/
greenlet.c
2041 lines (1844 loc) · 59.9 KB
/
greenlet.c
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/* -*- indent-tabs-mode: nil; tab-width: 4; -*- */
/* Format with:
* clang-format -i --style=file src/greenlet/greenlet.c
*
*
* Fix missing braces with:
* clang-tidy src/greenlet/greenlet.c -fix -checks="readability-braces-around-statements"
*/
#define GREENLET_MODULE
#include "greenlet.h"
#include "structmember.h"
#ifdef __clang__
# pragma clang diagnostic push
# pragma clang diagnostic ignored "-Wunused-parameter"
# pragma clang diagnostic ignored "-Wmissing-field-initializers"
#endif
/***********************************************************
A PyGreenlet is a range of C stack addresses that must be
saved and restored in such a way that the full range of the
stack contains valid data when we switch to it.
Stack layout for a greenlet:
| ^^^ |
| older data |
| |
stack_stop . |_______________|
. | |
. | greenlet data |
. | in stack |
. * |_______________| . . _____________ stack_copy + stack_saved
. | | | |
. | data | |greenlet data|
. | unrelated | | saved |
. | to | | in heap |
stack_start . | this | . . |_____________| stack_copy
| greenlet |
| |
| newer data |
| vvv |
Note that a greenlet's stack data is typically partly at its correct
place in the stack, and partly saved away in the heap, but always in
the above configuration: two blocks, the more recent one in the heap
and the older one still in the stack (either block may be empty).
Greenlets are chained: each points to the previous greenlet, which is
the one that owns the data currently in the C stack above my
stack_stop. The currently running greenlet is the first element of
this chain. The main (initial) greenlet is the last one. Greenlets
whose stack is entirely in the heap can be skipped from the chain.
The chain is not related to execution order, but only to the order
in which bits of C stack happen to belong to greenlets at a particular
point in time.
The main greenlet doesn't have a stack_stop: it is responsible for the
complete rest of the C stack, and we don't know where it begins. We
use (char*) -1, the largest possible address.
States:
stack_stop == NULL && stack_start == NULL: did not start yet
stack_stop != NULL && stack_start == NULL: already finished
stack_stop != NULL && stack_start != NULL: active
The running greenlet's stack_start is undefined but not NULL.
***********************************************************/
/*** global state ***/
/* In the presence of multithreading, this is a bit tricky:
- ts_current always store a reference to a greenlet, but it is
not really the current greenlet after a thread switch occurred.
- each *running* greenlet uses its run_info field to know which
thread it is attached to. A greenlet can only run in the thread
where it was created. This run_info is a ref to tstate->dict.
- the thread state dict is used to save and restore ts_current,
using the dictionary key 'ts_curkey'.
*/
extern PyTypeObject PyGreenlet_Type;
#if PY_VERSION_HEX >= 0x030700A3
# define GREENLET_PY37 1
#else
# define GREENLET_PY37 0
#endif
#if PY_VERSION_HEX >= 0x30A00B1
/*
Python 3.10 beta 1 changed tstate->use_tracing to a nested cframe member.
See https://github.com/python/cpython/pull/25276
We have to save and restore this as well.
