Skip to content

C
cpython
Commit 43411b56 authored by Neil Schemenauer's avatar Neil Schemenauer
Browse files
Options

Make more things internal to this file. Remove 

visit_finalizer_reachable since it's the same as visit_reachable.
Rename visit_reachable to visit_move.  Objects can now have the GC type
flag set, reachable by tp_traverse and not be in a GC linked list.  This
should make the collector more robust and easier to use by extension
module writers.  Add memory management functions for container objects
(new, del, resize).
parent cf22946c
Hide whitespace changes
Inline Side-by-side
Showing with 148 additions and 93 deletions
Modules/gcmodule.c
View file @ 43411b56
......@@ -8,7 +8,7 @@
Based on a post on the python-dev list. Ideas from Guido van Rossum,
Eric Tiedemann, and various others.
http://www.arctrix.com/nas/python/gc.html
http://www.arctrix.com/nas/python/gc/
http://www.python.org/pipermail/python-dev/2000-March/003869.html
http://www.python.org/pipermail/python-dev/2000-March/004010.html
http://www.python.org/pipermail/python-dev/2000-March/004022.html
......@@ -18,18 +18,21 @@
*/
#include "Python.h"
#ifdef WITH_CYCLE_GC
/* magic gc_refs value */
#define GC_MOVED -1
/* Get an object's GC head */
#define AS_GC(o) ((PyGC_Head *)(o)-1)
/* Get the object given the GC head */
#define FROM_GC(g) ((PyObject *)(((PyGC_Head *)g)+1))
/*** Global GC state ***/
/* linked lists of container objects */
static PyGC_Head generation0 = {&generation0, &generation0, 0};
PyGC_Head _PyGC_generation0 = {&_PyGC_generation0, &_PyGC_generation0, 0};
static PyGC_Head generation1 = {&generation1, &generation1, 0};
static PyGC_Head generation2 = {&generation2, &generation2, 0};
static int generation = 0; /* current generation being collected */
......@@ -43,6 +46,9 @@ static int threshold2 = 10; /* generation1 collections before collecting 2 */
/* net new objects allocated since last collection */
static int allocated;
/* true if we are currently running the collector */
static int collecting;
/* set for debugging information */
#define DEBUG_STATS (1<<0) /* print collection statistics */
#define DEBUG_COLLECTABLE (1<<1) /* print collectable objects */
......@@ -57,6 +63,9 @@ static int allocated;
DEBUG_SAVEALL
static int debug;
/* Special gc_refs value */
#define GC_MOVED -123
/* list of uncollectable objects */
static PyObject *garbage;
......@@ -86,10 +95,7 @@ gc_list_remove(PyGC_Head *node)
{
node->gc_prev->gc_next = node->gc_next;
node->gc_next->gc_prev = node->gc_prev;
#ifdef Py_DEBUG
node->gc_prev = NULL;
node->gc_next = NULL;
#endif
node->gc_next = NULL; /* object is not currently tracked */
}
static void
......@@ -137,13 +143,14 @@ gc_list_size(PyGC_Head *list)
/*** end of list stuff ***/
/* Set all gc_refs = ob_refcnt */
static void
update_refs(PyGC_Head *containers)
{
PyGC_Head *gc = containers->gc_next;
for (; gc != containers; gc=gc->gc_next) {
gc->gc_refs = PyObject_FROM_GC(gc)->ob_refcnt;
gc->gc_refs = FROM_GC(gc)->ob_refcnt;
}
}
......@@ -151,7 +158,9 @@ static int
visit_decref(PyObject *op, void *data)
{
if (op && PyObject_IS_GC(op)) {
PyObject_AS_GC(op)->gc_refs--;
PyGC_Head *gc = AS_GC(op);
