| /* |
| |
| Reference Cycle Garbage Collection |
| ================================== |
| |
| Neil Schemenauer <nas@arctrix.com> |
| |
| 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/ |
| 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 |
| |
| For a highlevel view of the collection process, read the collect |
| function. |
| |
| */ |
| |
| #include "Python.h" |
| |
| /* 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 ***/ |
| |
| struct gc_generation { |
| PyGC_Head head; |
| int threshold; /* collection threshold */ |
| int count; /* count of allocations or collections of younger |
| generations */ |
| }; |
| |
| #define NUM_GENERATIONS 3 |
| #define GEN_HEAD(n) (&generations[n].head) |
| |
| /* linked lists of container objects */ |
| static struct gc_generation generations[NUM_GENERATIONS] = { |
| /* PyGC_Head, threshold, count */ |
| {{{GEN_HEAD(0), GEN_HEAD(0), 0}}, 700, 0}, |
| {{{GEN_HEAD(1), GEN_HEAD(1), 0}}, 10, 0}, |
| {{{GEN_HEAD(2), GEN_HEAD(2), 0}}, 10, 0}, |
| }; |
| |
| PyGC_Head *_PyGC_generation0 = GEN_HEAD(0); |
| |
| static int enabled = 1; /* automatic collection enabled? */ |
| |
| /* true if we are currently running the collector */ |
| static int collecting = 0; |
| |
| /* list of uncollectable objects */ |
| static PyObject *garbage = NULL; |
| |
| /* Python string to use if unhandled exception occurs */ |
| static PyObject *gc_str = NULL; |
| |
| /* Python string used to look for __del__ attribute. */ |
| static PyObject *delstr = NULL; |
| |
| /* set for debugging information */ |
| #define DEBUG_STATS (1<<0) /* print collection statistics */ |
| #define DEBUG_COLLECTABLE (1<<1) /* print collectable objects */ |
| #define DEBUG_UNCOLLECTABLE (1<<2) /* print uncollectable objects */ |
| #define DEBUG_OBJECTS (1<<4) /* print other objects */ |
| #define DEBUG_SAVEALL (1<<5) /* save all garbage in gc.garbage */ |
| #define DEBUG_LEAK DEBUG_COLLECTABLE | \ |
| DEBUG_UNCOLLECTABLE | \ |
| DEBUG_OBJECTS | \ |
| DEBUG_SAVEALL |
| static int debug; |
| static PyObject *tmod = NULL; |
| |
| /*-------------------------------------------------------------------------- |
| gc_refs values. |
| |
| Between collections, every gc'ed object has one of two gc_refs values: |
| |
| GC_UNTRACKED |
| The initial state; objects returned by PyObject_GC_Malloc are in this |
| state. The object doesn't live in any generation list, and its |
| tp_traverse slot must not be called. |
| |
| GC_REACHABLE |
| The object lives in some generation list, and its tp_traverse is safe to |
| call. An object transitions to GC_REACHABLE when PyObject_GC_Track |
| is called. |
| |
| During a collection, gc_refs can temporarily take on other states: |
| |
| >= 0 |
| At the start of a collection, update_refs() copies the true refcount |
| to gc_refs, for each object in the generation being collected. |
| subtract_refs() then adjusts gc_refs so that it equals the number of |
| times an object is referenced directly from outside the generation |
| being collected. |
| gc_refs remains >= 0 throughout these steps. |
| |
| GC_TENTATIVELY_UNREACHABLE |
| move_unreachable() then moves objects not reachable (whether directly or |
| indirectly) from outside the generation into an "unreachable" set. |
| Objects that are found to be reachable have gc_refs set to GC_REACHABLE |
| again. Objects that are found to be unreachable have gc_refs set to |
| GC_TENTATIVELY_UNREACHABLE. It's "tentatively" because the pass doing |
| this can't be sure until it ends, and GC_TENTATIVELY_UNREACHABLE may |
| transition back to GC_REACHABLE. |
| |
