The main aim of this change is to reduce the number of heap allocations
when writing data to a stream. This is done in two ways:
1. Eliminate appending of data when .write() is called multiple times
before calling .drain(). With this commit, the data is written out
immediately if the underlying stream is not blocked, so there is no
accumulation of the data in a temporary buffer.
2. Eliminate copying of non-bytes objects passed to .write(). Prior to
this commit, passing a bytearray or memoryview to .write() would always
result in a copy of it being made and turned into a bytes object. That
won't happen now if the underlying stream is not blocked.
Also, this change makes .write () more closely implement the CPython
documented semantics: "The method attempts to write the data to the
underlying socket immediately. If that fails, the data is queued in an
internal write buffer until it can be sent."
Currently when using uasyncio.start_server() the socket configuration is
done inside a uasyncio.create_task() background function. If the address
and port are already in use however this throws an OSError which cannot be
cleanly caught behind the create_task().
This commit moves the getaddrinfo and socket binding to the start_server()
function, and only creates the task if that succeeds. This means that any
OSError from the initial socket configuration is propagated directly up the
call stack, compatible with CPython behaviour.
See #7444.
Signed-off-by: Damien George <damien@micropython.org>
With docs and a multi-test using TCP server/client.
This method is a MicroPython extension, although there is discussion of
adding it to CPython: https://bugs.python.org/issue41305
Signed-off-by: Mike Teachman <mike.teachman@gmail.com>
This fix prevents server.wait_closed() from raising an AttributeError when
trying to access server.task. This can happen if it is called immediately
after start_server().
It raises on EOFError instead of an IncompleteReadError (which is what
CPython does). But the latter is derived from EOFError so code compatible
with MicroPython and CPython can be written by catching EOFError (eg see
included test).
Fixes issue #6156.
Signed-off-by: Damien George <damien@micropython.org>
This commit adds a completely new implementation of the uasyncio module.
The aim of this version (compared to the original one in micropython-lib)
is to be more compatible with CPython's asyncio module, so that one can
more easily write code that runs under both MicroPython and CPython (and
reuse CPython asyncio libraries, follow CPython asyncio tutorials, etc).
Async code is not easy to write and any knowledge users already have from
CPython asyncio should transfer to uasyncio without effort, and vice versa.
The implementation here attempts to provide good compatibility with
CPython's asyncio while still being "micro" enough to run where MicroPython
runs. This follows the general philosophy of MicroPython itself, to make it
feel like Python.
The main change is to use a Task object for each coroutine. This allows
more flexibility to queue tasks in various places, eg the main run loop,
tasks waiting on events, locks or other tasks. It no longer requires
pre-allocating a fixed queue size for the main run loop.
A pairing heap is used to queue Tasks.
It's currently implemented in pure Python, separated into components with
lazy importing for optional components. In the future parts of this
implementation can be moved to C to improve speed and reduce memory usage.
But the aim is to maintain a pure-Python version as a reference version.