if (gc->gc_next != NULL)
AS_GC(op)->gc_refs--;
}
return 0;
}
......@@ -163,8 +172,8 @@ subtract_refs(PyGC_Head *containers)
traverseproc traverse;
PyGC_Head *gc = containers->gc_next;
for (; gc != containers; gc=gc->gc_next) {
traverse = PyObject_FROM_GC(gc)->ob_type->tp_traverse;
(void) traverse(PyObject_FROM_GC(gc),
traverse = FROM_GC(gc)->ob_type->tp_traverse;
(void) traverse(FROM_GC(gc),
(visitproc)visit_decref,
NULL);
}
......@@ -188,13 +197,13 @@ move_roots(PyGC_Head *containers, PyGC_Head *roots)
}
static int
visit_reachable(PyObject *op, PyGC_Head *roots)
visit_move(PyObject *op, PyGC_Head *tolist)
{
if (PyObject_IS_GC(op)) {
PyGC_Head *gc = PyObject_AS_GC(op);
if (gc && gc->gc_refs != GC_MOVED) {
PyGC_Head *gc = AS_GC(op);
if (gc->gc_next != NULL && gc->gc_refs != GC_MOVED) {
gc_list_remove(gc);
gc_list_append(gc, roots);
gc_list_append(gc, tolist);
gc->gc_refs = GC_MOVED;
}
}
......@@ -209,15 +218,15 @@ move_root_reachable(PyGC_Head *reachable)
PyGC_Head *gc = reachable->gc_next;
for (; gc != reachable; gc=gc->gc_next) {
/* careful, reachable list is growing here */
PyObject *op = PyObject_FROM_GC(gc);
PyObject *op = FROM_GC(gc);
traverse = op->ob_type->tp_traverse;
(void) traverse(op,
(visitproc)visit_reachable,
(visitproc)visit_move,
(void *)reachable);
}
}
/* move all objects with finalizers (instances with __del__) */
/* Move all objects with finalizers (instances with __del__) */
static void
move_finalizers(PyGC_Head *unreachable, PyGC_Head *finalizers)
{
......@@ -230,7 +239,7 @@ move_finalizers(PyGC_Head *unreachable, PyGC_Head *finalizers)
Py_FatalError("PyGC: can't initialize __del__ string");
}
for (; gc != unreachable; gc=next) {
PyObject *op = PyObject_FROM_GC(gc);
PyObject *op = FROM_GC(gc);
next = gc->gc_next;
if (PyInstance_Check(op) && PyObject_HasAttr(op, delstr)) {
gc_list_remove(gc);
......@@ -239,22 +248,6 @@ move_finalizers(PyGC_Head *unreachable, PyGC_Head *finalizers)
}
}
/* called by tp_traverse */
static int
visit_finalizer_reachable(PyObject *op, PyGC_Head *finalizers)
{
if (PyObject_IS_GC(op)) {
PyGC_Head *gc = PyObject_AS_GC(op);
if (gc && gc->gc_refs != GC_MOVED) {
gc_list_remove(gc);
gc_list_append(gc, finalizers);
gc->gc_refs = GC_MOVED;
}
}
return 0;
}
/* Move objects referenced from roots to roots */
static void
move_finalizer_reachable(PyGC_Head *finalizers)
......@@ -263,9 +256,9 @@ move_finalizer_reachable(PyGC_Head *finalizers)
PyGC_Head *gc = finalizers->gc_next;
for (; gc != finalizers; gc=gc->gc_next) {
/* careful, finalizers list is growing here */
traverse = PyObject_FROM_GC(gc)->ob_type->tp_traverse;
(void) traverse(PyObject_FROM_GC(gc),
(visitproc)visit_finalizer_reachable,
traverse = FROM_GC(gc)->ob_type->tp_traverse;
(void) traverse(FROM_GC(gc),
(visitproc)visit_move,
(void *)finalizers);
}
}
......@@ -306,7 +299,7 @@ handle_finalizers(PyGC_Head *finalizers, PyGC_Head *old)
}
for (gc = finalizers->gc_next; gc != finalizers;
gc = finalizers->gc_next) {
PyObject *op = PyObject_FROM_GC(gc);
PyObject *op = FROM_GC(gc);
if ((debug & DEBUG_SAVEALL) || PyInstance_Check(op)) {
/* If SAVEALL is not set then just append
