Source code for orbax.checkpoint.experimental.v1._src.layout.registry

# Copyright 2026 The Orbax Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
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"""Registry for checkpoint layouts."""
from __future__ import annotations

import asyncio

from absl import logging
from orbax.checkpoint._src import asyncio_utils
from orbax.checkpoint.experimental.v1._src.context import context as context_lib
from orbax.checkpoint.experimental.v1._src.context import options as options_lib
from orbax.checkpoint.experimental.v1._src.layout import checkpoint_layout
from orbax.checkpoint.experimental.v1._src.layout import orbax_layout
from orbax.checkpoint.experimental.v1._src.layout import orbax_v0_layout
from orbax.checkpoint.experimental.v1._src.layout import safetensors_layout
from orbax.checkpoint.experimental.v1._src.path import types as path_types


InvalidLayoutError = checkpoint_layout.InvalidLayoutError
CheckpointLayout = checkpoint_layout.CheckpointLayout
CheckpointLayoutEnum = options_lib.CheckpointLayout

ORBAX_LAYOUT_CLASSES = [
    orbax_layout.OrbaxLayout,
    orbax_v0_layout.OrbaxV0Layout,
]


async def _is_orbax_checkpoint_async(path: path_types.PathLike) -> bool:
  ctx = context_lib.get_context()
  path = ctx.file_options.path_class(path)

  tasks = []
  for layout_cls in ORBAX_LAYOUT_CLASSES:
    tasks.append(layout_cls().validate(path))

  results = await asyncio.gather(*tasks, return_exceptions=True)
  return any(not isinstance(r, Exception) for r in results)




def is_orbax_checkpoint(path: path_types.PathLike) -> bool:
  """Returns True if the path is an Orbax checkpoint."""
  return asyncio_utils.run_sync(_is_orbax_checkpoint_async(path))



async def get_layout_class(
    layout_enum: CheckpointLayoutEnum, path: path_types.PathLike | None = None
) -> type[CheckpointLayout]:
  """Returns the layout class for the given layout enum."""
  match layout_enum:
    case CheckpointLayoutEnum.ORBAX:
      if path is None or (
          await orbax_layout.checkpoint_version(path)
          == orbax_layout.CheckpointVersion.V1
      ):
        return orbax_layout.OrbaxLayout
      else:
        return orbax_v0_layout.OrbaxV0Layout
    case CheckpointLayoutEnum.SAFETENSORS:
      return safetensors_layout.SafetensorsLayout
    case _:
      raise ValueError(f"Unsupported checkpoint layout: {layout_enum}")


async def get_checkpoint_layout(
    path: path_types.PathLike, layout_enum: CheckpointLayoutEnum
) -> CheckpointLayout:
  """Returns the checkpoint layout class for the given path and validates it.

  Args:
    path: The path to the checkpoint.
    layout_enum: The checkpoint layout to use.

  Returns:
    The class of the matching :py:class:`.CheckpointLayout`.

  Raises:
    InvalidLayoutError: If the path is not a valid checkpoint for any registered
    layout, with details from each layout's validation attempt.
  """

  ctx = context_lib.get_context()
  path = ctx.file_options.path_class(path)

  layout_class = await get_layout_class(layout_enum, path)

  try:
    layout = layout_class()
    await layout.validate(path)
    return layout
  except InvalidLayoutError as e:
    raise InvalidLayoutError(
        f"Could not recognize the checkpoint at {path} as a valid"
        f" {layout_enum.value} checkpoint. If you are trying to load a"
        " checkpoint that does not conform to the standard Orbax format, use"
        " `ctx.checkpoint_layout = ...` to specify the expected checkpoint"
        " layout."
    ) from e


class CheckpointLayoutResolver:
  """Resolves the layout and pytree name for a checkpoint."""

  def __init__(
      self,
      path: path_types.PathLike,
      layout_enum: CheckpointLayoutEnum,
      layout: CheckpointLayout,
      resolved_pytree_name: str | None,
  ):
    self._path = path
    self._layout_enum = layout_enum
    self._layout = layout
    self._resolved_pytree_name = resolved_pytree_name

  @classmethod
  async def resolve(
      cls,
      path: path_types.PathLike,
      layout_enum: CheckpointLayoutEnum,
      *,
      pytree_name: str | None = None,
  ) -> CheckpointLayoutResolver:
    """Resolves the layout and pytree name for a checkpoint.

    Args:
      path: The path to the checkpoint.
      layout_enum: The checkpoint layout to use.
      pytree_name: The name of the pytree to load. If
        `checkpoint_layout.AUTO_CHECKPOINTABLE_KEY`, the name will be
        auto-resolved.

    Returns:
      A CheckpointLayoutResolver instance.

    Raises:
      InvalidLayoutError: If the checkpoint layout is invalid or if a valid
        PyTree checkpointable cannot be found.
    """
    ctx = context_lib.get_context()
    path = ctx.file_options.path_class(path)

    layout = await get_checkpoint_layout(path, layout_enum)
    if pytree_name == checkpoint_layout.AUTO_CHECKPOINTABLE_KEY:
      names = await layout.get_checkpointable_names(path)
      for name in names:
        try:
          await layout.validate_pytree(path, name)
          logging.info(
              "AUTO resolution mode successfully identified a pytree with"
              " checkpointable name '%s' at path '%s'. Attempting to load with"
              " this name. If this is not the desired checkpointable, please"
              " specify the name explicitly.",
              name,
              path,
          )
          return cls(path, layout_enum, layout, name)
        except InvalidLayoutError:
          continue

      if isinstance(layout, orbax_v0_layout.OrbaxV0Layout):
        try:
          await layout.validate_pytree(path, None)
          logging.info(
              "AUTO resolution mode successfully identified a pytree at path"
              " '%s'. Attempting to load as a flat layout V0 Orbax checkpoint."
              " with checkpointable_name=None.",
              path,
          )
          return cls(path, layout_enum, layout, None)
        except InvalidLayoutError:
          pass

      raise InvalidLayoutError(
          "Failed to load checkpoint using AUTO resolution mode on"
          f" path='{path}'. No valid PyTree checkpointable found."
      ) from None

    await layout.validate_pytree(path, pytree_name)
    return cls(path, layout_enum, layout, pytree_name)

  @property
  def layout(self) -> CheckpointLayout:
    """Returns the checkpoint layout."""
    return self._layout

  @property
  def pytree_name(self) -> str | None:
    """Returns the resolved pytree name."""
    return self._resolved_pytree_name