improve multithreaded training queue system

freqtrade/freqai/data_drawer.py

@@ -18,7 +18,7 @@ class FreqaiDataDrawer:
     This object remains persistent throughout live/dry, unlike FreqaiDataKitchen, which is
     reinstantiated for each coin.
     """
-    def __init__(self, full_path: Path):
+    def __init__(self, full_path: Path, pair_whitelist):
 
         # dictionary holding all pair metadata necessary to load in from disk
         self.pair_dict: Dict[str, Any] = {}
@@ -27,6 +27,8 @@ class FreqaiDataDrawer:
         self.pair_data_dict: Dict[str, Any] = {}
         self.full_path = full_path
         self.load_drawer_from_disk()
+        self.training_queue: Dict[str, int] = {}
+        self.create_training_queue(pair_whitelist)
 
     def load_drawer_from_disk(self):
         exists = Path(self.full_path / str('pair_dictionary.json')).resolve().exists()
@@ -71,3 +73,15 @@ class FreqaiDataDrawer:
             self.pair_dict[metadata['pair']]['trained_timestamp'] = 0
             self.pair_dict[metadata['pair']]['priority'] = 1
             return
+
+    def create_training_queue(self, pairs: list) -> None:
+        for i, pair in enumerate(pairs):
+            self.training_queue[pair] = i + 1
+
+    def pair_to_end_of_training_queue(self, pair: str) -> None:
+        # march all pairs up in the queue
+        for p in self.training_queue:
+            self.training_queue[p] -= 1
+
+        # send pair to end of queue
+        self.training_queue[pair] = len(self.training_queue)