* instances to the list of garbage. We assume
......@@ -330,7 +323,7 @@ delete_garbage(PyGC_Head *unreachable, PyGC_Head *old)
while (unreachable->gc_next != unreachable) {
PyGC_Head *gc = unreachable->gc_next;
PyObject *op = PyObject_FROM_GC(gc);
PyObject *op = FROM_GC(gc);
if (debug & DEBUG_SAVEALL) {
PyList_Append(garbage, op);
}
......@@ -366,7 +359,7 @@ collect(PyGC_Head *young, PyGC_Head *old)
"gc: collecting generation %d...\n"
"gc: objects in each generation: %ld %ld %ld\n",
generation,
gc_list_size(&generation0),
gc_list_size(&_PyGC_generation0),
gc_list_size(&generation1),
gc_list_size(&generation2));
}
......@@ -407,7 +400,7 @@ collect(PyGC_Head *young, PyGC_Head *old)
gc = gc->gc_next) {
m++;
if (debug & DEBUG_COLLECTABLE) {
debug_cycle("collectable", PyObject_FROM_GC(gc));
debug_cycle("collectable", FROM_GC(gc));
}
}
/* call tp_clear on objects in the collectable set. This will cause
......@@ -421,7 +414,7 @@ collect(PyGC_Head *young, PyGC_Head *old)
gc = gc->gc_next) {
n++;
if (debug & DEBUG_UNCOLLECTABLE) {
debug_cycle("uncollectable", PyObject_FROM_GC(gc));
debug_cycle("uncollectable", FROM_GC(gc));
}
}
if (debug & DEBUG_STATS) {
......@@ -461,7 +454,7 @@ collect_generations(void)
if (collections1 > threshold2) {
generation = 2;
gc_list_merge(&generation0, &generation2);
gc_list_merge(&_PyGC_generation0, &generation2);
gc_list_merge(&generation1, &generation2);
if (generation2.gc_next != &generation2) {
n = collect(&generation2, &generation2);
......@@ -471,7 +464,7 @@ collect_generations(void)
else if (collections0 > threshold1) {
generation = 1;
collections1++;
gc_list_merge(&generation0, &generation1);
gc_list_merge(&_PyGC_generation0, &generation1);
if (generation1.gc_next != &generation1) {
n = collect(&generation1, &generation2);
}
......@@ -480,52 +473,13 @@ collect_generations(void)
else {
generation = 0;
collections0++;
if (generation0.gc_next != &generation0) {
n = collect(&generation0, &generation1);
if (_PyGC_generation0.gc_next != &_PyGC_generation0) {
n = collect(&_PyGC_generation0, &generation1);
}
}
return n;
}
void
_PyGC_Insert(PyObject *op)
{
/* collection lock since collecting may cause allocations */
static int collecting = 0;
#ifdef Py_DEBUG
if (!PyObject_IS_GC(op)) {
abort();
}
#endif
if (allocated > threshold0 &&
enabled &&
threshold0 &&
!collecting &&
!PyErr_Occurred()) {
collecting++;
collect_generations();
collecting--;
}
allocated++;
gc_list_append(PyObject_AS_GC(op), &generation0);
}
void
_PyGC_Remove(PyObject *op)
{
PyGC_Head *g = PyObject_AS_GC(op);
#ifdef Py_DEBUG
if (!PyObject_IS_GC(op)) {
abort();
}
#endif
gc_list_remove(g);
if (allocated > 0) {
allocated--;
}
}
static char gc_enable__doc__[] =
"enable() -> None\n"
"\n"
......@@ -595,7 +549,7 @@ gc_collect(PyObject *self, PyObject *args)
return NULL;
generation = 2;
gc_list_merge(&generation0, &generation2);
gc_list_merge(&_PyGC_generation0, &generation2);
gc_list_merge(&generation1, &generation2);
n = collect(&generation2, &generation2);
......@@ -693,7 +647,7 @@ gc_referents_for(PyObject *objs, PyGC_Head *list, PyObject *resultlist)
PyObject *obj;
traverseproc traverse;
for (gc = list->gc_next; gc != list; gc = gc->gc_next) {