*/
#define TSTATE_USE_TRACING(tstate) (tstate->cframe->use_tracing)
#define GREENLET_USE_CFRAME 1
#else
#define TSTATE_USE_TRACING(tstate) (tstate->use_tracing)
#define GREENLET_USE_CFRAME 0
#endif
#ifndef Py_SET_REFCNT
/* Py_REFCNT and Py_SIZE macros are converted to functions
https://bugs.python.org/issue39573 */
# define Py_SET_REFCNT(obj, refcnt) Py_REFCNT(obj) = (refcnt)
#endif
#ifndef _Py_DEC_REFTOTAL
/* _Py_DEC_REFTOTAL macro has been removed from Python 3.9 by:
https://github.com/python/cpython/commit/49932fec62c616ec88da52642339d83ae719e924
*/
# ifdef Py_REF_DEBUG
# define _Py_DEC_REFTOTAL _Py_RefTotal--
# else
# define _Py_DEC_REFTOTAL
# endif
#endif
/* Weak reference to the switching-to greenlet during the slp switch */
static PyGreenlet* volatile ts_target = NULL;
/* Strong reference to the switching from greenlet after the switch */
static PyGreenlet* volatile ts_origin = NULL;
/* Strong reference to the current greenlet in this thread state */
static PyGreenlet* volatile ts_current = NULL;
/* NULL if error, otherwise args tuple to pass around during slp switch */
static PyObject* volatile ts_passaround_args = NULL;
static PyObject* volatile ts_passaround_kwargs = NULL;
/***********************************************************/
/* Thread-aware routines, switching global variables when needed */
#define STATE_OK \
(ts_current->run_info == PyThreadState_GET()->dict || \
!green_updatecurrent())
static PyObject* ts_curkey;
static PyObject* ts_delkey;
static PyObject* ts_tracekey;
static PyObject* ts_event_switch;
static PyObject* ts_event_throw;
static PyObject* PyExc_GreenletError;
static PyObject* PyExc_GreenletExit;
static PyObject* ts_empty_tuple;
static PyObject* ts_empty_dict;
#define GREENLET_GC_FLAGS Py_TPFLAGS_HAVE_GC
#define GREENLET_tp_alloc PyType_GenericAlloc
#define GREENLET_tp_free PyObject_GC_Del
#define GREENLET_tp_traverse green_traverse
#define GREENLET_tp_clear green_clear
#define GREENLET_tp_is_gc green_is_gc
static void
green_clear_exc(PyGreenlet* g)
{
#if GREENLET_PY37
g->exc_info = NULL;
g->exc_state.exc_type = NULL;
g->exc_state.exc_value = NULL;
g->exc_state.exc_traceback = NULL;
g->exc_state.previous_item = NULL;
#else
g->exc_type = NULL;
g->exc_value = NULL;
g->exc_traceback = NULL;
#endif
}
static PyGreenlet*
green_create_main(void)
{
PyGreenlet* gmain;
PyObject* dict = PyThreadState_GetDict();
if (dict == NULL) {
if (!PyErr_Occurred()) {
PyErr_NoMemory();
}
return NULL;
}
/* create the main greenlet for this thread */
gmain = (PyGreenlet*)PyType_GenericAlloc(&PyGreenlet_Type, 0);
if (gmain == NULL) {
return NULL;
}
gmain->stack_start = (char*)1;
gmain->stack_stop = (char*)-1;
gmain->run_info = dict;
Py_INCREF(dict);
return gmain;
}
static int
green_updatecurrent(void)
{
PyObject *exc, *val, *tb;
PyThreadState* tstate;
PyGreenlet* current;
PyGreenlet* previous;
PyObject* deleteme;
green_updatecurrent_restart:
/* save current exception */
PyErr_Fetch(&exc, &val, &tb);
/* get ts_current from the active tstate */
tstate = PyThreadState_GET();
if (tstate->dict &&
(current = (PyGreenlet*)PyDict_GetItem(tstate->dict, ts_curkey))) {
/* found -- remove it, to avoid keeping a ref */
Py_INCREF(current);
PyDict_DelItem(tstate->dict, ts_curkey);
}
else {
/* first time we see this tstate */
current = green_create_main();
if (current == NULL) {
Py_XDECREF(exc);
Py_XDECREF(val);
Py_XDECREF(tb);
return -1;
}
}
assert(current->run_info == tstate->dict);
green_updatecurrent_retry:
/* update ts_current as soon as possible, in case of nested switches */
Py_INCREF(current);
previous = ts_current;
ts_current = current;
/* save ts_current as the current greenlet of its own thread */
if (PyDict_SetItem(previous->run_info, ts_curkey, (PyObject*)previous)) {
Py_DECREF(previous);
Py_DECREF(current);
Py_XDECREF(exc);
Py_XDECREF(val);
Py_XDECREF(tb);
return -1;
}
Py_DECREF(previous);
/* green_dealloc() cannot delete greenlets from other threads, so
it stores them in the thread dict; delete them now. */
deleteme = PyDict_GetItem(tstate->dict, ts_delkey);
if (deleteme != NULL) {
/* The only reference to these greenlets should be in this list, so
clearing the list should let them be deleted again, triggering
calls to green_dealloc() in the correct thread. This may run
arbitrary Python code?
