The checker requires Redis

Remove the abstraction in searx.shared.SharedDict.
Implement a basic and dedicated scheduler for the checker using a Redis script.

searx/shared/__init__.py

@@ -1,39 +1,6 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
+# lint: pylint
+"""Initialization of a *shared* storage.
+"""
 
-import logging
-import importlib
-
-logger = logging.getLogger('searx.shared')
-
-__all__ = ['SharedDict', 'schedule']
-
-try:
-    uwsgi = importlib.import_module('uwsgi')
-except:
-    # no uwsgi
-    from .shared_simple import SimpleSharedDict as SharedDict, schedule
-
-    logger.info('Use shared_simple implementation')
-else:
-    try:
-        uwsgi.cache_update('dummy', b'dummy')
-        if uwsgi.cache_get('dummy') != b'dummy':
-            raise Exception()
-    except:
-        # uwsgi.ini configuration problem: disable all scheduling
-        logger.error(
-            'uwsgi.ini configuration error, add this line to your uwsgi.ini\n'
-            'cache2 = name=searxngcache,items=2000,blocks=2000,blocksize=4096,bitmap=1'
-        )
-        from .shared_simple import SimpleSharedDict as SharedDict
-
-        def schedule(delay, func, *args):
-            return False
-
-    else:
-        # uwsgi
-        from .shared_uwsgi import UwsgiCacheSharedDict as SharedDict, schedule
-
-        logger.info('Use shared_uwsgi implementation')
-
-storage = SharedDict()
+from . import redisdb