TensorFlow Federated 0.84.0

Release 0.84.0

Added

• Added some TFF executor classes to the public API (ComposingExecutor,
  ExecutorTestBase, MockExecutor, ThreadPool).
• Added some compiler transformation helper functions to the public API
  (replace_intrinsics_with_bodies, unique_name_generator,
  transform_preorder, to_call_dominant).
• Added a method to get the number of checkpoints aggregated to the
  CheckpointAggregator API.
• The function DPClosedDomainHistogram::IncrementDomainIndices. It allows
  calling code to iterate through the domain of composite keys (in a do-while
  loop).

Changed

• Fixed a bug in tff.jax.computation that raised an error when the
  computation had unused arguments.
• Fixed a bug when using tff.backends.xla execution stack that raised errors
  when single element structures were returned from tff.jax.computation
  wrapped methods.
• Modified the model output release frequency to every 10 rounds and the final
  round in tff.learning.programs.train_model.
• Loosened the kEpsilonThreshold constant and updated the tests of
  DPOpenDomainHistogram accordingly.
• The behavior of DPClosedDomainHistogram::Report(): it now produces an
  aggregate for each possible combinations of keys. Those composite keys that
  GroupByAggregator did not already assign an aggregate to are assigned 0.
  Future CL will add noise.
• Modified tff.learning.algorithms.build_weighted_fed_avg to generate
  different training graphs when use_experimental_simulation_loop=True and
  model_fn is of type tff.learning.models.FunctionalModel.