perf: eliminate count queries in llm retry

bigframes/ml/base.py

@@ -22,7 +22,7 @@
 """
 
 import abc
-from typing import Callable, cast, Mapping, Optional, TypeVar
+from typing import Callable, cast, Mapping, Optional, TypeVar, Union
 import warnings
 
 import bigframes_vendored.sklearn.base
@@ -259,38 +259,29 @@ def _predict_and_retry(
     ) -> bpd.DataFrame:
         assert self._bqml_model is not None
 
-        df_result = bpd.DataFrame(session=self._bqml_model.session)  # placeholder
-        df_fail = X
-        for _ in range(max_retries + 1):
+        df_result: Union[bpd.DataFrame, None] = None  # placeholder
+        df_succ = df_fail = X
+        for i in range(max_retries + 1):
+            if i > 0 and df_fail.empty:
+                break
+            if i > 0 and df_succ.empty:
+                msg = bfe.format_message("Can't make any progress, stop retrying.")
+                warnings.warn(msg, category=RuntimeWarning)
+                break
+
             df = self._predict_func(df_fail, options)
 
             success = df[self._status_col].str.len() == 0
             df_succ = df[success]
             df_fail = df[~success]
 
-            if df_succ.empty:
-                if max_retries > 0:
-                    msg = bfe.format_message("Can't make any progress, stop retrying.")
-                    warnings.warn(msg, category=RuntimeWarning)
-                break
-
             df_result = (
-                bpd.concat([df_result, df_succ]) if not df_result.empty else df_succ
-            )
-
-            if df_fail.empty:
-                break
-
-        if not df_fail.empty:
-            msg = bfe.format_message(
-                f"Some predictions failed. Check column {self._status_col} for detailed "
-                "status. You may want to filter the failed rows and retry."
+                bpd.concat([df_result, df_succ]) if df_result is not None else df_succ
             )
-            warnings.warn(msg, category=RuntimeWarning)
 
         df_result = cast(
             bpd.DataFrame,
-            bpd.concat([df_result, df_fail]) if not df_result.empty else df_fail,
+            bpd.concat([df_result, df_fail]) if df_result is not None else df_fail,
         )
         return df_result