=========================
Mar 29, 2013
------------
Highlights
^^^^^^^^^^
* The ``callback`` argument to many asynchronous methods is now
optional, and these methods return a `.Future`. The `tornado.gen`
module now understands ``Futures``, and these methods can be used
directly without a `.gen.Task` wrapper.
* 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.
* New class `tornado.netutil.Resolver` provides an asynchronous
interface to DNS resolution. The default implementation is still
blocking, but non-blocking implementations are available using one
of three optional dependencies: `~tornado.netutil.ThreadedResolver`
using the `concurrent.futures` thread pool,
``tornado.platform.caresresolver.CaresResolver`` using the ``pycares``
library, or ``tornado.platform.twisted.TwistedResolver`` using ``twisted``
* Tornado's logging is now less noisy, and it no longer goes directly
to the root logger, allowing for finer-grained configuration.
* New class `tornado.process.Subprocess` wraps `subprocess.Popen` with
`.PipeIOStream` access to the child's file descriptors.
* `.IOLoop` now has a static `configure <.Configurable.configure>`
method like the one on `.AsyncHTTPClient`, which can be used to
select an `.IOLoop` implementation other than the default.
* `.IOLoop` can now optionally use a monotonic clock if available
(see below for more details).
Backwards-incompatible changes
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
* Python 2.5 is no longer supported. Python 3 is now supported in a single
codebase instead of using ``2to3``
* The ``tornado.database`` module has been removed. It is now available
as a separate package, `torndb <https://github.com/bdarnell/torndb>`_
* Functions that take an ``io_loop`` parameter now default to
`.IOLoop.current()` instead of `.IOLoop.instance()`.
* Empty HTTP request arguments are no longer ignored. This applies to
``HTTPRequest.arguments`` and ``RequestHandler.get_argument[s]``
in WSGI and non-WSGI modes.
* On Python 3, `tornado.escape.json_encode` no longer accepts byte strings.
* On Python 3, the ``get_authenticated_user`` methods in `tornado.auth`
now return character strings instead of byte strings.
* ``tornado.netutil.TCPServer`` has moved to its own module,
`tornado.tcpserver`.
* The Tornado test suite now requires ``unittest2`` when run on Python 2.6.
Detailed changes by module
^^^^^^^^^^^^^^^^^^^^^^^^^^
Multiple modules
~~~~~~~~~~~~~~~~
* 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 order to see any output (perhaps just calling ``logging.basicConfig()``),
although both `.IOLoop.start()` and `tornado.options.parse_command_line`
will do this for you.
* On python 3.2+, methods that take an ``ssl_options`` argument (on
`.SSLIOStream`, `.TCPServer`, and `.HTTPServer`) now accept either a
dictionary of options or an `ssl.SSLContext` object.
* 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``.
`tornado.autoreload`
~~~~~~~~~~~~~~~~~~~~
* `tornado.autoreload` is now more reliable when there are errors at import
time.
* Calling `tornado.autoreload.start` (or creating an `.Application` with
``debug=True``) twice on the same `.IOLoop` now does nothing (instead of
creating multiple periodic callbacks). Starting autoreload on
more than one `.IOLoop` in the same process now logs a warning.
* Scripts run by autoreload no longer inherit ``__future__`` imports
used by Tornado.
`tornado.auth`
~~~~~~~~~~~~~~
* On Python 3, the ``get_authenticated_user`` method family now returns
character strings instead of byte strings.
* Asynchronous methods defined in `tornado.auth` now return a
`.Future`, and their ``callback`` argument is optional. The
``Future`` interface is preferred as it offers better error handling
(the previous interface just logged a warning and returned None).
* The `tornado.auth` mixin classes now define a method
``get_auth_http_client``, which can be overridden to use a non-default
`.AsyncHTTPClient` instance (e.g. to use a different `.IOLoop`)
* Subclasses of `.OAuthMixin` are encouraged to override
`.OAuthMixin._oauth_get_user_future` instead of ``_oauth_get_user``,
although both methods are still supported.
`tornado.concurrent`
~~~~~~~~~~~~~~~~~~~~
* New module `tornado.concurrent` contains code to support working with
`concurrent.futures`, or to emulate future-based interface when that module
is not available.