*/
PyList_SetSlice(deleteme, 0, INT_MAX, NULL);
}
if (ts_current != current) {
/* some Python code executed above and there was a thread switch,
* so ts_current points to some other thread again. We need to
* delete ts_curkey (it's likely there) and retry. */
PyDict_DelItem(tstate->dict, ts_curkey);
goto green_updatecurrent_retry;
}
/* release an extra reference */
Py_DECREF(current);
/* restore current exception */
PyErr_Restore(exc, val, tb);
/* thread switch could happen during PyErr_Restore, in that
case there's nothing to do except restart from scratch. */
if (ts_current->run_info != tstate->dict) {
goto green_updatecurrent_restart;
}
return 0;
}
static PyObject*
green_statedict(PyGreenlet* g)
{
while (!PyGreenlet_STARTED(g)) {
g = g->parent;
if (g == NULL) {
/* garbage collected greenlet in chain */
return NULL;
}
}
return g->run_info;
}
/***********************************************************/
/* Some functions must not be inlined:
* slp_restore_state, when inlined into slp_switch might cause
it to restore stack over its own local variables
* slp_save_state, when inlined would add its own local
variables to the saved stack, wasting space
* slp_switch, cannot be inlined for obvious reasons
* g_initialstub, when inlined would receive a pointer into its
own stack frame, leading to incomplete stack save/restore
*/
#if defined(__GNUC__) && \
(__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
# define GREENLET_NOINLINE_SUPPORTED
# define GREENLET_NOINLINE(name) __attribute__((noinline)) name
#elif defined(_MSC_VER) && (_MSC_VER >= 1300)
# define GREENLET_NOINLINE_SUPPORTED
# define GREENLET_NOINLINE(name) __declspec(noinline) name
#endif
#ifdef GREENLET_NOINLINE_SUPPORTED
/* add forward declarations */
static void GREENLET_NOINLINE(slp_restore_state)(void);
static int GREENLET_NOINLINE(slp_save_state)(char*);
# if !(defined(MS_WIN64) && defined(_M_X64))
static int GREENLET_NOINLINE(slp_switch)(void);
# endif
static int GREENLET_NOINLINE(g_initialstub)(void*);
# define GREENLET_NOINLINE_INIT() \
do { \
} while (0)
#else
/* force compiler to call functions via pointers */
static void (*slp_restore_state)(void);
static int (*slp_save_state)(char*);
static int (*slp_switch)(void);
static int (*g_initialstub)(void*);
# define GREENLET_NOINLINE(name) cannot_inline_##name
# define GREENLET_NOINLINE_INIT() \
do { \
slp_restore_state = GREENLET_NOINLINE(slp_restore_state); \
slp_save_state = GREENLET_NOINLINE(slp_save_state); \
slp_switch = GREENLET_NOINLINE(slp_switch); \
g_initialstub = GREENLET_NOINLINE(g_initialstub); \
} while (0)
#endif
/*
* the following macros are spliced into the OS/compiler
* specific code, in order to simplify maintenance.
*/
#define SLP_SAVE_STATE(stackref, stsizediff) \
stackref += STACK_MAGIC; \
if (slp_save_state((char*)stackref)) \
return -1; \
if (!PyGreenlet_ACTIVE(ts_target)) \
return 1; \
stsizediff = ts_target->stack_start - (char*)stackref
#define SLP_RESTORE_STATE() slp_restore_state()
#define SLP_EVAL
#define slp_switch GREENLET_NOINLINE(slp_switch)
#include "slp_platformselect.h"
#undef slp_switch
#ifndef STACK_MAGIC
# error \
"greenlet needs to be ported to this platform, or taught how to detect your compiler properly."
#endif /* !STACK_MAGIC */
#ifdef EXTERNAL_ASM
/* CCP addition: Make these functions, to be called from assembler.
* The token include file for the given platform should enable the
* EXTERNAL_ASM define so that this is included.
