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Lightning callback

ResearchTrackerCallback integrates the store with a Lightning Trainer: it creates the run at fit start, records the selected logger's tracking metadata, embeds the research run ID in checkpoints, resolves the checkpoint to record, and marks the run completed or failed. Configuration is described in getting started.

research_tracker.callbacks.ResearchTrackerCallback

Bases: Callback

Create and maintain a research-tracker run for a Lightning fit.

Names, configuration paths, logger metadata, and checkpoints are resolved from standard Lightning interfaces. Explicit constructor values always take precedence over inferred values.

Source code in src/research_tracker/callbacks.py
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class ResearchTrackerCallback(Callback):
    """Create and maintain a research-tracker run for a Lightning fit.

    Names, configuration paths, logger metadata, and checkpoints are resolved
    from standard Lightning interfaces. Explicit constructor values always take
    precedence over inferred values.
    """

    def __init__(
        self,
        store_root: str | Path | None = None,
        model: str | None = None,
        dataset: str | None = None,
        dataset_version: str | None = None,
        *,
        config_path: str | Path | None = None,
        config_filename: str = "config.yaml",
        checkpoint_policy: CheckpointPolicy = "best_or_last",
        logger_index: int = 0,
        loader: str | None = None,
        parent_run_id: str | None = None,
        resume_mode: ResumeMode = "continue",
        track_fast_dev_runs: bool = False,
    ) -> None:
        super().__init__()

        if Path(config_filename).name != config_filename:
            raise ValueError("config_filename must be a filename, not a path")
        if checkpoint_policy not in {"best", "last", "best_or_last", "none"}:
            raise ValueError(f"Unknown checkpoint policy: {checkpoint_policy}")
        if logger_index < 0:
            raise ValueError("logger_index must be non-negative")
        if resume_mode not in {"continue", "fork"}:
            raise ValueError(f"Unknown resume mode: {resume_mode}")

        self.store_root = Path(store_root) if store_root is not None else None
        self.model = model
        self.dataset = dataset
        self.dataset_version = dataset_version
        self.config_path = Path(config_path) if config_path is not None else None
        self.config_filename = config_filename
        self.checkpoint_policy = checkpoint_policy
        self.logger_index = logger_index
        self.loader = loader
        self.parent_run_id = parent_run_id
        self.resume_mode = resume_mode
        self.track_fast_dev_runs = track_fast_dev_runs

        self._store: ExperimentStore | None = None
        self._run_id: str | None = None
        self._checkpoint_run_id: str | None = None
        self._tracking = False

    @property
    def store(self) -> ExperimentStore:
        if self._store is None:
            if self.store_root is None:
                raise RuntimeError("Store root has not been resolved yet")
            self._store = ExperimentStore(self.store_root)
        return self._store

    @property
    def run_id(self) -> str:
        if self._run_id is None:
            raise RuntimeError("Run has not been created yet")
        return self._run_id

    def on_load_checkpoint(
        self,
        trainer: Trainer,
        pl_module: LightningModule,
        checkpoint: dict[str, Any],
    ) -> None:
        metadata = checkpoint.get("research_tracker", {})
        self._checkpoint_run_id = _text(metadata.get("run_id"))

    def on_fit_start(self, trainer: Trainer, pl_module: LightningModule) -> None:
        self._tracking = self.track_fast_dev_runs or not trainer.fast_dev_run
        if not self._tracking:
            return

        run_id = None
        if trainer.is_global_zero:
            self._resolve_store_root(trainer)
            run_id = self._start_or_resume_run(trainer, pl_module)
            self._log_run_id(trainer, run_id)

        self._run_id = self._broadcast(trainer, run_id)

    def on_fit_end(self, trainer: Trainer, pl_module: LightningModule) -> None:
        if not self._should_write(trainer):
            return

        checkpoint_path = self._resolve_checkpoint_path(trainer)
        if checkpoint_path is not None:
            self.store.add_checkpoint(checkpoint_path, self.run_id)

        self.store.set_status(Status.COMPLETED, self.run_id)

    def on_save_checkpoint(
        self,
        trainer: Trainer,
        pl_module: LightningModule,
        checkpoint: dict[str, Any],
    ) -> None:
        if not self._tracking or self._run_id is None:
            return

        metadata = {
            "run_id": self.run_id,
            "model_class": _class_path(pl_module),
        }
        if trainer.datamodule is not None:
            metadata["datamodule_class"] = _class_path(trainer.datamodule)

        checkpoint["research_tracker"] = metadata

    def on_exception(
        self,
        trainer: Trainer,
        pl_module: LightningModule,
        exception: BaseException,
    ) -> None:
        if self._should_write(trainer):
            self.store.set_status(Status.FAILED, self.run_id)

    def _start_or_resume_run(
        self,
        trainer: Trainer,
        pl_module: LightningModule,
    ) -> str:
        if (
            self.resume_mode == "continue"
            and self._checkpoint_run_id is not None
            and self._store_contains_run(self._checkpoint_run_id)
        ):
            self.store.set_status(Status.RUNNING, self._checkpoint_run_id)
            return self._checkpoint_run_id

        datamodule = trainer.datamodule
        logger = self._selected_logger(trainer)
        tracking_backend, tracking_id, tracking_project = self._logger_metadata(logger)
        config_path = self._resolve_config_path(trainer)

        model_name = self.model or _text(getattr(pl_module, "model_name", None))
        dataset_name = self.dataset
        dataset_version = self.dataset_version

        if datamodule is not None:
            dataset_name = dataset_name or _text(
                getattr(datamodule, "dataset_name", None)
            )
            dataset_version = dataset_version or _text(
                getattr(datamodule, "dataset_version", None)
            )

