fix(utils): fix epoch variable name in checkpoint save/load functions

src/so_vits_svc_fork/utils.py

@@ -238,7 +238,11 @@ def load_checkpoint(
                 "ignore", category=UserWarning, message="TypedStorage is deprecated"
             )
             checkpoint_dict = torch.load(f, map_location="cpu", weights_only=True)
-    iteration = checkpoint_dict["iteration"]
+    # The variable in this data structure was originally named 'iteration'.
+    # It has been renamed to 'epoch' to represent it's actual value.
+    # However, when loading this data structure from file, we still use 'iteration' to ensure
+    # backward compatibility with older checkpoint files
+    epoch = checkpoint_dict["iteration"]
     learning_rate = checkpoint_dict["learning_rate"]
 
     # safe load module
@@ -256,20 +260,20 @@ def load_checkpoint(
             warnings.simplefilter("ignore")
             safe_load(optimizer, checkpoint_dict["optimizer"])
 
-    LOG.info(f"Loaded checkpoint '{checkpoint_path}' (iteration {iteration})")
-    return model, optimizer, learning_rate, iteration
+    LOG.info(f"Loaded checkpoint '{checkpoint_path}' (epoch {epoch})")
+    return model, optimizer, learning_rate, epoch
 
 
 def save_checkpoint(
     model: torch.nn.Module,
     optimizer: torch.optim.Optimizer,
     learning_rate: float,
-    iteration: int,
+    epoch: int,
     checkpoint_path: Path | str,
 ) -> None:
     LOG.info(
-        "Saving model and optimizer state at iteration {} to {}".format(
-            iteration, checkpoint_path
+        "Saving model and optimizer state at epoch {} to {}".format(
+            epoch, checkpoint_path
         )
     )
     if hasattr(model, "module"):
@@ -280,7 +284,11 @@ def save_checkpoint(
         torch.save(
             {
                 "model": state_dict,
-                "iteration": iteration,
+                # The variable in this data structure was originally named 'iteration'.
+                # It has been renamed to 'epoch' to represent it's actual value.
+                # However, when saving this data structure to file, we still use 'iteration' to ensure
+                # backward compatibility with older checkpoint files
+                "iteration": epoch,
                 "optimizer": optimizer.state_dict(),
                 "learning_rate": learning_rate,
             },