Add PeriodicCache

freqtrade/configuration/PeriodicCache.py

@@ -0,0 +1,19 @@
+from datetime import datetime, timezone
+
+from cachetools.ttl import TTLCache
+
+
+class PeriodicCache(TTLCache):
+    """
+    Special cache that expires at "straight" times
+    A timer with ttl of 3600 (1h) will expire at every full hour (:00).
+    """
+
+    def __init__(self, maxsize, ttl, getsizeof=None):
+        def local_timer():
+            ts = datetime.now(timezone.utc).timestamp()
+            offset = (ts % ttl)
+            return ts - offset
+
+        # Init with smlight offset
+        super().__init__(maxsize=maxsize, ttl=ttl-1e-5, timer=local_timer, getsizeof=getsizeof)

freqtrade/configuration/__init__.py

@@ -1,5 +1,6 @@
 # flake8: noqa: F401
 
+from freqtrade.configuration.PeriodicCache import PeriodicCache
 from freqtrade.configuration.check_exchange import check_exchange, remove_credentials
 from freqtrade.configuration.config_setup import setup_utils_configuration
 from freqtrade.configuration.config_validation import validate_config_consistency

requirements-dev.txt

@@ -14,6 +14,8 @@ pytest-cov==2.12.1
 pytest-mock==3.6.1
 pytest-random-order==1.0.4
 isort==5.9.3
+# For datetime mocking
+time-machine==2.4.0
 
 # Convert jupyter notebooks to markdown documents
 nbconvert==6.1.0

tests/test_periodiccache.py

@@ -0,0 +1,31 @@
+from freqtrade.configuration import PeriodicCache
+import time_machine
+
+
+def test_ttl_cache():
+
+    with time_machine.travel("2021-09-01 05:00:00 +00:00") as t:
+
+        cache = PeriodicCache(5, ttl=60)
+        cache1h = PeriodicCache(5, ttl=3600)
+
+        assert cache.timer() == 1630472400.0
+        cache['a'] = 1235
+        cache1h['a'] = 555123
+        assert 'a' in cache
+        assert 'a' in cache1h
+
+        t.move_to("2021-09-01 05:00:59 +00:00")
+        assert 'a' in cache
+        assert 'a' in cache1h
+
+        # Cache expired
+        t.move_to("2021-09-01 05:01:00 +00:00")
+        assert 'a' not in cache
+        assert 'a' in cache1h
+
+        t.move_to("2021-09-01 05:59:59 +00:00")
+        assert 'a' in cache1h
+
+        t.move_to("2021-09-01 06:00:00 +00:00")
+        assert 'a' not in cache1h