make file name an arg

Signed-off-by: Peng Zhang <pengz@uber.com>

horovod/spark/common/store.py

@@ -168,14 +168,16 @@ class AbstractFilesystemStore(Store):
     """Abstract class for stores that use a filesystem for underlying storage."""
 
     def __init__(self, prefix_path, train_path=None, val_path=None, test_path=None,
-            runs_path=None, save_runs=True, storage_options=None, **kwargs):
+            runs_path=None, save_runs=True, storage_options=None, checkpoint_filename=None,
+            **kwargs):
         self.prefix_path = self.get_full_path(prefix_path)
         self._train_path = self._get_full_path_or_default(train_path, 'intermediate_train_data')
         self._val_path = self._get_full_path_or_default(val_path, 'intermediate_val_data')
         self._test_path = self._get_full_path_or_default(test_path, 'intermediate_test_data')
         self._runs_path = self._get_full_path_or_default(runs_path, 'runs')
         self._save_runs = save_runs
         self.storage_options = storage_options
+        self.checkpoint_filename = checkpoint_filename if checkpoint_filename else 'checkpoint'
         super().__init__()
 
     def exists(self, path):
@@ -262,8 +264,7 @@ def get_logs_path(self, run_id):
             if self._save_runs else None
 
     def get_checkpoint_filename(self):
-        # default the store checkpoint name to use h5 format
-        return 'checkpoint.h5'
+        return self.checkpoint_filename
 
     def get_logs_subdir(self):
         return 'logs'