[enh] add searx.shared

shared dictionary between the workers (UWSGI or werkzeug)
scheduler: run a task once every x seconds (UWSGI or werkzeug)

searx/shared/shared_simple.py

@@ -0,0 +1,38 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+import threading
+
+from . import shared_abstract
+
+
+class SimpleSharedDict(shared_abstract.SharedDict):
+
+    __slots__ = 'd',
+
+    def __init__(self):
+        self.d = {}
+
+    def get_int(self, key):
+        return self.d.get(key, None)
+
+    def set_int(self, key, value):
+        self.d[key] = value
+
+    def get_str(self, key):
+        return self.d.get(key, None)
+
+    def set_str(self, key, value):
+        self.d[key] = value
+
+
+def schedule(delay, func, *args):
+    def call_later():
+        t = threading.Timer(delay, wrapper)
+        t.daemon = True
+        t.start()
+
+    def wrapper():
+        call_later()
+        func(*args)
+
+    call_later()