https://www.python.org/dev/peps/pep-0475/
This implements something similar to PEP 475 on the unix port, and for the
VfsPosix class.
There are a few differences from the CPython implementation:
- Since we call mp_handle_pending() between any ENITR's, additional
functions could be called if MICROPY_ENABLE_SCHEDULER is enabled, not
just signal handlers.
- CPython only handles signal on the main thread, so other threads will
raise InterruptedError instead of retrying. On MicroPython,
mp_handle_pending() will currently raise exceptions on any thread.
A new macro MP_HAL_RETRY_SYSCALL is introduced to reduce duplicated code
and ensure that all instances behave the same. This will also allow other
ports that use POSIX-like system calls (and use, eg, VfsPosix) to provide
their own implementation if needed.
Addition of GIL EXIT/ENTER pairs are:
- modos: release the GIL during system calls. CPython does this as well.
- moduselect: release the GIL during the poll() syscall. This call can be
blocking, so it is important to allow other threads to run at this time.
- modusocket: release the GIL during system calls. Many of these calls can
be blocking, so it is important to allow other threads to run.
- unix_mphal: release the GIL during the read and write syscalls in
mp_hal_stdin_rx_chr and mp_hal_stdout_tx_strn. If we don't do this
threads are blocked when the REPL or the builtin input function are used.
- file, main, mpconfigport.h: release GIL during syscalls in built-in
functions that could block.
This mechanism will scale to to an arbitrary number of pollable objects, so
long as they implement the MP_STREAM_GET_FILENO ioctl. Since ussl objects
pass through ioctl requests transparently to the underlying socket object,
it will allow ussl sockets to be polled. And a user object with uio.IOBase
as a base could support polling.
This is to keep the top-level directory clean, to make it clear what is
core and what is a port, and to allow the repository to grow with new ports
in a sustainable way.
Jeff Epler
Jeff Epler
Scott Shawcroft
microDev
Jim Mussared
Diego Elio Pettenò
David Lechner
Damien George
Paul Sokolovsky