tff.program.ProgramStateManager

An interface for saving and loading program state in a federated program.

A tff.program.ProgramStateManager is used to implement fault tolerance in a federated program. The structure or type of the program state that is saved is unknown at construction time and can change as the program runs.

Methods

`get_versions`

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get_versions()

Returns a list of saved versions or None.

Returns
A list of saved versions or `None` if there is no saved program state.

`load`

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load(
    version, structure
)

Returns the saved program state for the given version.

Args
`version`	A integer representing the version of a saved program state.
`structure`	The structure of the saved program state for the given `version` used to support serialization and deserailization of user-defined classes in the structure.

Raises
`ProgramStateNotFoundError`	If there is no program state for the given `version`.

`load_latest`

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load_latest(
    structure
)

Returns the latest saved program state and version or (None, 0).

Args
`structure`	The structure of the saved program state for the given `version` used to support serialization and deserailization of user-defined classes in the structure.

Returns
A tuple of the latest saved (program state, version) or (`None`, 0) if there is no latest saved program state.

`save`

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save(
    program_state, version
)

Saves program_state for the given version.

Args
`program_state`	A `tff.program.ProgramStateStructure` to save.
`version`	A strictly increasing integer representing the version of a saved `program_state`.

Raises
`ProgramStateExistsError`	If there is already program state for the given `version`.