static int g_switchstack(void)
{
/* perform a stack switch according to some global variables
that must be set before:
- ts_current: current greenlet (holds a reference)
- ts_target: greenlet to switch to
- ts_passaround_args: NULL if PyErr_Occurred(),
else a tuple of args sent to ts_target (holds a reference)
- ts_passaround_kwargs: same as ts_passaround_args
*/
int err = slp_switch();
if (err < 0)
{
/* error */
}
else
{
greenlet* target = ts_target;
greenlet* origin = ts_current;
ts_current = target;
}
return err;
}
STATIC_NOINLINE
void *_stacklet_switchstack(void *(*save_state)(void*, void*),
void *(*restore_state)(void*, void*),
void *extra)
{
return slp_switch(save_state, restore_state, extra);
}
static int g_switchstack(void)
{
/* perform a stack switch according to some global variables
that must be set before:
- ts_current: current greenlet (holds a reference)
- ts_target: greenlet to switch to
- ts_passaround_args: NULL if PyErr_Occurred(),
else a tuple of args sent to ts_target (holds a reference)
- ts_passaround_kwargs: same as ts_passaround_args
*/
int err;
{ /* save state */
PyGreenlet* current = ts_current;
PyThreadState* tstate = PyThreadState_GET();
current->recursion_depth = tstate->recursion_depth;
current->top_frame = tstate->frame;
current->exc_type = tstate->exc_type;
current->exc_value = tstate->exc_value;
current->exc_traceback = tstate->exc_traceback;
}
err = slp_switch();
if (err < 0) { /* error */
PyGreenlet* current = ts_current;
current->top_frame = NULL;
current->exc_type = NULL;
current->exc_value = NULL;
current->exc_traceback = NULL;
}
else {
PyObject* args = ts_passaround_args;
PyObject* kwargs = ts_passaround_kwargs;
PyGreenlet* target = ts_target;
PyGreenlet* origin = ts_current;
PyThreadState* tstate = PyThreadState_GET();
tstate->recursion_depth = target->recursion_depth;
tstate->frame = target->top_frame;
target->top_frame = NULL;
tstate->exc_type = target->exc_type;
target->exc_type = NULL;
tstate->exc_value = target->exc_value;
target->exc_value = NULL;
tstate->exc_traceback = target->exc_traceback;
target->exc_traceback = NULL;
ts_current = target;
Py_INCREF(target);
Py_DECREF(origin);
ts_passaround_args = args;
ts_passaround_kwargs = kwargs;
}
return err;
}
int
slp_transfer(PyCStackObject **cstprev, PyCStackObject *cst,
PyTaskletObject *prev)
{
PyThreadState *ts = PyThreadState_GET();
/* since we change the stack we must assure that the protocol was met */
STACKLESS_ASSERT();
if ((intptr_t *) &ts > ts->st.cstack_base)
return climb_stack_and_transfer(cstprev, cst, prev);
if (cst == NULL || cst->ob_size == 0)
cst = ts->st.initial_stub;
if (cst != NULL) {
if (cst->tstate != ts) {
PyErr_SetString(PyExc_SystemError,
"bad thread state in transfer");
return -1;
}
if (ts->st.cstack_base != cst->startaddr) {
PyErr_SetString(PyExc_SystemError,
"bad stack reference in transfer");
return -1;
}
/* record the context of the target stack */
ts->st.serial_last_jump = cst->serial;
/*
* if stacks are same and refcount==1, it must be the same
* task. In this case, we would destroy the target before
* switching. Therefore, we simply don't switch, just save.
*/
if (cstprev && *cstprev == cst && cst->ob_refcnt == 1)
cst = NULL;
}
_cstprev = cstprev;
_cst = cst;
_prev = prev;
return slp_switch();
}
static int g_switchstack(void)
{
/* Perform a stack switch according to some global variables
that must be set before:
- ts_current: current greenlet (holds a reference)
- ts_target: greenlet to switch to (weak reference)
- ts_passaround_args: NULL if PyErr_Occurred(),
else a tuple of args sent to ts_target (holds a reference)
- ts_passaround_kwargs: switch kwargs (holds a reference)
On return results are passed via global variables as well:
- ts_origin: originating greenlet (holds a reference)
- ts_current: current greenlet (holds a reference)
- ts_passaround_args: NULL if PyErr_Occurred(),
else a tuple of args sent to ts_current (holds a reference)
- ts_passaround_kwargs: switch kwargs (holds a reference)
It is very important that stack switch is 'atomic', i.e. no
calls into other Python code allowed (except very few that
are safe), because global variables are very fragile.
*/
int err;
{ /* save state */
PyGreenlet* current = ts_current;
PyThreadState* tstate = PyThreadState_GET();
current->recursion_depth = tstate->recursion_depth;
current->top_frame = tstate->frame;
current->exc_type = tstate->exc_type;
current->exc_value = tstate->exc_value;
current->exc_traceback = tstate->exc_traceback;
}
err = slp_switch();
if (err < 0) { /* error */
PyGreenlet* current = ts_current;
current->top_frame = NULL;
current->exc_type = NULL;
current->exc_value = NULL;
current->exc_traceback = NULL;
assert(ts_origin == NULL);
ts_target = NULL;
}
else {
PyGreenlet* target = ts_target;
PyGreenlet* origin = ts_current;
PyThreadState* tstate = PyThreadState_GET();
tstate->recursion_depth = target->recursion_depth;
tstate->frame = target->top_frame;
target->top_frame = NULL;
tstate->exc_type = target->exc_type;
target->exc_type = NULL;
tstate->exc_value = target->exc_value;
target->exc_value = NULL;
tstate->exc_traceback = target->exc_traceback;
target->exc_traceback = NULL;
assert(ts_origin == NULL);
Py_INCREF(target);
ts_current = target;
ts_origin = origin;
ts_target = NULL;
}
return err;
}