*/
intptr_t
slp_save_state_asm(intptr_t* ref)
{
intptr_t diff;
SLP_SAVE_STATE(ref, diff);
return diff;
}
void
slp_restore_state_asm(void)
{
SLP_RESTORE_STATE();
}
extern int
slp_switch(void);
#endif
/***********************************************************/
static int
g_save(PyGreenlet* g, char* stop)
{
/* Save more of g's stack into the heap -- at least up to 'stop'
g->stack_stop |________|
| |
| __ stop . . . . .
| | ==> . .
|________| _______
| | | |
| | | |
g->stack_start | | |_______| g->stack_copy
*/
intptr_t sz1 = g->stack_saved;
intptr_t sz2 = stop - g->stack_start;
assert(g->stack_start != NULL);
if (sz2 > sz1) {
char* c = (char*)PyMem_Realloc(g->stack_copy, sz2);
if (!c) {
PyErr_NoMemory();
return -1;
}
memcpy(c + sz1, g->stack_start + sz1, sz2 - sz1);
g->stack_copy = c;
g->stack_saved = sz2;
}
return 0;
}
static void GREENLET_NOINLINE(slp_restore_state)(void)
{
PyGreenlet* g = ts_target;
PyGreenlet* owner = ts_current;
#ifdef SLP_BEFORE_RESTORE_STATE
SLP_BEFORE_RESTORE_STATE();
#endif
/* Restore the heap copy back into the C stack */
if (g->stack_saved != 0) {
memcpy(g->stack_start, g->stack_copy, g->stack_saved);
PyMem_Free(g->stack_copy);
g->stack_copy = NULL;
g->stack_saved = 0;
}
if (owner->stack_start == NULL) {
owner = owner->stack_prev; /* greenlet is dying, skip it */
}
while (owner && owner->stack_stop <= g->stack_stop) {
owner = owner->stack_prev; /* find greenlet with more stack */
}
g->stack_prev = owner;
}
static int GREENLET_NOINLINE(slp_save_state)(char* stackref)
{
/* must free all the C stack up to target_stop */
char* target_stop = ts_target->stack_stop;
PyGreenlet* owner = ts_current;
assert(owner->stack_saved == 0);
if (owner->stack_start == NULL) {
owner = owner->stack_prev; /* not saved if dying */
}
else {
owner->stack_start = stackref;
}
#ifdef SLP_BEFORE_SAVE_STATE
SLP_BEFORE_SAVE_STATE();
#endif
while (owner->stack_stop < target_stop) {
/* ts_current is entierely within the area to free */
if (g_save(owner, owner->stack_stop)) {
return -1; /* XXX */
}
owner = owner->stack_prev;
}
if (owner != ts_target) {
if (g_save(owner, target_stop)) {
return -1; /* XXX */
}
}
return 0;
}
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;
#if GREENLET_PY37
current->context = tstate->context;
#endif
#if GREENLET_PY37
current->exc_info = tstate->exc_info;
current->exc_state = tstate->exc_state;
#else
current->exc_type = tstate->exc_type;
current->exc_value = tstate->exc_value;
current->exc_traceback = tstate->exc_traceback;
#endif
#if GREENLET_USE_CFRAME
current->cframe = tstate->cframe;
#endif
}
err = slp_switch();
if (err < 0) { /* error */
PyGreenlet* current = ts_current;
current->top_frame = NULL;
#if GREENLET_PY37
green_clear_exc(current);
#else
current->exc_type = NULL;
current->exc_value = NULL;
current->exc_traceback = NULL;
#endif
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;
#if GREENLET_PY37
tstate->context = target->context;
target->context = NULL;
/* Incrementing this value invalidates the contextvars cache,
which would otherwise remain valid across switches */
tstate->context_ver++;
#endif
#if GREENLET_PY37
tstate->exc_state = target->exc_state;
tstate->exc_info =
target->exc_info ? target->exc_info : &tstate->exc_state;
#else
tstate->exc_type = target->exc_type;
