espnet3.utils.logging_utils.set_stage_log_handler

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espnet3.utils.logging_utils.set_stage_log_handler(log_dir: Path | None, filename: str) → Path | None

Attach a file handler for a stage log, replacing any prior stage handler.

This function adds a new file handler to the root logger and removes any previously installed stage handler (identified via _espnet3_stage_log). If a log file already exists at the target path, it is rotated (e.g., train.log -> train1.log) before creating the new handler.

• Parameters:
  • logger (logging.Logger) – Logger used to emit logs. The handler is attached to the root logger so the logger hierarchy continues to work as expected.
  • log_dir (Path | None) – Directory that should receive the stage log. If None, no handler is installed and None is returned.
  • filename (str) – Log filename to create within log_dir.
• Returns: Resolved log file path when installed, otherwise None.
• Return type: Path | None