        run = self.store.create_run(
            model=model_name or pl_module.__class__.__name__,
            model_class=_class_path(pl_module),
            dataset=dataset_name
            or (datamodule.__class__.__name__ if datamodule is not None else "unknown"),
            config=config_path,
            status=Status.RUNNING,
            seed=self._resolve_seed(),
            tracking_backend=tracking_backend,
            tracking_id=tracking_id,
            tracking_project=tracking_project,
            loader=self.loader,
            dataset_version=dataset_version,
            datamodule_class=(
                _class_path(datamodule) if datamodule is not None else None
            ),
            parent_run_id=self.parent_run_id or self._checkpoint_run_id,
        )
        return run.run_id

    def _resolve_store_root(self, trainer: Trainer) -> None:
        if self.store_root is not None:
            return

        default_root = getattr(trainer, "default_root_dir", None)
        if not isinstance(default_root, (str, PathLike)):
            raise RuntimeError(
                "Could not infer the store root from trainer.default_root_dir"
            )
        self.store_root = Path(default_root)

    def _resolve_config_path(self, trainer: Trainer) -> Path:
        if self.config_path is not None:
            if not self.config_path.is_file():
                raise FileNotFoundError(self.config_path)
            return self.config_path

        candidates: list[Path] = []
        for logger in self._loggers(trainer):
            experiment = getattr(logger, "experiment", None)
            self._add_config_candidate(candidates, experiment, "dir")
            self._add_config_candidate(candidates, logger, "log_dir")
            self._add_config_candidate(candidates, logger, "save_dir")

        self._add_config_candidate(candidates, trainer, "default_root_dir")

        for candidate in candidates:
            if candidate.is_file():
                return candidate

        searched = ", ".join(str(path) for path in candidates) or "<none>"
        raise FileNotFoundError(
            f"Could not find {self.config_filename}. Searched: {searched}. "
            "Pass config_path explicitly when the configuration is stored elsewhere."
        )

    def _add_config_candidate(
        self,
        candidates: list[Path],
        owner: object | None,
        attribute: str,
    ) -> None:
        if owner is None:
            return

        value = getattr(owner, attribute, None)
        if callable(value):
            value = value()
        if not isinstance(value, (str, PathLike)):
            return

        candidate = Path(value) / self.config_filename
        if candidate not in candidates:
            candidates.append(candidate)

    def _loggers(self, trainer: Trainer) -> list[Any]:
        loggers = getattr(trainer, "loggers", None)
        if loggers:
            return list(loggers)

        logger = getattr(trainer, "logger", None)
        return [] if logger is None or logger is False else [logger]

    def _selected_logger(self, trainer: Trainer) -> Any | None:
        loggers = self._loggers(trainer)
        if not loggers:
            return None
        if self.logger_index >= len(loggers):
            raise IndexError(
                f"logger_index={self.logger_index} but Trainer has "
                f"{len(loggers)} logger(s)"
            )
        return loggers[self.logger_index]

    def _logger_metadata(
        self,
        logger: Any | None,
    ) -> tuple[str | None, str | None, str | None]:
        if logger is None:
            return None, None, None

        experiment = getattr(logger, "experiment", None)
        tracking_id = _text(getattr(experiment, "id", None)) or _text(
            getattr(logger, "version", None)
        )
        tracking_project = _text(getattr(experiment, "project", None)) or _text(
            getattr(logger, "name", None)
        )
        return logger.__class__.__qualname__, tracking_id, tracking_project

    def _log_run_id(self, trainer: Trainer, run_id: str) -> None:
        logger = self._selected_logger(trainer)
        if logger is None:
            return

        log_hyperparams = getattr(logger, "log_hyperparams", None)
        if not callable(log_hyperparams):
            return

        try:
            log_hyperparams({"research_run_id": run_id})
        except Exception as error:
            warnings.warn(
                f"Could not add research_run_id to the logger: {error}",
                RuntimeWarning,
                stacklevel=2,
            )

    def _resolve_checkpoint_path(self, trainer: Trainer) -> Path | None:
        if self.checkpoint_policy == "none":
            return None

        checkpoints = [
            callback
            for callback in trainer.callbacks
            if isinstance(callback, ModelCheckpoint)
        ]
        best = [
            Path(callback.best_model_path)
            for callback in checkpoints
            if callback.best_model_path
        ]
        last = [
            Path(callback.last_model_path)
            for callback in checkpoints
            if callback.last_model_path
        ]

        if self.checkpoint_policy == "best":
            return best[0] if best else None
        if self.checkpoint_policy == "last":
            return last[0] if last else None
        return (best or last or [None])[0]

    def _store_contains_run(self, run_id: str) -> bool:
        return self.store.has_run(run_id)

    def _should_write(self, trainer: Trainer) -> bool:
        return self._tracking and trainer.is_global_zero and self._run_id is not None

    @staticmethod
    def _resolve_seed() -> int | None:
        seed = os.environ.get("PL_GLOBAL_SEED")
        if seed is None:
            return None
        try:
            return int(seed)
        except ValueError:
            warnings.warn(
                f"Ignoring invalid PL_GLOBAL_SEED value: {seed!r}",
                RuntimeWarning,
                stacklevel=2,
            )
            return None

    @staticmethod
    def _broadcast(trainer: Trainer, run_id: str | None) -> str | None:
        broadcast = getattr(getattr(trainer, "strategy", None), "broadcast", None)
        return broadcast(run_id) if callable(broadcast) else run_id

Types

research_tracker.callbacks.CheckpointPolicy = Literal['best', 'last', 'best_or_last', 'none'] module-attribute

research_tracker.callbacks.ResumeMode = Literal['continue', 'fork'] module-attribute