Tensorflow-federated

Major Features and Improvements

* Added an async XLA runtime under `tff.backends.xla`.

Breaking Changes

* Updated `tensorflow-privacy` version to `0.9.0`.
* Removed the deprecated `type_signature` parameter from the
`tff.program.ReleaseManager.release` method.

Major Features and Improvements

* Added new environment-specific packages to TFF.

Breaking Changes

* Temporarily disable `tff.program.PrefetchingDataSource` due to flakiness
from a lack of determinism.
* Removed support for invoking `infer_type` with TensorFlow values.
* Removed deprecated `tff.aggregators.federated_(min|max)`symbols, please use
`tff.federated_(min|max)` instead.
* Removed support for creating a `tff.TensorType` using a `tf.dtypes.DType`.
* Removed `tff.check_return_type`.

Bug Fixes

* Declared `OwnedValueId::INVALID_ID` as a static constexpr.

Major Features and Improvements

* The `local_unfinalized_metrics_type` argument to
tff.learning.metrics.(secure_)sum_then_finalize is now optional (and is not
actually used). It will be removed in a future release.

Breaking Changes

* tff.learning.metrics.(secure_)sum_then_finalize now return polymorphic
computations. They can still be passed into algorithm builders (e.g.
tff.learning.algorithms.build_weighted_fed_avg) but to be called directly
they must first be traced with explicit types.
* Removed support for handling `tf.TensorSpec` using `to_type`, use
`tensorflow_to_type` instead.
* Removed support for calling `tff.TensorType` using a `tf.dtypes.DType`.

Major Features and Improvements

* Added `tff.types.tensorflow_to_type` function to convert structures
containing tensorflow type specs into a `tff.Type`.
* Deprecated `tff.types.infer_unplaced_type`.
* Updated `tff.types.ArrayShape` to be defined as a `Sequence` not an
`Iterable`, this is because the `len` of an `tff.types.ArrayShape` is used
for comparison.
* Deprecated the `type_signature` parameter for the
`tff.program.ReleaseManager.release` method.

Breaking Changes

* Removed the implementation of `tff.Value.__add__`.
* Removed the deprecated `tff.Type.check_*()` functions, use `isinstance`
instead.
* Removed `tff.types.at_clients` and `tff.types.at_server` functions, use the
`tff.FederatedType` constructor instead.
* Removed support for handling `tf.data.DatasetSpec`, `tf.RaggedTensorSpec`,
and `tf.SparseTensorSpec` using `tff.to_type`, use
`tff.types.tensorflow_to_type` instead.
* Removed support for handling `tf.RaggedTensor` and `tf.SparseTensor` using
`infer_type`.

Major Features and Improvements

* Updated the representation of a tff.TensorType.dtype to be a `np.dtype`
instead of `tf.dtypes.Dtype`.
* Added `tff.program.DelayedReleaseManager`.

Breaking Changes

* Removed `check_allowed_ops` from the `framework` package.
* Removed `check_disallowed_ops` from the `framework` package.
* Removed `replace_intrinsics_with_bodies` from the `framework` package.
* Removed `get_session_token` from the `framework` package.
* Added a workspace dependency on `pybind11_bazel`.
* Removed `type_from_tensors` from the `framework` package.
* Updated the version of `rules_python` to `0.23.0`.

Bug Fixes

* Temporary pin `googleapis-common-protos` to version `1.61.0` to work around
an issue with a transitive dependency.