From 63644016669c173190c71d39fb33ad9502fe2b0f Mon Sep 17 00:00:00 2001 From: Paul Sokolovsky Date: Sat, 21 Oct 2017 12:13:44 +0300 Subject: [PATCH] py/objgenerator: Allow to pend an exception for next execution. This implements .pend_throw(exc) method, which sets up an exception to be triggered on the next call to generator's .__next__() or .send() method. This is unlike .throw(), which immediately starts to execute the generator to process the exception. This effectively adds Future-like capabilities to generator protocol (exception will be raised in the future). The need for such a method arised to implement uasyncio wait_for() function efficiently (its behavior is clearly "Future" like, and normally would require to introduce an expensive Future wrapper around all native couroutines, like upstream asyncio does). py/objgenerator: pend_throw: Return previous pended value. This effectively allows to store an additional value (not necessary an exception) in a coroutine while it's not being executed. uasyncio has exactly this usecase: to mark a coro waiting in I/O queue (and thus not executed in the normal scheduling queue), for the purpose of implementing wait_for() function (cancellation of such waiting coro by a timeout). --- py/mpconfig.h | 9 +++++++ py/objgenerator.c | 30 ++++++++++++++++++++++-- tests/basics/generator_pend_throw.py | 26 ++++++++++++++++++++ tests/basics/generator_pend_throw.py.exp | 4 ++++ tests/run-tests | 2 +- 5 files changed, 68 insertions(+), 3 deletions(-) create mode 100644 tests/basics/generator_pend_throw.py create mode 100644 tests/basics/generator_pend_throw.py.exp diff --git a/py/mpconfig.h b/py/mpconfig.h index 19bae4f88..763bb378e 100644 --- a/py/mpconfig.h +++ b/py/mpconfig.h @@ -706,6 +706,15 @@ typedef double mp_float_t; #define MICROPY_PY_ASYNC_AWAIT (1) #endif +// Non-standard .pend_throw() method for generators, allowing for +// Future-like behavior with respect to exception handling: an +// exception set with .pend_throw() will activate on the next call +// to generator's .send() or .__next__(). (This is useful to implement +// async schedulers.) +#ifndef MICROPY_PY_GENERATOR_PEND_THROW +#define MICROPY_PY_GENERATOR_PEND_THROW (1) +#endif + // Issue a warning when comparing str and bytes objects #ifndef MICROPY_PY_STR_BYTES_CMP_WARN #define MICROPY_PY_STR_BYTES_CMP_WARN (0) diff --git a/py/objgenerator.c b/py/objgenerator.c index 9a294debb..8c1260b60 100644 --- a/py/objgenerator.c +++ b/py/objgenerator.c @@ -4,7 +4,7 @@ * The MIT License (MIT) * * Copyright (c) 2013, 2014 Damien P. George - * Copyright (c) 2014 Paul Sokolovsky + * Copyright (c) 2014-2017 Paul Sokolovsky * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal @@ -104,7 +104,16 @@ mp_vm_return_kind_t mp_obj_gen_resume(mp_obj_t self_in, mp_obj_t send_value, mp_ mp_raise_TypeError("can't send non-None value to a just-started generator"); } } else { - *self->code_state.sp = send_value; + #if MICROPY_PY_GENERATOR_PEND_THROW + // If exception is pending (set using .pend_throw()), process it now. + if (*self->code_state.sp != mp_const_none) { + throw_value = *self->code_state.sp; + *self->code_state.sp = MP_OBJ_NULL; + } else + #endif + { + *self->code_state.sp = send_value; + } } mp_obj_dict_t *old_globals = mp_globals_get(); mp_globals_set(self->globals); @@ -125,6 +134,9 @@ mp_vm_return_kind_t mp_obj_gen_resume(mp_obj_t self_in, mp_obj_t send_value, mp_ case MP_VM_RETURN_YIELD: *ret_val = *self->code_state.sp; + #if