The optimisation that allows a single check in the VM for either a pending
exception or non-empty scheduler queue doesn't work when threading is
enabled, as one thread can clear the sched_state if it has no pending
exception, meaning the thread with the pending exception will never see it.
This removes that optimisation for threaded builds.
Also fixes a race in non-scheduler builds where get-and-clear of the
pending exception is not protected by the atomic section.
Also removes the bulk of the inlining of pending exceptions and scheduler
handling from the VM. This just costs code size and complexity at no
performance benefit.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
If MICROPY_SCHEDULER_STATIC_NODES is enabled then C code can declare a
static mp_sched_node_t and schedule a callback using
mp_sched_schedule_node(). In contrast to using mp_sched_schedule(), the
node version will have at most one pending callback outstanding, and will
always be able to schedule if there is nothing already scheduled on this
node. This guarantees that the the callback will be called exactly once
after it is scheduled.
Signed-off-by: Damien George <damien@micropython.org>
This introduces a new macro to get the main thread and uses it to ensure
that asynchronous exceptions such as KeyboardInterrupt (CTRL+C) are only
scheduled on the main thread. This is more deterministic than being
scheduled on a random thread and is more in line with CPython that only
allow signal handlers to run on the main thread.
Fixes issue #7026.
Signed-off-by: David Lechner <david@pybricks.com>
This moves mp_pending_exception from mp_state_vm_t to mp_state_thread_t.
This allows exceptions to be scheduled on a specific thread.
Signed-off-by: David Lechner <david@pybricks.com>
This helper is added to properly set a pending exception, to mirror
mp_sched_schedule(), which schedules a function.
Signed-off-by: Damien George <damien@micropython.org>
Because the atomic section starts after checking whether the scheduler
state is pending, it's possible it can become a different state by the time
the atomic section starts.
This is especially likely on ports where MICROPY_BEGIN_ATOMIC_SECTION is
implemented with a mutex (i.e. it might block), but the race exists
regardless, i.e. if a context switch occurs between those two lines.
This is a more logical place to clear the KeyboardInterrupt traceback,
right before it is set as a pending exception. The clearing is also
optimised from a function call to a simple store of NULL.
Functions like mp_keyboard_interrupt() may need to be called from an IRQ
handler and may need to be in a special memory section, so provide a
generic wrapping macro for a port to do this. The macro name is chosen to
be MICROPY_WRAP_<function name in uppercase> so that (in the future with
more wrappers) each function could potentially be handled separately.
This function is tightly coupled to the state and behaviour of the
scheduler, and is a core part of the runtime: to schedule a pending
exception. So move it there.
Previous behaviour is when this argument is set to "true", in which case
the function will raise any pending exception. Setting it to "false" will
cancel any pending exception.
Behaviour was changed from stack to queue in
8977c7eb58, and this updates variable names
to match. Also updates other references (docs, error messages).
Jim Mussared
Damien George
David Lechner
Damien George
Andrew Leech