``tornado.curl_httpclient``
~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Preliminary support for ``tornado.curl_httpclient`` on Python 3. The latest
official release of pycurl only supports Python 2, but Ubuntu has a
port available in 12.10 (``apt-get install python3-pycurl``). This port
currently has bugs that prevent it from handling arbitrary binary data
but it should work for textual (utf8) resources.
* Fix a crash with libcurl 7.29.0 if a curl object is created and closed
without being used.
`tornado.escape`
~~~~~~~~~~~~~~~~
* On Python 3, `~tornado.escape.json_encode` no longer accepts byte strings.
This mirrors the behavior of the underlying json module. Python 2 behavior
is unchanged but should be faster.
`tornado.gen`
~~~~~~~~~~~~~
* New decorator ``@gen.coroutine`` is available as an alternative to
``@gen.engine``. It automatically returns a
`.Future`, and within the function instead of
calling a callback you return a value with ``raise
gen.Return(value)`` (or simply ``return value`` in Python 3.3).
* Generators may now yield `.Future` objects.
* Callbacks produced by `.gen.Callback` and `.gen.Task` are now automatically
stack-context-wrapped, to minimize the risk of context leaks when used
with asynchronous functions that don't do their own wrapping.
* Fixed a memory leak involving generators, `.RequestHandler.flush`,
and clients closing connections while output is being written.
* Yielding a large list no longer has quadratic performance.
`tornado.httpclient`
~~~~~~~~~~~~~~~~~~~~
* `.AsyncHTTPClient.fetch` now returns a `.Future` and its callback argument
is optional. When the future interface is used, any error will be raised
automatically, as if `.HTTPResponse.rethrow` was called.
* `.AsyncHTTPClient.configure` and all `.AsyncHTTPClient` constructors
now take a ``defaults`` keyword argument. This argument should be a
dictionary, and its values will be used in place of corresponding
attributes of `~tornado.httpclient.HTTPRequest` that are not set.
* All unset attributes of `tornado.httpclient.HTTPRequest` are now
``None``. The default values of some attributes
(``connect_timeout``, ``request_timeout``, ``follow_redirects``,
``max_redirects``, ``use_gzip``, ``proxy_password``,
``allow_nonstandard_methods``, and ``validate_cert`` have been moved
from `~tornado.httpclient.HTTPRequest` to the client
implementations.
* 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.
* Secondary `.AsyncHTTPClient` callbacks (``streaming_callback``,
``header_callback``, and ``prepare_curl_callback``) now respect
`.StackContext`.
`tornado.httpserver`
~~~~~~~~~~~~~~~~~~~~
* `.HTTPServer` no longer logs an error when it is unable to read a second
request from an HTTP 1.1 keep-alive connection.
* `.HTTPServer` now takes a ``protocol`` keyword argument which can be set
to ``https`` if the server is behind an SSL-decoding proxy that does not
set any supported X-headers.
* `tornado.httpserver.HTTPConnection` now has a ``set_close_callback``
method that should be used instead of reaching into its ``stream``
attribute.
* Empty HTTP request arguments are no longer ignored. This applies to
``HTTPRequest.arguments`` and ``RequestHandler.get_argument[s]``
in WSGI and non-WSGI modes.
`tornado.ioloop`
~~~~~~~~~~~~~~~~
* 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).
* New method `.IOLoop.add_future` to run a callback on the IOLoop when
an asynchronous `.Future` finishes.
* `.IOLoop` now has a static `configure <.Configurable.configure>`
method like the one on `.AsyncHTTPClient`, which can be used to
select an `.IOLoop` implementation other than the default.
* 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.
* The `.IOLoop` constructor has a new keyword argument ``time_func``,
which can be used to set the time function used when scheduling callbacks.
This is most useful with the `time.monotonic` function, introduced
in Python 3.3 and backported to older versions via the ``monotime``
module. Using a monotonic clock here avoids problems when the system
clock is changed.
* New function `.IOLoop.time` returns the current time according to the
IOLoop. To use the new monotonic clock functionality, all calls to
`.IOLoop.add_timeout` must be either pass a `datetime.timedelta` or
a time relative to `.IOLoop.time`, not `time.time`. (`time.time` will
continue to work only as long as the IOLoop's ``time_func`` argument
is not used).