| Only objects with GC_TENTATIVELY_UNREACHABLE still set are candidates |
| for collection. If it's decided not to collect such an object (e.g., |
| it has a __del__ method), its gc_refs is restored to GC_REACHABLE again. |
| ---------------------------------------------------------------------------- |
| */ |
| #define GC_UNTRACKED _PyGC_REFS_UNTRACKED |
| #define GC_REACHABLE _PyGC_REFS_REACHABLE |
| #define GC_TENTATIVELY_UNREACHABLE _PyGC_REFS_TENTATIVELY_UNREACHABLE |
| |
| #define IS_TRACKED(o) ((AS_GC(o))->gc.gc_refs != GC_UNTRACKED) |
| #define IS_REACHABLE(o) ((AS_GC(o))->gc.gc_refs == GC_REACHABLE) |
| #define IS_TENTATIVELY_UNREACHABLE(o) ( \ |
| (AS_GC(o))->gc.gc_refs == GC_TENTATIVELY_UNREACHABLE) |
| |
| /*** list functions ***/ |
| |
| static void |
| gc_list_init(PyGC_Head *list) |
| { |
| list->gc.gc_prev = list; |
| list->gc.gc_next = list; |
| } |
| |
| static int |
| gc_list_is_empty(PyGC_Head *list) |
| { |
| return (list->gc.gc_next == list); |
| } |
| |
| #if 0 |
| /* This became unused after gc_list_move() was introduced. */ |
| /* Append `node` to `list`. */ |
| static void |
| gc_list_append(PyGC_Head *node, PyGC_Head *list) |
| { |
| node->gc.gc_next = list; |
| node->gc.gc_prev = list->gc.gc_prev; |
| node->gc.gc_prev->gc.gc_next = node; |
| list->gc.gc_prev = node; |
| } |
| #endif |
| |
| /* Remove `node` from the gc list it's currently in. */ |
| static void |
| gc_list_remove(PyGC_Head *node) |
| { |
| node->gc.gc_prev->gc.gc_next = node->gc.gc_next; |
| node->gc.gc_next->gc.gc_prev = node->gc.gc_prev; |
| node->gc.gc_next = NULL; /* object is not currently tracked */ |
| } |
| |
| /* Move `node` from the gc list it's currently in (which is not explicitly |
| * named here) to the end of `list`. This is semantically the same as |
| * gc_list_remove(node) followed by gc_list_append(node, list). |
| */ |
| static void |
| gc_list_move(PyGC_Head *node, PyGC_Head *list) |
| { |
| PyGC_Head *new_prev; |
| PyGC_Head *current_prev = node->gc.gc_prev; |
| PyGC_Head *current_next = node->gc.gc_next; |
| /* Unlink from current list. */ |
| current_prev->gc.gc_next = current_next; |
| current_next->gc.gc_prev = current_prev; |
| /* Relink at end of new list. */ |
| new_prev = node->gc.gc_prev = list->gc.gc_prev; |
| new_prev->gc.gc_next = list->gc.gc_prev = node; |
| node->gc.gc_next = list; |
| } |
| |
| /* append list `from` onto list `to`; `from` becomes an empty list */ |
| static void |
| gc_list_merge(PyGC_Head *from, PyGC_Head *to) |
| { |
| PyGC_Head *tail; |
| assert(from != to); |
| if (!gc_list_is_empty(from)) { |
| tail = to->gc.gc_prev; |
| tail->gc.gc_next = from->gc.gc_next; |
| tail->gc.gc_next->gc.gc_prev = tail; |
| to->gc.gc_prev = from->gc.gc_prev; |
| to->gc.gc_prev->gc.gc_next = to; |
| } |
| gc_list_init(from); |
| } |
| |
| static Py_ssize_t |
| gc_list_size(PyGC_Head *list) |
| { |
| PyGC_Head *gc; |
| Py_ssize_t n = 0; |
| for (gc = list->gc.gc_next; gc != list; gc = gc->gc.gc_next) { |
| n++; |
| } |
| return n; |
| } |
| |
| /* Append objects in a GC list to a Python list. |
| * Return 0 if all OK, < 0 if error (out of memory for list). |
| */ |
| static int |
| append_objects(PyObject *py_list, PyGC_Head *gc_list) |
| { |
| PyGC_Head *gc; |
| for (gc = gc_list->gc.gc_next; gc != gc_list; gc = gc->gc.gc_next) { |
| PyObject *op = FROM_GC(gc); |
| if (op != py_list) { |
| if (PyList_Append(py_list, op)) { |
| return -1; /* exception */ |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /*** end of list stuff ***/ |
| |
| |
| /* Set all gc_refs = ob_refcnt. After this, gc_refs is > 0 for all objects |