obj = PyObject_FROM_GC(gc);
obj = FROM_GC(gc);
traverse = obj->ob_type->tp_traverse;
if (obj == objs || obj == resultlist)
continue;
......@@ -713,7 +667,7 @@ static PyObject *
gc_get_referents(PyObject *self, PyObject *args)
{
PyObject *result = PyList_New(0);
if (!(gc_referents_for(args, &generation0, result) &&
if (!(gc_referents_for(args, &_PyGC_generation0, result) &&
gc_referents_for(args, &generation1, result) &&
gc_referents_for(args, &generation2, result))) {
Py_DECREF(result);
......@@ -735,7 +689,7 @@ append_objects(PyObject *py_list, PyGC_Head *gc_list)
{
PyGC_Head *gc;
for (gc = gc_list->gc_next; gc != gc_list; gc = gc->gc_next) {
PyObject *op = PyObject_FROM_GC(gc);
PyObject *op = FROM_GC(gc);
if (op != py_list) {
Py_INCREF(op);
PyList_Append(py_list, op);
......@@ -751,7 +705,7 @@ gc_get_objects(PyObject *self, PyObject *args)
if (!PyArg_ParseTuple(args, ":get_objects")) /* check no args */
return NULL;
result = PyList_New(0);
append_objects(result, &generation0);
append_objects(result, &_PyGC_generation0);
append_objects(result, &generation1);
append_objects(result, &generation2);
return result;
......@@ -820,4 +774,105 @@ initgc(void)
PyInt_FromLong(DEBUG_LEAK));
}
/* for debugging */
void _PyGC_Dump(PyGC_Head *g)
{
_PyObject_Dump(FROM_GC(g));
}
#endif /* WITH_CYCLE_GC */
/* extension modules might be compiled with GC support so these
functions must always be available */
void
_PyObject_GC_Track(PyObject *op)
{
_PyObject_GC_TRACK(op);
}
void
_PyObject_GC_UnTrack(PyObject *op)
{
_PyObject_GC_UNTRACK(op);
}
PyObject *
_PyObject_GC_Malloc(PyTypeObject *tp, int size)
{
PyObject *op;
#ifdef WITH_CYCLE_GC
PyGC_Head *g = PyObject_MALLOC(_PyObject_VAR_SIZE(tp, size) +
sizeof(PyGC_Head));
if (g == NULL)
return (PyObject *)PyErr_NoMemory();
g->gc_next = NULL;
allocated++;
if (allocated > threshold0 &&
enabled &&
threshold0 &&
!collecting &&
!PyErr_Occurred()) {
collecting = 1;
collect_generations();
collecting = 0;
}
op = FROM_GC(g);
#else
op = PyObject_MALLOC(_PyObject_VAR_SIZE(tp, size));
if (op == NULL)
return (PyObject *)PyErr_NoMemory();
#endif
return op;
}
PyObject *
_PyObject_GC_New(PyTypeObject *tp)
{
PyObject *op = _PyObject_GC_Malloc(tp, 0);
return PyObject_INIT(op, tp);
}
PyVarObject *
_PyObject_GC_NewVar(PyTypeObject *tp, int size)
{
PyVarObject *op = (PyVarObject *) _PyObject_GC_Malloc(tp, size);
return PyObject_INIT_VAR(op, tp, size);
}
PyVarObject *
_PyObject_GC_Resize(PyVarObject *op, int size)
{
#ifdef WITH_CYCLE_GC
PyGC_Head *g = AS_GC(op);
g = PyObject_REALLOC(g, _PyObject_VAR_SIZE(op->ob_type, size) +
sizeof(PyGC_Head));
if (g == NULL)
return (PyVarObject *)PyErr_NoMemory();
op = (PyVarObject *) FROM_GC(g);
#else
op = PyObject_REALLOC(op, _PyObject_VAR_SIZE(op->ob_type, size));
if (op == NULL)
return (PyVarObject *)PyErr_NoMemory();
#endif
op->ob_size = size;
return op;
}
void
_PyObject_GC_Del(PyObject *op)
{
#ifdef WITH_CYCLE_GC
PyGC_Head *g = AS_GC(op);
if (g->gc_next != NULL)
gc_list_remove(g);
if (allocated > 0) {
allocated--;
}
PyObject_FREE(g);
#else
PyObject_FREE(op);
#endif
}
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7