" rel="stylesheet">
 <link href="/vendor/css/fontawesome-6.7.2.min.css" rel="stylesheet">
 <link href="/vendor/css/solid-6.7.2.min.css" rel="stylesheet">
@@ -10,10 +10,10 @@
 <script src="/vendor/js/bootstrap-5.3.8.bundle.min.js"></script>
 <script src="/vendor/js/tinycolor2-1.6.0.min.js"></script>
 
-<script src="/js/utils.js?v=1782075686"></script>
-<script src="/js/ui-ham.js?v=1782075686"></script>
-<script src="/js/geo.js?v=1782075686"></script>
-<script src="/js/common.js?v=1782075686"></script>
+<script src="/js/utils.js?v=1782076050"></script>
+<script src="/js/ui-ham.js?v=1782076050"></script>
+<script src="/js/geo.js?v=1782076050"></script>
+<script src="/js/common.js?v=1782076050"></script>
 {% end %}
 {% block body %}
 <div class="container">
diff --git a/templates/conditions.html b/templates/conditions.html
index 8a07ffb..dbcdf49 100644
--- a/templates/conditions.html
+++ b/templates/conditions.html
@@ -284,7 +284,7 @@
 </div>
 
 <script src="/vendor/js/chart-4.4.9.umd.min.js"></script>
-<script src="/js/conditions.js?v=1782075686"></script>
+<script src="/js/conditions.js?v=1782076050"></script>
 <script>$(document).ready(function () {
     $("#nav-link-conditions").addClass("active");
 }); <!-- highlight active page in nav --></script>
diff --git a/templates/map.html b/templates/map.html
index c135728..ca953b5 100644
--- a/templates/map.html
+++ b/templates/map.html
@@ -95,8 +95,8 @@
 <script>
     let spotProvidersEnabledByDefault = {% raw json_encode(web_ui_options["spot-providers-enabled-by-default"]) %};
 </script>
-<script src="/js/spotsbandsandmap.js?v=1782075686"></script>
-<script src="/js/map.js?v=1782075686"></script>
+<script src="/js/spotsbandsandmap.js?v=1782076049"></script>
+<script src="/js/map.js?v=1782076049"></script>
 <script>$(document).ready(function () {
     $("#nav-link-map").addClass("active");
 }); <!-- highlight active page in nav --></script>
diff --git a/templates/spots.html b/templates/spots.html
index c921a6e..df3a546 100644
--- a/templates/spots.html
+++ b/templates/spots.html
@@ -116,8 +116,8 @@
 <script>
     let spotProvidersEnabledByDefault = {% raw json_encode(web_ui_options["spot-providers-enabled-by-default"]) %};
 </script>
-<script src="/js/spotsbandsandmap.js?v=1782075686"></script>
-<script src="/js/spots.js?v=1782075686"></script>
+<script src="/js/spotsbandsandmap.js?v=1782076049"></script>
+<script src="/js/spots.js?v=1782076049"></script>
 <script>$(document).ready(function () {
     $("#nav-link-spots").addClass("active");
 }); <!-- highlight active page in nav --></script>
diff --git a/templates/status.html b/templates/status.html
index 191d443..9472818 100644
--- a/templates/status.html
+++ b/templates/status.html
@@ -59,7 +59,7 @@
     </div>
 </div>
 
-<script src="/js/status.js?v=1782075686"></script>
+<script src="/js/status.js?v=1782076050"></script>
 <script>
     $(document).ready(function () {
         $("#nav-link-status").addClass("active");