| * in containers, and is GC_REACHABLE for all tracked gc objects not in |
| * containers. |
| */ |
| static void |
| update_refs(PyGC_Head *containers) |
| { |
| PyGC_Head *gc = containers->gc.gc_next; |
| for (; gc != containers; gc = gc->gc.gc_next) { |
| assert(gc->gc.gc_refs == GC_REACHABLE); |
| gc->gc.gc_refs = FROM_GC(gc)->ob_refcnt; |
| /* Python's cyclic gc should never see an incoming refcount |
| * of 0: if something decref'ed to 0, it should have been |
| * deallocated immediately at that time. |
| * Possible cause (if the assert triggers): a tp_dealloc |
| * routine left a gc-aware object tracked during its teardown |
| * phase, and did something-- or allowed something to happen -- |
| * that called back into Python. gc can trigger then, and may |
| * see the still-tracked dying object. Before this assert |
| * was added, such mistakes went on to allow gc to try to |
| * delete the object again. In a debug build, that caused |
| * a mysterious segfault, when _Py_ForgetReference tried |
| * to remove the object from the doubly-linked list of all |
| * objects a second time. In a release build, an actual |
| * double deallocation occurred, which leads to corruption |
| * of the allocator's internal bookkeeping pointers. That's |
| * so serious that maybe this should be a release-build |
| * check instead of an assert? |
| */ |
| assert(gc->gc.gc_refs != 0); |
| } |
| } |
| |
| /* A traversal callback for subtract_refs. */ |
| static int |
| visit_decref(PyObject *op, void *data) |
| { |
| assert(op != NULL); |
| if (PyObject_IS_GC(op)) { |
| PyGC_Head *gc = AS_GC(op); |
| /* We're only interested in gc_refs for objects in the |
| * generation being collected, which can be recognized |
| * because only they have positive gc_refs. |
| */ |
| assert(gc->gc.gc_refs != 0); /* else refcount was too small */ |
| if (gc->gc.gc_refs > 0) |
| gc->gc.gc_refs--; |
| } |
| return 0; |
| } |
| |
| /* Subtract internal references from gc_refs. After this, gc_refs is >= 0 |
| * for all objects in containers, and is GC_REACHABLE for all tracked gc |
| * objects not in containers. The ones with gc_refs > 0 are directly |
| * reachable from outside containers, and so can't be collected. |
| */ |
| static void |
| subtract_refs(PyGC_Head *containers) |
| { |
| traverseproc traverse; |
| PyGC_Head *gc = containers->gc.gc_next; |
| for (; gc != containers; gc=gc->gc.gc_next) { |
| traverse = FROM_GC(gc)->ob_type->tp_traverse; |
| (void) traverse(FROM_GC(gc), |
| (visitproc)visit_decref, |
| NULL); |
| } |
| } |
| |
| /* A traversal callback for move_unreachable. */ |
| static int |
| visit_reachable(PyObject *op, PyGC_Head *reachable) |
| { |
| if (PyObject_IS_GC(op)) { |
| PyGC_Head *gc = AS_GC(op); |
| const Py_ssize_t gc_refs = gc->gc.gc_refs; |
| |
| if (gc_refs == 0) { |
| /* This is in move_unreachable's 'young' list, but |
| * the traversal hasn't yet gotten to it. All |
| * we need to do is tell move_unreachable that it's |
| * reachable. |
| */ |
| gc->gc.gc_refs = 1; |
| } |
| else if (gc_refs == GC_TENTATIVELY_UNREACHABLE) { |
| /* This had gc_refs = 0 when move_unreachable got |
| * to it, but turns out it's reachable after all. |
| * Move it back to move_unreachable's 'young' list, |
| * and move_unreachable will eventually get to it |
| * again. |
| */ |
| gc_list_move(gc, reachable); |
| gc->gc.gc_refs = 1; |
| } |
| /* Else there's nothing to do. |
| * If gc_refs > 0, it must be in move_unreachable's 'young' |
| * list, and move_unreachable will eventually get to it. |
| * If gc_refs == GC_REACHABLE, it's either in some other |
| * generation so we don't care about it, or move_unreachable |
