Correctly start and stop subscriptions autochecker when it is

disabled/enabled in settings.

settings.py

@@ -286,6 +286,14 @@ if route_tor:
 else:
     print("Tor routing is OFF - your Youtube activity is NOT anonymous")
 
+hooks = {}
+def add_setting_changed_hook(setting, func):
+    '''Called right before new settings take effect'''
+    if setting in hooks:
+        hooks[setting].append(func)
+    else:
+        hooks[setting] = [func]
+
 
 def settings_page():
     if request.method == 'GET':
@@ -309,6 +317,13 @@ def settings_page():
             assert settings_info[setting_name]['type'] is bool, missing_inputs
             settings[setting_name] = False
 
+        # call setting hooks
+        for setting_name, value in settings.items():
+            old_value = globals()[setting_name]
+            if value != old_value and setting_name in hooks:
+                for func in hooks[setting_name]:
+                    func(old_value, value)
+
         globals().update(settings)
         save_settings(settings)
         return flask.redirect(util.URL_ORIGIN + '/settings', 303)

youtube/subscriptions.py

@@ -331,32 +331,6 @@ for i in range(0,5):
 
 
 # --- Auto checking system - Spaghetti code ---
-
-if settings.autocheck_subscriptions:
-    # job application format: dict with keys (channel_id, channel_name, next_check_time)
-    autocheck_job_application = gevent.queue.Queue() # only really meant to hold 1 item, just reusing gevent's wait and timeout machinery
-
-    autocheck_jobs = [] # list of dicts with the keys (channel_id, channel_name, next_check_time). Stores all the channels that need to be autochecked and when to check them
-    with open_database() as connection:
-        with connection as cursor:
-            now = time.time()
-            for row in cursor.execute('''SELECT yt_channel_id, channel_name, next_check_time FROM subscribed_channels WHERE muted != 1''').fetchall():
-
-                if row[2] is None:
-                    next_check_time = 0
-                else:
-                    next_check_time = row[2]
-
-                # expired, check randomly within the next hour
-                # note: even if it isn't scheduled in the past right now, it might end up being if it's due soon and we dont start dispatching by then, see below where time_until_earliest_job is negative
-                if next_check_time < now:
-                    next_check_time = now + 3600*secrets.randbelow(60)/60
-                    row = (row[0], row[1], next_check_time)
-                    _schedule_checking(cursor, row[0], next_check_time)
-                autocheck_jobs.append({'channel_id': row[0], 'channel_name': row[1], 'next_check_time': next_check_time})
-
-
-
 def autocheck_dispatcher():
     '''Scans the auto_check_list. Sleeps until the earliest job is due, then adds that channel to the checking queue above. Can be sent a new job through autocheck_job_application'''
     while True:
@@ -395,8 +369,49 @@ if settings.autocheck_subscriptions:
             check_channels_queue.put(earliest_job['channel_id'])
             del autocheck_jobs[earliest_job_index]
 
+dispatcher_greenlet = None
+def start_autocheck_system():
+    global autocheck_job_application
+    global autocheck_jobs
+    global dispatcher_greenlet
 
-    gevent.spawn(autocheck_dispatcher)
+    # job application format: dict with keys (channel_id, channel_name, next_check_time)
+    autocheck_job_application = gevent.queue.Queue() # only really meant to hold 1 item, just reusing gevent's wait and timeout machinery
+
+    autocheck_jobs = [] # list of dicts with the keys (channel_id, channel_name, next_check_time). Stores all the channels that need to be autochecked and when to check them
+    with open_database() as connection:
+        with connection as cursor:
+            now = time.time()
+            for row in cursor.execute('''SELECT yt_channel_id, channel_name, next_check_time FROM subscribed_channels WHERE muted != 1''').fetchall():
+
+                if row[2] is None:
+                    next_check_time = 0
+                else:
+                    next_check_time = row[2]
+
+                # expired, check randomly within the next hour
+                # note: even if it isn't scheduled in the past right now, it might end up being if it's due soon and we dont start dispatching by then, see below where time_until_earliest_job is negative
+                if next_check_time < now:
+                    next_check_time = now + 3600*secrets.randbelow(60)/60
+                    row = (row[0], row[1], next_check_time)
+                    _schedule_checking(cursor, row[0], next_check_time)
+                autocheck_jobs.append({'channel_id': row[0], 'channel_name': row[1], 'next_check_time': next_check_time})
+    dispatcher_greenlet = gevent.spawn(autocheck_dispatcher)
+
+def stop_autocheck_system():
+    if dispatcher_greenlet is not None:
+        dispatcher_greenlet.kill()
+
+def autocheck_setting_changed(old_value, new_value):
+    if new_value:
+        start_autocheck_system()
+    else:
+        stop_autocheck_system()
+
+settings.add_setting_changed_hook('autocheck_subscriptions',
+    autocheck_setting_changed)
+if settings.autocheck_subscriptions:
+    start_autocheck_system()
 # ----------------------------