MICROPY_PY_GENERATOR_PEND_THROW + *self->code_state.sp = mp_const_none; + #endif break; case MP_VM_RETURN_EXCEPTION: { @@ -219,10 +231,24 @@ STATIC mp_obj_t gen_instance_close(mp_obj_t self_in) { STATIC MP_DEFINE_CONST_FUN_OBJ_1(gen_instance_close_obj, gen_instance_close); +STATIC mp_obj_t gen_instance_pend_throw(mp_obj_t self_in, mp_obj_t exc_in) { + mp_obj_gen_instance_t *self = MP_OBJ_TO_PTR(self_in); + if (self->code_state.sp == self->code_state.state - 1) { + mp_raise_TypeError("can't pend throw to just-started generator"); + } + mp_obj_t prev = *self->code_state.sp; + *self->code_state.sp = exc_in; + return prev; +} +STATIC MP_DEFINE_CONST_FUN_OBJ_2(gen_instance_pend_throw_obj, gen_instance_pend_throw); + STATIC const mp_rom_map_elem_t gen_instance_locals_dict_table[] = { { MP_ROM_QSTR(MP_QSTR_close), MP_ROM_PTR(&gen_instance_close_obj) }, { MP_ROM_QSTR(MP_QSTR_send), MP_ROM_PTR(&gen_instance_send_obj) }, { MP_ROM_QSTR(MP_QSTR_throw), MP_ROM_PTR(&gen_instance_throw_obj) }, + #if MICROPY_PY_GENERATOR_PEND_THROW + { MP_ROM_QSTR(MP_QSTR_pend_throw), MP_ROM_PTR(&gen_instance_pend_throw_obj) }, + #endif }; STATIC MP_DEFINE_CONST_DICT(gen_instance_locals_dict, gen_instance_locals_dict_table); diff --git a/tests/basics/generator_pend_throw.py b/tests/basics/generator_pend_throw.py new file mode 100644 index 000000000..949655612 --- /dev/null +++ b/tests/basics/generator_pend_throw.py @@ -0,0 +1,26 @@ +def gen(): + i = 0 + while 1: + yield i + i += 1 + +g = gen() + +try: + g.pend_throw +except AttributeError: + print("SKIP") + raise SystemExit + + +print(next(g)) +print(next(g)) +g.pend_throw(ValueError()) + +v = None +try: + v = next(g) +except Exception as e: + print("raised", repr(e)) + +print("ret was:", v) diff --git a/tests/basics/generator_pend_throw.py.exp b/tests/basics/generator_pend_throw.py.exp new file mode 100644 index 000000000..f9894a089 --- /dev/null +++ b/tests/basics/generator_pend_throw.py.exp @@ -0,0 +1,4 @@ +0 +1 +raised ValueError() +ret was: None diff --git a/tests/run-tests b/tests/run-tests index 45cb1a746..8719befbd 100755 --- a/tests/run-tests +++ b/tests/run-tests @@ -337,7 +337,7 @@ def run_tests(pyb, tests, args, base_path="."): # Some tests are known to fail with native emitter # Remove them from the below when they work if args.emit == 'native': - skip_tests.update({'basics/%s.py' % t for t in 'gen_yield_from gen_yield_from_close gen_yield_from_ducktype gen_yield_from_exc gen_yield_from_iter gen_yield_from_send gen_yield_from_stopped gen_yield_from_throw gen_yield_from_throw2 gen_yield_from_throw3 generator1 generator2 generator_args generator_close generator_closure generator_exc generator_return generator_send'.split()}) # require yield + skip_tests.update({'basics/%s.py' % t for t in 'gen_yield_from gen_yield_from_close gen_yield_from_ducktype gen_yield_from_exc gen_yield_from_iter gen_yield_from_send gen_yield_from_stopped gen_yield_from_throw gen_yield_from_throw2 gen_yield_from_throw3 generator1 generator2 generator_args generator_close generator_closure generator_exc generator_pend_throw generator_return generator_send'.split()}) # require yield skip_tests.update({'basics/%s.py' % t for t in 'bytes_gen class_store_class globals_del string_join'.split()}) # require yield skip_tests.update({'basics/async_%s.py' % t for t in 'def await await2 for for2 with with2'.split()}) # require yield skip_tests.update({'basics/%s.py' % t for t in 'try_reraise try_reraise2'.split()}) # require raise_varargs