tstate->exc_value = target->exc_value;
tstate->exc_traceback = target->exc_traceback;
#endif
green_clear_exc(target);
#if GREENLET_USE_CFRAME
tstate->cframe = target->cframe;
#endif
assert(ts_origin == NULL);
Py_INCREF(target);
ts_current = target;
ts_origin = origin;
ts_target = NULL;
}
return err;
}
static int
g_calltrace(PyObject* tracefunc, PyObject* event, PyGreenlet* origin,
PyGreenlet* target)
{
PyObject* retval;
PyObject *exc_type, *exc_val, *exc_tb;
PyThreadState* tstate;
PyErr_Fetch(&exc_type, &exc_val, &exc_tb);
tstate = PyThreadState_GET();
tstate->tracing++;
TSTATE_USE_TRACING(tstate) = 0;
retval = PyObject_CallFunction(tracefunc, "O(OO)", event, origin, target);
tstate->tracing--;
TSTATE_USE_TRACING(tstate) =
(tstate->tracing <= 0 &&
((tstate->c_tracefunc != NULL) || (tstate->c_profilefunc != NULL)));
if (retval == NULL) {
/* In case of exceptions trace function is removed */
if (PyDict_GetItem(tstate->dict, ts_tracekey)) {
PyDict_DelItem(tstate->dict, ts_tracekey);
}
Py_XDECREF(exc_type);
Py_XDECREF(exc_val);
Py_XDECREF(exc_tb);
return -1;
}
else {
Py_DECREF(retval);
}
PyErr_Restore(exc_type, exc_val, exc_tb);
return 0;
}
static PyObject*
g_switch(PyGreenlet* target, PyObject* args, PyObject* kwargs)
{
/* _consumes_ a reference to the args tuple and kwargs dict,
and return a new tuple reference */
int err = 0;
PyObject* run_info;
/* check ts_current */
if (!STATE_OK) {
Py_XDECREF(args);
Py_XDECREF(kwargs);
return NULL;
}
run_info = green_statedict(target);
if (run_info == NULL || run_info != ts_current->run_info) {
Py_XDECREF(args);
Py_XDECREF(kwargs);
PyErr_SetString(PyExc_GreenletError,
run_info ?
"cannot switch to a different thread" :
"cannot switch to a garbage collected greenlet");
return NULL;
}
ts_passaround_args = args;
ts_passaround_kwargs = kwargs;
/* find the real target by ignoring dead greenlets,
and if necessary starting a greenlet. */
while (target) {
if (PyGreenlet_ACTIVE(target)) {
ts_target = target;
err = g_switchstack();
break;
}
if (!PyGreenlet_STARTED(target)) {
void* dummymarker;
ts_target = target;
err = g_initialstub(&dummymarker);
if (err == 1) {
continue; /* retry the switch */
}
break;
}
target = target->parent;
}
/* For a very short time, immediately after the 'atomic'
g_switchstack() call, global variables are in a known state.
We need to save everything we need, before it is destroyed
by calls into arbitrary Python code. */
args = ts_passaround_args;
ts_passaround_args = NULL;
kwargs = ts_passaround_kwargs;
ts_passaround_kwargs = NULL;
if (err < 0) {
/* Turn switch errors into switch throws */
assert(ts_origin == NULL);
Py_CLEAR(kwargs);
Py_CLEAR(args);
}
else {
PyGreenlet* origin;
PyGreenlet* current;
PyObject* tracefunc;
origin = ts_origin;
ts_origin = NULL;
current = ts_current;
if ((tracefunc = PyDict_GetItem(current->run_info, ts_tracekey)) !=
NULL) {
Py_INCREF(tracefunc);
if (g_calltrace(tracefunc,
args ? ts_event_switch : ts_event_throw,
origin,
current) < 0) {
/* Turn trace errors into switch throws */
Py_CLEAR(kwargs);
Py_CLEAR(args);
}
Py_DECREF(tracefunc);
}
Py_DECREF(origin);
}
/* We need to figure out what values to pass to the target greenlet
based on the arguments that have been passed to greenlet.switch(). If
switch() was just passed an arg tuple, then we'll just return that.