| * already dealt with it. |
| * If gc_refs == GC_UNTRACKED, it must be ignored. |
| */ |
| else { |
| assert(gc_refs > 0 |
| || gc_refs == GC_REACHABLE |
| || gc_refs == GC_UNTRACKED); |
| } |
| } |
| return 0; |
| } |
| |
| /* Move the unreachable objects from young to unreachable. After this, |
| * all objects in young have gc_refs = GC_REACHABLE, and all objects in |
| * unreachable have gc_refs = GC_TENTATIVELY_UNREACHABLE. All tracked |
| * gc objects not in young or unreachable still have gc_refs = GC_REACHABLE. |
| * All objects in young after this are directly or indirectly reachable |
| * from outside the original young; and all objects in unreachable are |
| * not. |
| */ |
| static void |
| move_unreachable(PyGC_Head *young, PyGC_Head *unreachable) |
| { |
| PyGC_Head *gc = young->gc.gc_next; |
| |
| /* Invariants: all objects "to the left" of us in young have gc_refs |
| * = GC_REACHABLE, and are indeed reachable (directly or indirectly) |
| * from outside the young list as it was at entry. All other objects |
| * from the original young "to the left" of us are in unreachable now, |
| * and have gc_refs = GC_TENTATIVELY_UNREACHABLE. All objects to the |
| * left of us in 'young' now have been scanned, and no objects here |
| * or to the right have been scanned yet. |
| */ |
| |
| while (gc != young) { |
| PyGC_Head *next; |
| |
| if (gc->gc.gc_refs) { |
| /* gc is definitely reachable from outside the |
| * original 'young'. Mark it as such, and traverse |
| * its pointers to find any other objects that may |
| * be directly reachable from it. Note that the |
| * call to tp_traverse may append objects to young, |
| * so we have to wait until it returns to determine |
| * the next object to visit. |
| */ |
| PyObject *op = FROM_GC(gc); |
| traverseproc traverse = op->ob_type->tp_traverse; |
| assert(gc->gc.gc_refs > 0); |
| gc->gc.gc_refs = GC_REACHABLE; |
| (void) traverse(op, |
| (visitproc)visit_reachable, |
| (void *)young); |
| next = gc->gc.gc_next; |
| } |
| else { |
| /* This *may* be unreachable. To make progress, |
| * assume it is. gc isn't directly reachable from |
| * any object we've already traversed, but may be |
| * reachable from an object we haven't gotten to yet. |
| * visit_reachable will eventually move gc back into |
| * young if that's so, and we'll see it again. |
| */ |
| next = gc->gc.gc_next; |
| gc_list_move(gc, unreachable); |
| gc->gc.gc_refs = GC_TENTATIVELY_UNREACHABLE; |
| } |
| gc = next; |
| } |
| } |
| |
| /* Return true if object has a finalization method. |
| * CAUTION: An instance of an old-style class has to be checked for a |
| *__del__ method, and earlier versions of this used to call PyObject_HasAttr, |
| * which in turn could call the class's __getattr__ hook (if any). That |
| * could invoke arbitrary Python code, mutating the object graph in arbitrary |
| * ways, and that was the source of some excruciatingly subtle bugs. |
| */ |
| static int |
| has_finalizer(PyObject *op) |
| { |
| if (PyGen_CheckExact(op)) |
| return PyGen_NeedsFinalizing((PyGenObject *)op); |
| else |
| return op->ob_type->tp_del != NULL; |
| } |
| |
| /* Move the objects in unreachable with __del__ methods into `finalizers`. |
| * Objects moved into `finalizers` have gc_refs set to GC_REACHABLE; the |
| * objects remaining in unreachable are left at GC_TENTATIVELY_UNREACHABLE. |
| */ |
| static void |
| move_finalizers(PyGC_Head *unreachable, PyGC_Head *finalizers) |
| { |
| PyGC_Head *gc; |
| PyGC_Head *next; |
| |
| /* March over unreachable. Move objects with finalizers into |
| * `finalizers`. |
| */ |
