Avoid appending to external data when running onnx_save (#320)

* initial commit

* fix docstrings

* fix blunders in logic

---------

Co-authored-by: Michael Goin <michael@neuralmagic.com>

Author: dbogunowicz

src/sparsezoo/utils/onnx.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import logging
+import os
 from typing import Any, Dict, Optional, Tuple, Union
 
 import numpy
@@ -48,8 +49,11 @@
     "group_four_block",
     "extract_node_id",
     "get_node_attributes",
+    "EXTERNAL_ONNX_DATA_NAME",
 ]
 
+EXTERNAL_ONNX_DATA_NAME = "model.data"
+
 
 def onnx_includes_external_data(model: ModelProto) -> bool:
     """
@@ -75,7 +79,10 @@ def onnx_includes_external_data(model: ModelProto) -> bool:
 
 
 def save_onnx(
-    model: ModelProto, model_path: str, external_data_file: Optional[str] = None
+    model: ModelProto,
+    model_path: str,
+    large_model_external_data_file: str = EXTERNAL_ONNX_DATA_NAME,
+    external_data_file: Optional[str] = None,
 ) -> bool:
     """
     Save model to the given path.
@@ -88,11 +95,21 @@ def save_onnx(
 
     :param model: The model to save.
     :param model_path: The path to save the model to.
+    :param large_model_external_data_file: The default name to save the external
+        data to if the model is too large to be saved as a single protobuf.
+        If:
+         -  the model is too large to be saved as a single protobuf, AND
+         -  `external_data_file` is specified,
+        then the external data of the model will be saved to `external_data_file`
+        instead of `large_model_external_data_name`.
     :param external_data_file: The optional name save the external data to.
     :return True if the model was saved with external data, False otherwise.
     """
     if external_data_file is not None:
         _LOGGER.debug(f"Saving with external data: {external_data_file}")
+        _check_for_old_external_data(
+            model_path=model_path, external_data_file=external_data_file
+        )
         onnx.save(
             model,
             model_path,
@@ -104,16 +121,18 @@ def save_onnx(
 
     if model.ByteSize() > onnx.checker.MAXIMUM_PROTOBUF:
         _LOGGER.warning(
-            "The ONNX model is too large to be saved as a single protobuf."
-            "Saving with external data: 'model.data'"
+            "The ONNX model is too large to be saved as a single protobuf. "
+            f"Saving with external data: {large_model_external_data_file}"
+        )
+        _check_for_old_external_data(
+            model_path=model_path, external_data_file=large_model_external_data_file
         )
-
         onnx.save(
             model,
             model_path,
             save_as_external_data=True,
             all_tensors_to_one_file=True,
-            location="model.data",
+            location=large_model_external_data_file,
         )
         return True
 
@@ -566,3 +585,19 @@ def _get_node_input(
         return node.input[index]
     else:
         return default
+
+
+def _check_for_old_external_data(model_path: str, external_data_file: str):
+    old_external_data_file = os.path.join(
+        os.path.dirname(model_path), external_data_file
+    )
+    if os.path.exists(old_external_data_file):
+        _LOGGER.warning(
+            f"Attempting to save external data for a model: {model_path} "
+            f"to a directory:{os.path.dirname(model_path)} "
+            f"that already contains external data file: {external_data_file}. "
+            "The external data file will be overwritten."
+        )
+        os.remove(old_external_data_file)
+
+    return