py/objgenerator: Allow pend_throw to an unstarted generator.

Replace the is_running field with a tri-state variable to indicate
running/not-running/pending-exception.

Update tests to cover the various cases.

This allows cancellation in uasyncio even if the coroutine hasn't been
executed yet.  Fixes #5242
This commit is contained in:
Jim Mussared 2019-10-29 21:04:55 +11:00 committed by Damien George
parent 576ed89224
commit 5578182ec9
3 changed files with 113 additions and 27 deletions

View File

@ -43,7 +43,10 @@ const mp_obj_exception_t mp_const_GeneratorExit_obj = {{&mp_type_GeneratorExit},
typedef struct _mp_obj_gen_instance_t {
mp_obj_base_t base;
bool is_running;
// mp_const_none: Not-running, no exception.
// MP_OBJ_NULL: Running, no exception.
// other: Not running, pending exception.
mp_obj_t pend_exc;
mp_code_state_t code_state;
} mp_obj_gen_instance_t;
@ -60,7 +63,7 @@ STATIC mp_obj_t gen_wrap_call(mp_obj_t self_in, size_t n_args, size_t n_kw, cons
n_state * sizeof(mp_obj_t) + n_exc_stack * sizeof(mp_exc_stack_t));
o->base.type = &mp_type_gen_instance;
o->is_running = false;
o->pend_exc = mp_const_none;
o->code_state.fun_bc = self_fun;
o->code_state.ip = 0;
o->code_state.n_state = n_state;
@ -105,7 +108,7 @@ STATIC mp_obj_t native_gen_wrap_call(mp_obj_t self_in, size_t n_args, size_t n_k
o->base.type = &mp_type_gen_instance;
// Parse the input arguments and set up the code state
o->is_running = false;
o->pend_exc = mp_const_none;
o->code_state.fun_bc = self_fun;
o->code_state.ip = (const byte*)prelude_offset;
o->code_state.n_state = n_state;
@ -151,28 +154,30 @@ mp_vm_return_kind_t mp_obj_gen_resume(mp_obj_t self_in, mp_obj_t send_value, mp_
*ret_val = MP_OBJ_STOP_ITERATION;
return MP_VM_RETURN_NORMAL;
}
// Ensure the generator cannot be reentered during execution
if (self->pend_exc == MP_OBJ_NULL) {
mp_raise_ValueError("generator already executing");
}
#if MICROPY_PY_GENERATOR_PEND_THROW
// If exception is pending (set using .pend_throw()), process it now.
if (self->pend_exc != mp_const_none) {
throw_value = self->pend_exc;
}
#endif
// If the generator is started, allow sending a value.
if (self->code_state.sp == self->code_state.state - 1) {
if (send_value != mp_const_none) {
mp_raise_TypeError("can't send non-None value to a just-started generator");
}
} else {
#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;
}
*self->code_state.sp = send_value;
}
// Ensure the generator cannot be reentered during execution
if (self->is_running) {
mp_raise_ValueError("generator already executing");
}
self->is_running = true;
// Mark as running
self->pend_exc = MP_OBJ_NULL;
// Set up the correct globals context for the generator and execute it
self->code_state.old_globals = mp_globals_get();
@ -195,7 +200,8 @@ mp_vm_return_kind_t mp_obj_gen_resume(mp_obj_t self_in, mp_obj_t send_value, mp_
mp_globals_set(self->code_state.old_globals);
self->is_running = false;
// Mark as not running
self->pend_exc = mp_const_none;
switch (ret_kind) {
case MP_VM_RETURN_NORMAL:
@ -313,11 +319,11 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(gen_instance_close_obj, gen_instance_close);
#if MICROPY_PY_GENERATOR_PEND_THROW
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");
if (self->pend_exc == MP_OBJ_NULL) {
mp_raise_ValueError("generator already executing");
}
mp_obj_t prev = *self->code_state.sp;
*self->code_state.sp = exc_in;
mp_obj_t prev = self->pend_exc;
self->pend_exc = exc_in;
return prev;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(gen_instance_pend_throw_obj, gen_instance_pend_throw);

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@ -13,6 +13,7 @@ except AttributeError:
raise SystemExit
# Verify that an injected exception will be raised from next().
print(next(g))
print(next(g))
g.pend_throw(ValueError())
@ -25,7 +26,76 @@ except Exception as e:
print("ret was:", v)
# Verify that pend_throw works on an unstarted coroutine.
g = gen()
g.pend_throw(OSError())
try:
gen().pend_throw(ValueError())
except TypeError:
print("TypeError")
next(g)
except Exception as e:
print("raised", repr(e))
# Verify that you can't resume the coroutine from within the running coroutine.
def gen_next():
next(g)
yield 1
g = gen_next()
try:
next(g)
except Exception as e:
print("raised", repr(e))
# Verify that you can't pend_throw from within the running coroutine.
def gen_pend_throw():
g.pend_throw(ValueError())
yield 1
g = gen_pend_throw()
try:
next(g)
except Exception as e:
print("raised", repr(e))
# Verify that the pend_throw exception can be ignored.
class CancelledError(Exception):
pass
def gen_cancelled():
for i in range(5):
try:
yield i
except CancelledError:
print('ignore CancelledError')
g = gen_cancelled()
print(next(g))
g.pend_throw(CancelledError())
print(next(g))
# ...but not if the generator hasn't started.
g = gen_cancelled()
g.pend_throw(CancelledError())
try:
next(g)
except Exception as e:
print("raised", repr(e))
# Verify that calling pend_throw returns the previous exception.
g = gen()
next(g)
print(repr(g.pend_throw(CancelledError())))
print(repr(g.pend_throw(OSError)))
# Verify that you can pend_throw(None) to cancel a previous pend_throw.
g = gen()
next(g)
g.pend_throw(CancelledError())
print(repr(g.pend_throw(None)))
print(next(g))

View File

@ -2,4 +2,14 @@
1
raised ValueError()
ret was: None
TypeError
raised OSError()
raised ValueError('generator already executing',)
raised ValueError('generator already executing',)
0
ignore CancelledError
1
raised CancelledError()
None
CancelledError()
CancelledError()
1