-------------
Release date: 2020-09-24
This is a feature release of Traits Futures. The main features of this
release are:
* Improved support for user-defined background task types.
* Easier creation of background calculations that can be (cooperatively)
cancelled mid-calculation.
* Significant internal refactoring and cleanup, aimed at eventual support
for alternative front ends (GUI event loops other than the Qt event
loop) and back ends (e.g., multiprocessing).
* Improved and expanded documentation.
There are no immediately API-breaking changes in this release: existing working
code using Traits Futures 0.1.1 should continue to work with no changes
required. However, some parts of the existing API have been deprecated, and
will be removed in a future release. See the Changes section below for more
details.
Detailed changes follow. Note that the list below is not exhaustive: many
more minor PRs have been omitted.
Features
~~~~~~~~
* Users can now easily create their own background task types to supplement
the provided task types (background calls, background iterations and
background progress). A combination of a new :class:`ITaskSpecification`
interface and a convenience :class:`BaseFuture` base class support this.
(198)
* The :func:`submit_iteration` function now supports generator functions that
return a result. This provides an easy way to submit background computations
that can be cancelled mid-calculation. (167)
* The :class:`TraitsExecutor` class now accepts a ``max_workers`` argument,
which specifies the maximum number of workers for a worker pool created
by the executor. (125)
* There are new task submission functions :func:`submit_call`,
:func:`submit_iteration` and :func:`submit_progress`. These functions replace
the eponymous existing :class:`TraitsExecutor` methods, which are now
deprecated. (166)
* There's a new :class:`IFuture` interface class in the
:mod:`traits_futures.api` module, to aid in typing and Trait declarations.
(169)
* A new :class:`IParallelContext` interface supports eventual addition
of alternative back ends. The new :class:`MultithreadingContext` class
implements this interface and provides the default threading back-end.
(149)
Changes
~~~~~~~
* The default number of workers in an owned worker pool (that is, a worker pool
created by a :class:`TraitsExecutor`) has changed. Previously it was
hard-coded as ``4``. Now it defaults to whatever Python's
:mod:`concurrent.futures` executors give, but can be controlled by passing
the ``max_workers`` argument. (125)
* The ``submit_call``, ``submit_iteration`` and ``submit_progress``
methods on the :class:`TraitsExecutor` have been deprecated. Use the
:func:`submit_call`, :func:`submit_iteration` and :func:`submit_progress`
convenience functions instead. (159)
* The ``thread_pool`` argument to :class:`TraitsExecutor` has been renamed
to ``worker_pool``. The original name is still available for backwards
compatibility, but its use is deprecated. (144, 148)
* Python 2.7 is no longer supported. Traits Futures requires Python >= 3.5,
and has been tested with Python 3.5 through Python 3.9. (123, 130, 131,
132, 133, 138, 145)
Fixes
~~~~~
* Don't create a new MessageRouter at executor shutdown time. (187)
Tests
~~~~~
* Fix some intermittent test failures due to test interactions. (176)
* The 'null' backend that's used for testing in the absence of a Qt backend
now uses a :mod:`asyncio`-based event loop instead of a custom event loop.
(107, 179)
* Rewrite the Qt ``GuiTestAssistant`` to react rather than polling. This
significantly speeds up the test run. (153)
* Ensure that all tests properly stop the executors they create. (108, 146)
* Refactor the test structure in preparation for multiprocessing
support. (135, 141)
* Test the ``GuiTestAssistant`` class. (109)
Developer tooling
~~~~~~~~~~~~~~~~~
* Add a new ``python -m ci shell`` click cmd. (204)
* Update edm version in CI. (205)
* Add checks for missing or malformed copyright headers in Python files (and
fix existing copyright headers). (193)
* Add import order checks (and fix existing import order bugs). (161)
* Add separate "build" and "ci" modes for setting up the development
environment. (104)
* Don't pin dependent packages in the build environment. (99)
Documentation
~~~~~~~~~~~~~
* Update docs to use the Enthought Sphinx Theme. (128)
* Autogenerated API documentation is now included in the documentation
build. (177, 181)
* Restructure the documentation to avoid nesting 'User Guide'
under 'User Documentation'. (191)
* Document creation of new background task types. (198)
* Document use of ``submit_iteration`` for interruptible tasks. (188)