If only keyword arguments were passed, then we'll pass the keyword
argument dict. Otherwise, we'll create a tuple of (args, kwargs) and
return both. */
if (kwargs == NULL) {
return args;
}
else if (PyDict_Size(kwargs) == 0) {
Py_DECREF(kwargs);
return args;
}
else if (PySequence_Length(args) == 0) {
Py_DECREF(args);
return kwargs;
}
else {
PyObject* tuple = PyTuple_New(2);
if (tuple == NULL) {
Py_DECREF(args);
Py_DECREF(kwargs);
return NULL;
}
PyTuple_SET_ITEM(tuple, 0, args);
PyTuple_SET_ITEM(tuple, 1, kwargs);
return tuple;
}
}
static PyObject*
g_handle_exit(PyObject* result)
{
if (result == NULL && PyErr_ExceptionMatches(PyExc_GreenletExit)) {
/* catch and ignore GreenletExit */
PyObject *exc, *val, *tb;
PyErr_Fetch(&exc, &val, &tb);
if (val == NULL) {
Py_INCREF(Py_None);
val = Py_None;
}
result = val;
Py_DECREF(exc);
Py_XDECREF(tb);
}
if (result != NULL) {
/* package the result into a 1-tuple */
PyObject* r = result;
result = PyTuple_New(1);
if (result) {
PyTuple_SET_ITEM(result, 0, r);
}
else {
Py_DECREF(r);
}
}
return result;
}
static int GREENLET_NOINLINE(g_initialstub)(void* mark)
{
int err;
PyObject *o, *run;
PyObject *exc, *val, *tb;
PyObject* run_info;
PyGreenlet* self = ts_target;
PyObject* args = ts_passaround_args;
PyObject* kwargs = ts_passaround_kwargs;
/* save exception in case getattr clears it */
PyErr_Fetch(&exc, &val, &tb);
/* self.run is the object to call in the new greenlet */
run = PyObject_GetAttrString((PyObject*)self, "run");
if (run == NULL) {
Py_XDECREF(exc);
Py_XDECREF(val);
Py_XDECREF(tb);
return -1;
}
/* restore saved exception */
PyErr_Restore(exc, val, tb);
/* recheck the state in case getattr caused thread switches */
if (!STATE_OK) {
Py_DECREF(run);
return -1;
}
/* recheck run_info in case greenlet reparented anywhere above */
run_info = green_statedict(self);
if (run_info == NULL || run_info != ts_current->run_info) {
Py_DECREF(run);
PyErr_SetString(PyExc_GreenletError,
run_info ?
"cannot switch to a different thread" :
"cannot switch to a garbage collected greenlet");
return -1;
}
/* by the time we got here another start could happen elsewhere,
* that means it should now be a regular switch
*/
if (PyGreenlet_STARTED(self)) {
Py_DECREF(run);
ts_passaround_args = args;
ts_passaround_kwargs = kwargs;
return 1;
}
/* start the greenlet */
self->stack_start = NULL;
self->stack_stop = (char*)mark;
if (ts_current->stack_start == NULL) {
/* ts_current is dying */
self->stack_prev = ts_current->stack_prev;
}
else {
self->stack_prev = ts_current;
}
self->top_frame = NULL;
green_clear_exc(self);
self->recursion_depth = PyThreadState_GET()->recursion_depth;
/* restore arguments in case they are clobbered */
ts_target = self;
ts_passaround_args = args;
ts_passaround_kwargs = kwargs;
/* perform the initial switch */
err = g_switchstack();
/* returns twice!
