Fix a bug where solar conditions and status data were not properly persisted to disk between restarts. Release v2.0.5

core/single_object_data_cache.py

@@ -0,0 +1,39 @@
+import logging
+import threading
+
+import diskcache
+
+logger = logging.getLogger(__name__)
+
+
+class SingleObjectDataCache:
+    """Cache for status and solar conditions. This uses DiskCache, but unlike the standard DiskCache users like SIG and
+    callsign lookup handlers, status and solar conditions are persisted as a single object. If we just load the object
+    from DiskCache and modify it, DiskCache doesn't know that it's been updated and needs re-caching, so we provide a
+    store() method that any functions updating the object can call afterwards."""
+
+    def __init__(self, cache_dir, object_if_empty):
+        """Initialize a SingleObjectDataCache. Provide the directory to load the cache from and save it to. If the cache
+        is empty, the provided object_if_empty parameter will be used to initialise it."""
+
+        self._lock = threading.Lock()
+        self._cache = diskcache.Cache(cache_dir)
+        # This cache stores a single object, doesn't matter what it's called so "object" will do
+        if "object" not in self._cache:
+            self._cache.add("object", object_if_empty)
+        self._obj = self._cache.get("object")
+
+    def get(self):
+        """Get the data object. This can then be manipulated as necessary across multiple threads. Any function
+        modifying the object must remember to call store() afterwards."""
+        return self._obj
+
+    def store(self):
+        """Store the updated object in the cache. Any function modifying the object must remember to call this
+        afterwards."""
+        with self._lock:
+            self._cache.set("object", self._obj)
+
+    def close(self):
+        self.store()
+        self._cache.close()