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Try to avoid creating reference cycles involving generators. Only keep a

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reference to f_back when its really needed.  Do a little whitespace
normalization as well.  This whole file is a big war between tabs and spaces
but now is probably not the time to reindent everything.
This commit is contained in:
Neil Schemenauer 2001-06-21 02:41:10 +00:00
parent 2942131dac
commit 2b13ce8317
1 changed files with 27 additions and 14 deletions
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29
Python/ceval.c
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@ -138,6 +138,7 @@ gen_dealloc(genobject *gen)
static PyObject * static PyObject *
gen_iternext(genobject *gen) gen_iternext(genobject *gen)
{ {
PyThreadState *tstate = PyThreadState_GET();
PyFrameObject *f = gen->frame; PyFrameObject *f = gen->frame;
PyObject *result; PyObject *result;
@ -149,14 +150,23 @@ gen_iternext(genobject *gen)
if (f->f_stackbottom == NULL) { if (f->f_stackbottom == NULL) {
return NULL; return NULL;
} }
/* Generators always return to their most recent caller, not
* necessarily their creator. */
Py_INCREF(tstate->frame);
assert(f->f_back == NULL);
f->f_back = tstate->frame;
gen->running = 1; gen->running = 1;
result = eval_frame(f); result = eval_frame(f);
gen->running = 0; gen->running = 0;
/* The connection between this frame and its parent is over now, so
must NULL out f_back lest it get decref'ed when gen dies (note /* Don't keep the reference to f_back any longer than necessary. It
that eval_frame sets f->f_back without bumping its refcount: we * may keep a chain of frames alive or it could create a reference
never had a fully legit reference to it). */ * cycle. */
Py_DECREF(f->f_back);
f->f_back = NULL; f->f_back = NULL;
return result; return result;
} }
@ -568,9 +578,7 @@ eval_frame(PyFrameObject *f)
return NULL; return NULL;
} }
f->f_back = tstate->frame;
tstate->frame = f; tstate->frame = f;
co = f->f_code; co = f->f_code;
fastlocals = f->f_localsplus; fastlocals = f->f_localsplus;
freevars = f->f_localsplus + f->f_nlocals; freevars = f->f_localsplus + f->f_nlocals;
@ -2482,8 +2490,13 @@ eval_code2(PyCodeObject *co, PyObject *globals, PyObject *locals,
} }
if (co->co_flags & CO_GENERATOR) { if (co->co_flags & CO_GENERATOR) {
/* create a new generator that owns the ready to run frame /* Don't need to keep the reference to f_back, it will be set
* and return that as the value */ * when the generator is resumed. */
Py_DECREF(f->f_back);
f->f_back = NULL;
/* Create a new generator that owns the ready to run frame
* and return that as the value. */
return gen_new(f); return gen_new(f);
} }