The 1st time with err=1: we are in the new greenlet
The 2nd time with err=0: back in the caller's greenlet
*/
if (err == 1) {
/* in the new greenlet */
PyGreenlet* origin;
PyObject* tracefunc;
PyObject* result;
PyGreenlet* parent;
self->stack_start = (char*)1; /* running */
/* grab origin while we still can */
origin = ts_origin;
ts_origin = NULL;
/* now use run_info to store the statedict */
o = self->run_info;
self->run_info = green_statedict(self->parent);
Py_INCREF(self->run_info);
Py_XDECREF(o);
if ((tracefunc = PyDict_GetItem(self->run_info, ts_tracekey)) !=
NULL) {
Py_INCREF(tracefunc);
if (g_calltrace(tracefunc,
args ? ts_event_switch : ts_event_throw,
origin,
self) < 0) {
/* Turn trace errors into switch throws */
Py_CLEAR(kwargs);
Py_CLEAR(args);
}
Py_DECREF(tracefunc);
}
Py_DECREF(origin);
if (args == NULL) {
/* pending exception */
result = NULL;
}
else {
/* call g.run(*args, **kwargs) */
result = PyObject_Call(run, args, kwargs);
Py_DECREF(args);
Py_XDECREF(kwargs);
}
Py_DECREF(run);
result = g_handle_exit(result);
/* jump back to parent */
self->stack_start = NULL; /* dead */
for (parent = self->parent; parent != NULL; parent = parent->parent) {
result = g_switch(parent, result, NULL);
/* Return here means switch to parent failed,
* in which case we throw *current* exception
* to the next parent in chain.
*/
assert(result == NULL);
}
/* We ran out of parents, cannot continue */
PyErr_WriteUnraisable((PyObject*)self);
Py_FatalError("greenlets cannot continue");
}
/* back in the parent */
if (err < 0) {
/* start failed badly, restore greenlet state */
self->stack_start = NULL;
self->stack_stop = NULL;
self->stack_prev = NULL;
}
return err;
}
/***********************************************************/
static PyObject*
green_new(PyTypeObject* type, PyObject* args, PyObject* kwds)
{
PyObject* o =
PyBaseObject_Type.tp_new(type, ts_empty_tuple, ts_empty_dict);
if (o != NULL) {
if (!STATE_OK) {
Py_DECREF(o);
return NULL;
}
Py_INCREF(ts_current);
((PyGreenlet*)o)->parent = ts_current;
#if GREENLET_USE_CFRAME
((PyGreenlet*)o)->cframe = &PyThreadState_GET()->root_cframe;
#endif
}
return o;
}
static int
green_setrun(PyGreenlet* self, PyObject* nrun, void* c);
static int
green_setparent(PyGreenlet* self, PyObject* nparent, void* c);
static int
green_init(PyGreenlet* self, PyObject* args, PyObject* kwargs)
{
PyObject* run = NULL;
PyObject* nparent = NULL;
static char* kwlist[] = {"run", "parent", 0};
if (!PyArg_ParseTupleAndKeywords(
args, kwargs, "|OO:green", kwlist, &run, &nparent)) {
return -1;
}
if (run != NULL) {
if (green_setrun(self, run, NULL)) {
return -1;
}
}
if (nparent != NULL && nparent != Py_None) {
return green_setparent(self, nparent, NULL);
}
return 0;
}
static int
kill_greenlet(PyGreenlet* self)
{
/* Cannot raise an exception to kill the greenlet if
it is not running in the same thread! */
if (self->run_info == PyThreadState_GET()->dict) {
/* The dying greenlet cannot be a parent of ts_current
because the 'parent' field chain would hold a
reference */
PyObject* result;
PyGreenlet* oldparent;
PyGreenlet* tmp;
if (!STATE_OK) {
return -1;
}
oldparent = self->parent;
self->parent = ts_current;
Py_INCREF(self->parent);
/* Send the greenlet a GreenletExit exception. */
PyErr_SetNone(PyExc_GreenletExit);
result = g_switch(self, NULL, NULL);
tmp = self->parent;
self->parent = oldparent;
Py_XDECREF(tmp);
if (result == NULL) {
return -1;
}
Py_DECREF(result);
return 0;
}
else {
/* Not the same thread! Temporarily save the greenlet
into its thread's ts_delkey list. */
PyObject* lst;
lst = PyDict_GetItem(self->run_info, ts_delkey);
if (lst == NULL) {
lst = PyList_New(0);
if (lst == NULL
|| PyDict_SetItem(self->run_info, ts_delkey, lst) < 0) {
return -1;
}
/* PyDict_SetItem now holds a strong reference. PyList_New also
returned a fresh reference. We need to DECREF it now and let
the dictionary keep sole ownership. Frow now on, we're working