A tff.program.ReleaseManager that releases values to a CSV file.

Inherits From: ReleaseManager

A tff.program.CSVFileReleaseManager is a utility for releasing values from a federated program to a CSV file and is used to release values from platform storage to customer storage in a federated program.

Values are released to the file system as a CSV file and are quoted as strings. When the value is released, if the value is a value reference or a structure containing value references, each value reference is materialized. The value is then flattened, converted to a numpy.ndarray, and then converted to a nested list of Python scalars, and released as a CSV file. For example, 1 will be written as '1' and tf.constant([[1, 1], [1, 1]]) will be written as '[[1, 1], [1, 1]]'.

This manager can be configured to release values using a save_mode of either CSVSaveMode.APPEND or CSVSaveMode.WRITE.

  • In append mode, when a value is released, this manager will try and append the value to the CSV file instead of overwriting the existing file. While potentially more efficient, append mode is incompatible with compressed files (e.g. .bz2 formats) and encoded directories. This mode is equivalent to write mode when releasing a value with a different structure than the currently released values, so it may not be useful when values with different structures are being released frequently.

  • In write mode (or in append mode when releasing new structures), when a value is realeased, this manager reads the entire CSV file and overwrites the existing file with the additional values. This can be slower than append mode, but is compatible with compressed files (e.g. .bz2 formats) and encoded directories.

file_path A path on the file system to save releases values. If this file does not exist it will be created.
save_mode A tff.program.CSVSaveMode specifying how to save released values.
key_fieldname A str specifying the fieldname used for the key when saving released value.

ValueError If file_path or key_fieldname is an empty string.
CSVKeyFieldnameNotFoundError If the file exists but does not contain a fieldname of key_fieldname.



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Releases value from a federated program.

This method will atomically update the managed CSV file by removing all values previously released with a key greater than or equal to key before writing value.

value A tff.program.ReleasableStructure to release.
key An integer used to reference the released value; key represents a step in a federated program.