| for (gc = unreachable->gc.gc_next; gc != unreachable; gc = next) { |
| PyObject *op = FROM_GC(gc); |
| |
| assert(IS_TENTATIVELY_UNREACHABLE(op)); |
| next = gc->gc.gc_next; |
| |
| if (has_finalizer(op)) { |
| gc_list_move(gc, finalizers); |
| gc->gc.gc_refs = GC_REACHABLE; |
| } |
| } |
| } |
| |
| /* A traversal callback for move_finalizer_reachable. */ |
| static int |
| visit_move(PyObject *op, PyGC_Head *tolist) |
| { |
| if (PyObject_IS_GC(op)) { |
| if (IS_TENTATIVELY_UNREACHABLE(op)) { |
| PyGC_Head *gc = AS_GC(op); |
| gc_list_move(gc, tolist); |
| gc->gc.gc_refs = GC_REACHABLE; |
| } |
| } |
| return 0; |
| } |
| |
| /* Move objects that are reachable from finalizers, from the unreachable set |
| * into finalizers set. |
| */ |
| static void |
| move_finalizer_reachable(PyGC_Head *finalizers) |
| { |
| traverseproc traverse; |
| PyGC_Head *gc = finalizers->gc.gc_next; |
| for (; gc != finalizers; gc = gc->gc.gc_next) { |
| /* Note that the finalizers list may grow during this. */ |
| traverse = FROM_GC(gc)->ob_type->tp_traverse; |
| (void) traverse(FROM_GC(gc), |
| (visitproc)visit_move, |
| (void *)finalizers); |
| } |
| } |
| |
| /* Clear all weakrefs to unreachable objects, and if such a weakref has a |
| * callback, invoke it if necessary. Note that it's possible for such |
| * weakrefs to be outside the unreachable set -- indeed, those are precisely |
| * the weakrefs whose callbacks must be invoked. See gc_weakref.txt for |
| * overview & some details. Some weakrefs with callbacks may be reclaimed |
| * directly by this routine; the number reclaimed is the return value. Other |
| * weakrefs with callbacks may be moved into the `old` generation. Objects |
| * moved into `old` have gc_refs set to GC_REACHABLE; the objects remaining in |
| * unreachable are left at GC_TENTATIVELY_UNREACHABLE. When this returns, |
| * no object in `unreachable` is weakly referenced anymore. |
| */ |
| static int |
| handle_weakrefs(PyGC_Head *unreachable, PyGC_Head *old) |
| { |
| PyGC_Head *gc; |
| PyObject *op; /* generally FROM_GC(gc) */ |
| PyWeakReference *wr; /* generally a cast of op */ |
| PyGC_Head wrcb_to_call; /* weakrefs with callbacks to call */ |
| PyGC_Head *next; |
| int num_freed = 0; |
| |
| gc_list_init(&wrcb_to_call); |
| |
| /* Clear all weakrefs to the objects in unreachable. If such a weakref |
| * also has a callback, move it into `wrcb_to_call` if the callback |
| * needs to be invoked. Note that we cannot invoke any callbacks until |
| * all weakrefs to unreachable objects are cleared, lest the callback |
| * resurrect an unreachable object via a still-active weakref. We |
| * make another pass over wrcb_to_call, invoking callbacks, after this |
| * pass completes. |
| */ |
| for (gc = unreachable->gc.gc_next; gc != unreachable; gc = next) { |
| PyWeakReference **wrlist; |
| |
| op = FROM_GC(gc); |
| assert(IS_TENTATIVELY_UNREACHABLE(op)); |
| next = gc->gc.gc_next; |
| |
| if (! PyType_SUPPORTS_WEAKREFS(op->ob_type)) |
| continue; |
| |
| /* It supports weakrefs. Does it have any? */ |
| wrlist = (PyWeakReference **) |
| PyObject_GET_WEAKREFS_LISTPTR(op); |
| |
| /* `op` may have some weakrefs. March over the list, clear |
| * all the weakrefs, and move the weakrefs with callbacks |
| * that must be called into wrcb_to_call. |
| */ |
| for (wr = *wrlist; wr != NULL; wr = *wrlist) { |
| PyGC_Head *wrasgc; /* AS_GC(wr) */ |
| |
| /* _PyWeakref_ClearRef clears the weakref but leaves |
| * the callback pointer intact. Obscure: it also |
| * changes *wrlist. |
| */ |
| assert(wr->wr_object == op); |
| _PyWeakref_ClearRef(wr); |