* New convenience method `.IOLoop.run_sync` can be used to start an IOLoop
just long enough to run a single coroutine.
* New method `.IOLoop.add_callback_from_signal` is safe to use in a signal
handler (the regular `.add_callback` method may deadlock).
* `.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.
* Method ``IOLoop.running()`` has been removed.
* `.IOLoop` has been refactored to better support subclassing.
* `.IOLoop.add_callback` and `.add_callback_from_signal` now take
``*args, **kwargs`` to pass along to the callback.
`tornado.iostream`
~~~~~~~~~~~~~~~~~~
* `.IOStream.connect` now has an optional ``server_hostname`` argument
which will be used for SSL certificate validation when applicable.
Additionally, when supported (on Python 3.2+), this hostname
will be sent via SNI (and this is supported by ``tornado.simple_httpclient``)
* Much of `.IOStream` has been refactored into a separate class
`.BaseIOStream`.
* New class `tornado.iostream.PipeIOStream` provides the IOStream
interface on pipe file descriptors.
* `.IOStream` now raises a new exception
``tornado.iostream.StreamClosedError`` when you attempt to read or
write after the stream has been closed (by either side).
* `.IOStream` now simply closes the connection when it gets an
``ECONNRESET`` error, rather than logging it as an error.
* ``IOStream.error`` no longer picks up unrelated exceptions.
* `.BaseIOStream.close` now has an ``exc_info`` argument (similar to the
one used in the `logging` module) that can be used to set the stream's
``error`` attribute when closing it.
* `.BaseIOStream.read_until_close` now works correctly when it is called
while there is buffered data.
* Fixed a major performance regression when run on PyPy (introduced in
Tornado 2.3).
`tornado.log`
~~~~~~~~~~~~~
* New module containing `.enable_pretty_logging` and `.LogFormatter`,
moved from the options module.
* `.LogFormatter` now handles non-ascii data in messages and tracebacks better.
`tornado.netutil`
~~~~~~~~~~~~~~~~~
* New class `tornado.netutil.Resolver` provides an asynchronous
interface to DNS resolution. The default implementation is still
blocking, but non-blocking implementations are available using one
of three optional dependencies: `~tornado.netutil.ThreadedResolver`
using the `concurrent.futures` thread pool,
`tornado.platform.caresresolver.CaresResolver` using the ``pycares``
library, or `tornado.platform.twisted.TwistedResolver` using ``twisted``
* New function `tornado.netutil.is_valid_ip` returns true if a given string
is a valid IP (v4 or v6) address.
* `tornado.netutil.bind_sockets` has a new ``flags`` argument that can
be used to pass additional flags to ``getaddrinfo``.
* `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` now works when Python was compiled
with ``--disable-ipv6`` but IPv6 DNS resolution is available on the
system.
* ``tornado.netutil.TCPServer`` has moved to its own module, `tornado.tcpserver`.
`tornado.options`
~~~~~~~~~~~~~~~~~
* 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.parse_config_file` now configures logging automatically
by default, in the same way that `~tornado.options.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.
* `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.options.parse_command_line` ``--help`` output now goes to ``stderr``
rather than ``stdout``.
* `tornado.options.options` is no longer a subclass of `dict`; attribute-style
access is now required.
* `tornado.options.options` (and `.OptionParser` instances generally) now
have a `.mockable()` method that returns a wrapper object compatible with
`mock.patch <unittest.mock.patch>`.
* Function ``tornado.options.enable_pretty_logging`` has been moved to the
`tornado.log` module.
`tornado.platform.caresresolver`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* New module containing an asynchronous implementation of the `.Resolver`
interface, using the ``pycares`` library.
`tornado.platform.twisted`
~~~~~~~~~~~~~~~~~~~~~~~~~~
* New class `tornado.platform.twisted.TwistedIOLoop` allows Tornado
code to be run on the Twisted reactor (as opposed to the existing
`.TornadoReactor`, which bridges the gap in the other direction).
* New class `tornado.platform.twisted.TwistedResolver` is an asynchronous
implementation of the `.Resolver` interface.
