Refactor of caching & data storage part 9 #118

providers/spot/spot_provider.py

@@ -0,0 +1,60 @@
+from datetime import datetime
+
+import pytz
+
+from core.data_store import DATA_STORE
+
+
+class SpotProvider:
+    """Generic spot provider class. Subclasses of this query the individual APIs for data."""
+
+    def __init__(self, name, provider_config):
+        """Constructor"""
+
+        self.name = name
+        self.enabled = provider_config["enabled"]
+        self.last_update_time = datetime.min.replace(tzinfo=pytz.UTC)
+        self.last_spot_time = datetime.min.replace(tzinfo=pytz.UTC)
+        self.status = "Not Started" if self.enabled else "Disabled"
+        self._spots = DATA_STORE.spots
+
+    def start(self):
+        """Start the provider. This should return immediately after spawning threads to access the remote resources"""
+
+        raise NotImplementedError("Subclasses must implement this method")
+
+    def _submit_batch(self, spots):
+        """Submit a batch of spots retrieved from the provider. Only spots that are newer than the last spot retrieved
+        by this provider will be added to the spot list, to prevent duplications. Spots passing the check will also have
+        their infer_missing() method called to complete their data set. This is called by the API-querying
+        subclasses on receiving spots."""
+
+        # Sort the batch so that earliest ones go in first. This helps keep the ordering correct when spots are fired
+        # off to SSE listeners.
+        spots = sorted(spots, key=lambda s: (s.time if s and s.time else 0))
+        for spot in spots:
+            if datetime.fromtimestamp(spot.time, pytz.UTC) > self.last_spot_time:
+                # Fill in any blanks and add to the list
+                spot.infer_missing()
+                self._add_spot(spot)
+        if spots:
+            self.last_spot_time = datetime.fromtimestamp(max(map(lambda s: s.time, spots)), pytz.UTC)
+
+    def _submit(self, spot):
+        """Submit a single spot retrieved from the provider. This will be added to the list regardless of its age. Spots
+        passing the check will also have their infer_missing() method called to complete their data set. This is called by
+        the data streaming subclasses, which can be relied upon not to re-provide old spots."""
+
+        # Fill in any blanks and add to the list
+        spot.infer_missing()
+        self._add_spot(spot)
+        self.last_spot_time = datetime.fromtimestamp(spot.time, pytz.UTC)
+
+    def _add_spot(self, spot):
+        if not spot.expired():
+            self._spots.set(spot.id, spot)
+
+    def stop(self):
+        """Stop any threads and prepare for application shutdown"""
+
+        raise NotImplementedError("Subclasses must implement this method")