tornado/website/sphinx/releases/next.rst

What's new in the next release of Tornado
=========================================

In progress
-----------

* The Tornado test suite now requires ``unittest2`` when run on Python 2.5
  or 2.6.
* `tornado.testing.AsyncTestCase` and friends now extend ``unittest2.TestCase``
  when it is available (and continue to use the standard ``unittest`` module
  when ``unittest2`` is not available)
* `tornado.netutil.bind_sockets` no longer sets ``AI_ADDRCONFIG``; this will
  cause it to bind to both ipv4 and ipv6 more often than before.
* `tornado.netutil.bind_sockets` has a new ``flags`` argument that can
  be used to pass additional flags to ``getaddrinfo``.
* Tornado no longer logs to the root logger.  Details on the new logging
  scheme can be found under the `tornado.log` module.  Note that in some
  cases this will require that you add an explicit logging configuration
  in ordre to see any output (perhaps just calling ``logging.basicConfig()``),
  although both `IOLoop.start()` and `tornado.options.parse_command_line`
  will do this for you.
* Errors while rendering templates no longer log the generated code,
  since the enhanced stack traces (from version 2.1) should make this
  unnecessary.
* `tornado.testing.ExpectLog` can be used as a finer-grained alternative
  to `tornado.testing.LogTrapTestCase`
* The command-line interface to `tornado.testing.main` now supports
  additional arguments from the underlying `unittest` module:
  ``verbose``, ``quiet``, ``failfast``, ``catch``, ``buffer``.
* Empty HTTP request arguments are no longer ignored.  This applies to
  ``HTTPRequest.arguments`` and ``RequestHandler.get_argument[s]``
  in WSGI and non-WSGI modes.
* New function `tornado.testing.bind_unused_port` both chooses a port
  and binds a socket to it, so there is no risk of another process
  using the same port.  ``get_unused_port`` is now deprecated.
* The `tornado.database` module has been removed.  It is now available
  as a separate package, `torndb <https://github.com/bdarnell/torndb>`_
* New class `tornado.iostream.PipeIOStream` provides the IOStream
  interface on pipe file descriptors.
* Much of `IOStream` has been refactored into a separate class
  `BaseIOStream`.
* New class `tornado.process.Subprocess` wraps `subprocess.Popen` with
  `PipeIOStream` access to the child's file descriptors.
* `IOLoop` now uses `signal.set_wakeup_fd` where available (Python 2.6+
  on Unix) to avoid a race condition that could result in Python signal
  handlers being delayed.
* `WebSocketHandler` has new methods `ping` and `on_pong` to send pings
  to the browser (not supported on the ``draft76`` protocol)
* The ``Date`` HTTP header is now set by default on all responses.
* Several methods related to HTTP status codes now take a ``reason`` keyword
  argument to specify an alternate "reason" string (i.e. the "Not Found" in
  "HTTP/1.1 404 Not Found").  It is now possible to set status codes other
  than those defined in the spec, as long as a reason string is given.
* New method `IOLoop.add_callback_from_signal` is safe to use in a signal
  handler (the regular `add_callback` method may deadlock).
* `stack_context.wrap` now runs the wrapped callback in a more consistent
  environment by recreating contexts even if they already exist on the
  stack.
* Fixed a bug in which stack contexts could leak from one callback
  chain to another.
* `tornado.autoreload` is now more reliable when there are errors at import
  time.
* New optional dependency on `concurrent.futures` to provide better support
  for working with threads.  `concurrent.futures` is in the standard library
  for Python 3.2+, and can be installed on older versions with
  ``pip install futures``.
* New module `tornado.concurrent` contains code to support working with
  `concurrent.futures`, or to emulate future-based interface when that module
  is not available.
* New method `IOLoop.add_future` to run a callback on the IOLoop when
  an asynchronous ``Future`` finishes.
* New class `tornado.netutil.Resolver` provides an asynchronous
  interface to `socket.getaddrinfo`.  The interface is based on (but
  does not require) `concurrent.futures`.  When used with
  `concurrent.futures.ThreadPoolExecutor`, it allows for DNS
  resolution without blocking the main thread.
* `SimpleAsyncHTTPClient` now takes a ``resolver`` keyword argument (which
  may be passed to either the constructor or ``configure``), to allow it to
  use the new non-blocking `tornado.netutil.Resolver`.
* Functions using `gen.engine` may now yield ``Future`` objects.
* New function `IOLoop.current` returns the ``IOLoop`` that is running
  on the current thread (as opposed to `IOLoop.instance`, which returns a
  specific thread's (usually the main thread's) IOLoop).
* `tornado.options.parse_config_file` now configures logging automatically
  by default, in the same way that `parse_command_line` does.
* New function `tornado.options.add_parse_callback` schedules a callback
  to be run after the command line or config file has been parsed.  The
  keyword argument ``final=False`` can be used on either parsing function
  to supress these callbacks.
* Function `tornado.options.enable_pretty_logging` has been moved to the
  `tornado.log` module.
* `tornado.options.define` now takes a ``callback`` argument.  This callback
  will be run with the new value whenever the option is changed.  This is
  especially useful for options that set other options, such as by reading
  from a config file.
* `tornado.option.parse_command_line` ``--help`` output now goes to ``stderr``
  rather than ``stdout``.
* The class underlying the functions in `tornado.options` is now public
  (`tornado.options.OptionParser`).  This can be used to create multiple
  independent option sets, such as for subcommands.
* `tornado.options.options` is no longer a subclass of `dict`; attribute-style
  access is now required.
* The ``max_clients`` argument to `AsyncHTTPClient` is now a keyword-only
  argument.
* Keyword arguments to `AsyncHTTPClient.configure` are no longer used
  when instantiating an implementation subclass directly.
* The `IOLoop` poller implementations (``select``, ``epoll``, ``kqueue``)
  are now available as distinct subclasses of `IOLoop`.  Instantiating
  `IOLoop` will continue to automatically choose the best available
  implementation.
* `IOLoop` now has a static ``configure`` method like the one on
  `AsyncHTTPClient`, which can be used to select an IOLoop implementation
  other than the default.
* The deprecated ``--autoreload`` option of `tornado.testing.main` has
  been removed.  Use ``python -m tornado.autoreload`` as a prefix command
  instead.
* The ``--httpclient`` option of `tornado.testing.main` has been moved
  to `tornado.test.runtests` so as not to pollute the application
  option namespace.  The `tornado.options` module's new callback
  support now makes it easy to add options from a wrapper script
  instead of putting all possible options in `tornado.testing.main`.