`tornado.process`
~~~~~~~~~~~~~~~~~
* New class `tornado.process.Subprocess` wraps `subprocess.Popen` with
`.PipeIOStream` access to the child's file descriptors.
``tornado.simple_httpclient``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* ``SimpleAsyncHTTPClient`` now takes a ``resolver`` keyword argument
(which may be passed to either the constructor or `configure
<.Configurable.configure>`), to allow it to use the new non-blocking
`tornado.netutil.Resolver`.
* When following redirects, ``SimpleAsyncHTTPClient`` now treats a 302
response code the same as a 303. This is contrary to the HTTP spec
but consistent with all browsers and other major HTTP clients
(including ``CurlAsyncHTTPClient``).
* The behavior of ``header_callback`` with ``SimpleAsyncHTTPClient`` has
changed and is now the same as that of ``CurlAsyncHTTPClient``. The
header callback now receives the first line of the response (e.g.
``HTTP/1.0 200 OK``) and the final empty line.
* ``tornado.simple_httpclient`` now accepts responses with a 304
status code that include a ``Content-Length`` header.
* Fixed a bug in which ``SimpleAsyncHTTPClient`` callbacks were being run in the
client's ``stack_context``.
`tornado.stack_context`
~~~~~~~~~~~~~~~~~~~~~~~
* `.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.
* Yield statements inside a ``with`` statement can cause stack
contexts to become inconsistent; an exception will now be raised
when this case is detected.
`tornado.template`
~~~~~~~~~~~~~~~~~~
* Errors while rendering templates no longer log the generated code,
since the enhanced stack traces (from version 2.1) should make this
unnecessary.
* The ``{% apply %}`` directive now works properly with functions that return
both unicode strings and byte strings (previously only byte strings were
supported).
* Code in templates is no longer affected by Tornado's ``__future__`` imports
(which previously included ``absolute_import`` and ``division``).
`tornado.testing`
~~~~~~~~~~~~~~~~~
* 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.
* New decorator `tornado.testing.gen_test` can be used to allow for
yielding `tornado.gen` objects in tests, as an alternative to the
``stop`` and ``wait`` methods of `.AsyncTestCase`.
* `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.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``.
* 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`.
* `.AsyncHTTPTestCase` no longer calls `.AsyncHTTPClient.close` for tests
that use the singleton `.IOLoop.instance`.
* `.LogTrapTestCase` no longer fails when run in unknown logging
configurations. This allows tests to be run under nose, which does its
own log buffering (`.LogTrapTestCase` doesn't do anything useful in this
case, but at least it doesn't break things any more).
``tornado.util``
~~~~~~~~~~~~~~~~
* ``tornado.util.b`` (which was only intended for internal use) is gone.
`tornado.web`
~~~~~~~~~~~~~
* `.RequestHandler.set_header` now overwrites previous header values
case-insensitively.
* `tornado.web.RequestHandler` has new attributes ``path_args`` and
``path_kwargs``, which contain the positional and keyword arguments
that are passed to the ``get``/``post``/etc method. These attributes
are set before those methods are called, so they are available during
``prepare()``
* `tornado.web.ErrorHandler` no longer requires XSRF tokens on ``POST``
requests, so posts to an unknown url will always return 404 instead of
complaining about XSRF tokens.
* 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.
* The ``Date`` HTTP header is now set by default on all responses.
* ``Etag``/``If-None-Match`` requests now work with `.StaticFileHandler`.
* `.StaticFileHandler` no longer sets ``Cache-Control: public`` unnecessarily.
* When gzip is enabled in a `tornado.web.Application`, appropriate
``Vary: Accept-Encoding`` headers are now sent.
* It is no longer necessary to pass all handlers for a host in a single
`.Application.add_handlers` call. Now the request will be matched
against the handlers for any ``host_pattern`` that includes the request's
``Host`` header.
`tornado.websocket`
~~~~~~~~~~~~~~~~~~~
* Client-side WebSocket support is now available:
`tornado.websocket.websocket_connect`
* `.WebSocketHandler` has new methods `~.WebSocketHandler.ping` and
`~.WebSocketHandler.on_pong` to send pings to the browser (not
supported on the ``draft76`` protocol)