Add LossRecorder and use moving average in all places

library/train_util.py

@@ -4685,3 +4685,20 @@ class collator_class:
         dataset.set_current_epoch(self.current_epoch.value)
         dataset.set_current_step(self.current_step.value)
         return examples[0]
+
+
+class LossRecorder:
+    def __init__(self):
+        self.loss_list: List[float] = []
+        self.loss_total: float = 0.0
+
+    def add(self, *, epoch:int, step: int, loss: float) -> None:
+        if epoch == 0:
+            self.loss_list.append(loss)
+        else:
+            self.loss_total -= self.loss_list[step]
+            self.loss_list[step] = loss
+        self.loss_total += loss
+
+    def get_moving_average(self) -> float:
+        return self.loss_total / len(self.loss_list)