Add _update_metadata() method to CheckpointHandlers.

checkpoint/CHANGELOG.md

@@ -36,6 +36,7 @@ when a custom `snapshot_dir` is specified.
 `CompositeCheckpointHandler.metadata()` to retrieve item metadata by
 default-constructing `CheckpointHandler`s when they're listed in the saved
 `StepMetadata` but aren't found in the checkpoint.
+- `FileOptions.format` to specify the underlying checkpointing file format.
 
 ### Fixed
 - Ignore not-exists and not-dir errors while building step metadata in
@@ -44,6 +45,7 @@ default-constructing `CheckpointHandler`s when they're listed in the saved
 
 ### Changed
 - Return `StepMetadata` from `CompositeCheckpointHandler.metadata()`.
+- `Checkpointer.save()` also saves `StepMetadata`.
 
 ## [0.10.2] - 2024-12-04
 

checkpoint/orbax/checkpoint/_src/checkpointers/checkpointer.py

@@ -29,6 +29,7 @@
 from orbax.checkpoint._src.handlers import checkpoint_handler
 from orbax.checkpoint._src.handlers import composite_checkpoint_handler
 from orbax.checkpoint._src.metadata import checkpoint
+from orbax.checkpoint._src.metadata import step_metadata_serialization
 from orbax.checkpoint._src.multihost import multihost
 from orbax.checkpoint._src.path import atomicity
 from orbax.checkpoint._src.path import atomicity_defaults
@@ -42,6 +43,7 @@
 get_legacy_handler_wrapper = (
     composite_checkpoint_handler.get_legacy_handler_wrapper
 )
+StepMetadata = checkpoint.StepMetadata
 
 
 def construct_checkpoint_args(
@@ -161,7 +163,12 @@ async def create_temporary_path(
     return tmpdir
 
   def save(
-      self, directory: epath.PathLike, *args, force: bool = False, **kwargs
+      self,
+      directory: epath.PathLike,
+      *args,
+      force: bool = False,
+      custom_metadata: dict[str, Any] | None = None,
+      **kwargs,
   ):
     """Saves the given item to the provided directory.
 
@@ -176,6 +183,8 @@ def save(
       *args: additional args to provide to the CheckpointHandler's save method.
       force: if True, allows overwriting an existing directory. May add overhead
         due to the need to delete any existing files.
+      custom_metadata: a dictionary of custom metadata to be written to the
+        checkpoint directory via StepMetadata.
       **kwargs: additional keyword args to provide to the CheckpointHandler's
         save method.
 
@@ -210,6 +219,17 @@ def save(
         processes=self._active_processes,
     )
 
+    if utils.is_primary_host(self._primary_host):
+      self._save_step_metadata(tmpdir.get(), custom=custom_metadata)
+    multihost.sync_global_processes(
+        multihost.unique_barrier_key(
+            'Checkpointer:step_metadata_save',
+            prefix=self._barrier_sync_key_prefix,
+            # suffix=tmpdir.get().name,
+        ),
+        processes=self._active_processes,
+    )
+
     # Ensure save operation atomicity and record time saved by checkpoint.
     if utils.is_primary_host(self._primary_host):
       self._handler.finalize(tmpdir.get())
@@ -251,11 +271,25 @@ def _restore(
   ) -> Any:
     return self._handler.restore(directory, args=args)
 
-  def metadata(self, directory: epath.PathLike) -> Optional[Any]:
+  def metadata(self, directory: epath.PathLike) -> StepMetadata | Any | None:
     """See superclass documentation."""
     directory = epath.Path(directory)
     return self._handler.metadata(directory)
 
+  def _save_step_metadata(
+      self, directory: epath.Path, custom: dict[str, Any] | None
+  ):
+    """Saves StepMetadata to the checkpoint directory."""
+    step_metadata = StepMetadata(
+        format=self._file_options.format,
+        custom=custom,
+    )
+    self._handler._update_metadata(directory, step_metadata)  # pylint: disable=protected-access
+    self._metadata_store.update(
+        file_path=checkpoint.step_metadata_file_path(directory),
+        **step_metadata_serialization.serialize(step_metadata),
+    )
+
   def close(self):
     """Closes the underlying CheckpointHandler."""
     self._handler.close()

checkpoint/orbax/checkpoint/_src/handlers/checkpoint_handler.py

@@ -18,6 +18,8 @@
 from typing import Any, Optional
 from etils import epath
 
+from orbax.checkpoint._src.metadata import checkpoint
+
 
 class CheckpointHandler(abc.ABC):
   """An interface providing save/restore methods used on a savable item.
@@ -67,6 +69,13 @@ def metadata(self, directory: epath.Path) -> Optional[Any]:
     """
     pass
 
+  def _update_metadata(self, directory: epath.Path, step_metadata: Any) -> None:
+    """Updates `item_handlers` in `step_metadata`."""
+    del directory
+    step_metadata.item_handlers: checkpoint.CheckpointHandlerTypeStr = (
+        self.typestr()
+    )
+
   def finalize(self, directory: epath.Path) -> None:
     """Optional, custom checkpoint finalization callback.
 
@@ -84,4 +93,4 @@ def close(self):
   @classmethod
   def typestr(cls) -> str:
     """A unique identifier for the CheckpointHandler type."""
-    return f"{cls.__module__}.{cls.__qualname__}"
+    return f'{cls.__module__}.{cls.__qualname__}'

checkpoint/orbax/checkpoint/_src/handlers/composite_checkpoint_handler.py

@@ -902,6 +902,19 @@ def metadata(self, directory: epath.Path) -> StepMetadata:
         item_metadata=CompositeItemMetadata(**item_metadata),
     )
 
+  def _update_metadata(self, directory: epath.Path, step_metadata: Any) -> None:
+    """Updates `item_handlers` in `step_metadata`."""
+    try:
+      partial_metadata: StepMetadata = self.metadata(directory)
+    except (FileNotFoundError, NotImplementedError, ValueError):
+      logging.warning(
+          'Failed to get per-item metadata from directory %s. Handler types '
+          'will not be saved.',
+          directory,
+      )
+    else:
+      step_metadata.item_handlers = partial_metadata.item_handlers
+
   def finalize(self, directory: epath.Path):
     if not self._current_temporary_paths:
       raise ValueError('finalize() called before any items were saved.')

checkpoint/orbax/checkpoint/options.py

@@ -21,6 +21,9 @@
 
 
 
+_ORBAX_STANDARD_FORMAT = 'orbax-standard'
+
+
 @dataclasses.dataclass
 class AsyncOptions:
   """Options used to configure async behavior.
@@ -65,9 +68,13 @@ class FileOptions:
       metadata files. e.g. 0o750. Please check
       https://github.com/google/etils/blob/main/etils/epath/backend.py if your
         path is supported. default=None.
+    format: The checkpoint file format. This is useful when differentiating
+      between Orbax and Roc checkpoints, as well as checkpoints saved by
+      different apis. Defaults to 'orbax-standard'.
   """
 
   path_permission_mode: Optional[int] = None
+  format: str = _ORBAX_STANDARD_FORMAT