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

@@ -331,8 +331,50 @@ for i in range(0,5):
 
 
 # --- Auto checking system - Spaghetti code ---
+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:
+        if len(autocheck_jobs) == 0:
+            new_job = autocheck_job_application.get()
+            autocheck_jobs.append(new_job)
+        else:
+            earliest_job_index = min(range(0, len(autocheck_jobs)), key=lambda index: autocheck_jobs[index]['next_check_time']) # https://stackoverflow.com/a/11825864
+            earliest_job = autocheck_jobs[earliest_job_index]
+            time_until_earliest_job = earliest_job['next_check_time'] - time.time()
+
+            if time_until_earliest_job <= -5:   # should not happen unless we're running extremely slow
+                print('ERROR: autocheck_dispatcher got job scheduled in the past, skipping and rescheduling: ' + earliest_job['channel_id'] + ', ' + earliest_job['channel_name'] + ', ' + str(earliest_job['next_check_time']))
+                next_check_time = time.time() + 3600*secrets.randbelow(60)/60
+                with_open_db(_schedule_checking, earliest_job['channel_id'], next_check_time)
+                autocheck_jobs[earliest_job_index]['next_check_time'] = next_check_time
+                continue
+
+            # make sure it's not muted
+            if with_open_db(_is_muted, earliest_job['channel_id']):
+                del autocheck_jobs[earliest_job_index]
+                continue
+
+            if time_until_earliest_job > 0: # it can become less than zero (in the past) when it's set to go off while the dispatcher is doing something else at that moment
+                try:
+                    new_job = autocheck_job_application.get(timeout = time_until_earliest_job)  # sleep for time_until_earliest_job time, but allow to be interrupted by new jobs
+                except gevent.queue.Empty: # no new jobs
+                    pass
+                else: # new job, add it to the list
+                    autocheck_jobs.append(new_job)
+                    continue
+
+            # no new jobs, time to execute the earliest job
+            channel_names[earliest_job['channel_id']] = earliest_job['channel_name']
+            checking_channels.add(earliest_job['channel_id'])
+            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
 
-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
 
@@ -354,49 +396,22 @@ if settings.autocheck_subscriptions:
                     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()
 
-    def autocheck_dispatcher():
+settings.add_setting_changed_hook('autocheck_subscriptions',
-        '''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'''
+    autocheck_setting_changed)
-        while True:
+if settings.autocheck_subscriptions:
-            if len(autocheck_jobs) == 0:
+    start_autocheck_system()
-                new_job = autocheck_job_application.get()
-                autocheck_jobs.append(new_job)
-            else:
-                earliest_job_index = min(range(0, len(autocheck_jobs)), key=lambda index: autocheck_jobs[index]['next_check_time']) # https://stackoverflow.com/a/11825864
-                earliest_job = autocheck_jobs[earliest_job_index]
-                time_until_earliest_job = earliest_job['next_check_time'] - time.time()
-
-                if time_until_earliest_job <= -5:   # should not happen unless we're running extremely slow
-                    print('ERROR: autocheck_dispatcher got job scheduled in the past, skipping and rescheduling: ' + earliest_job['channel_id'] + ', ' + earliest_job['channel_name'] + ', ' + str(earliest_job['next_check_time']))
-                    next_check_time = time.time() + 3600*secrets.randbelow(60)/60
-                    with_open_db(_schedule_checking, earliest_job['channel_id'], next_check_time)
-                    autocheck_jobs[earliest_job_index]['next_check_time'] = next_check_time
-                    continue
-
-                # make sure it's not muted
-                if with_open_db(_is_muted, earliest_job['channel_id']):
-                    del autocheck_jobs[earliest_job_index]
-                    continue
-
-                if time_until_earliest_job > 0: # it can become less than zero (in the past) when it's set to go off while the dispatcher is doing something else at that moment
-                    try:
-                        new_job = autocheck_job_application.get(timeout = time_until_earliest_job)  # sleep for time_until_earliest_job time, but allow to be interrupted by new jobs
-                    except gevent.queue.Empty: # no new jobs
-                        pass
-                    else: # new job, add it to the list
-                        autocheck_jobs.append(new_job)
-                        continue
-
-                # no new jobs, time to execute the earliest job
-                channel_names[earliest_job['channel_id']] = earliest_job['channel_name']
-                checking_channels.add(earliest_job['channel_id'])
-                check_channels_queue.put(earliest_job['channel_id'])
-                del autocheck_jobs[earliest_job_index]
-
-
-    gevent.spawn(autocheck_dispatcher)
 # ----------------------------