| assert(wr->wr_object == Py_None); |
| if (wr->wr_callback == NULL) |
| continue; /* no callback */ |
| |
| /* Headache time. `op` is going away, and is weakly referenced by |
| * `wr`, which has a callback. Should the callback be invoked? If wr |
| * is also trash, no: |
| * |
| * 1. There's no need to call it. The object and the weakref are |
| * both going away, so it's legitimate to pretend the weakref is |
| * going away first. The user has to ensure a weakref outlives its |
| * referent if they want a guarantee that the wr callback will get |
| * invoked. |
| * |
| * 2. It may be catastrophic to call it. If the callback is also in |
| * cyclic trash (CT), then although the CT is unreachable from |
| * outside the current generation, CT may be reachable from the |
| * callback. Then the callback could resurrect insane objects. |
| * |
| * Since the callback is never needed and may be unsafe in this case, |
| * wr is simply left in the unreachable set. Note that because we |
| * already called _PyWeakref_ClearRef(wr), its callback will never |
| * trigger. |
| * |
| * OTOH, if wr isn't part of CT, we should invoke the callback: the |
| * weakref outlived the trash. Note that since wr isn't CT in this |
| * case, its callback can't be CT either -- wr acted as an external |
| * root to this generation, and therefore its callback did too. So |
| * nothing in CT is reachable from the callback either, so it's hard |
| * to imagine how calling it later could create a problem for us. wr |
| * is moved to wrcb_to_call in this case. |
| */ |
| if (IS_TENTATIVELY_UNREACHABLE(wr)) |
| continue; |
| assert(IS_REACHABLE(wr)); |
| |
| /* Create a new reference so that wr can't go away |
| * before we can process it again. |
| */ |
| Py_INCREF(wr); |
| |
| /* Move wr to wrcb_to_call, for the next pass. */ |
| wrasgc = AS_GC(wr); |
| assert(wrasgc != next); /* wrasgc is reachable, but |
| next isn't, so they can't |
| be the same */ |
| gc_list_move(wrasgc, &wrcb_to_call); |
| } |
| } |
| |
| /* Invoke the callbacks we decided to honor. It's safe to invoke them |
| * because they can't reference unreachable objects. |
| */ |
| while (! gc_list_is_empty(&wrcb_to_call)) { |
| PyObject *temp; |
| PyObject *callback; |
| |
| gc = wrcb_to_call.gc.gc_next; |
| op = FROM_GC(gc); |
| assert(IS_REACHABLE(op)); |
| assert(PyWeakref_Check(op)); |
| wr = (PyWeakReference *)op; |
| callback = wr->wr_callback; |
| assert(callback != NULL); |
| |
| /* copy-paste of weakrefobject.c's handle_callback() */ |
| temp = PyObject_CallFunctionObjArgs(callback, wr, NULL); |
| if (temp == NULL) |
| PyErr_WriteUnraisable(callback); |
| else |
| Py_DECREF(temp); |
| |
| /* Give up the reference we created in the first pass. When |
| * op's refcount hits 0 (which it may or may not do right now), |
| * op's tp_dealloc will decref op->wr_callback too. Note |
| * that the refcount probably will hit 0 now, and because this |
| * weakref was reachable to begin with, gc didn't already |
| * add it to its count of freed objects. Example: a reachable |
| * weak value dict maps some key to this reachable weakref. |
| * The callback removes this key->weakref mapping from the |
| * dict, leaving no other references to the weakref (excepting |
| * ours). |
| */ |
| Py_DECREF(op); |
| if (wrcb_to_call.gc.gc_next == gc) { |
| /* object is still alive -- move it */ |
| gc_list_move(gc, old); |
| } |
| else |
| ++num_freed; |
| } |
| |
| return num_freed; |
| } |
| |
| static void |
| debug_cycle(char *msg, PyObject *op) |
| { |
| if (debug & DEBUG_OBJECTS) { |
| PySys_WriteStderr("gc: %.100s <%.100s %p>\n", |
| msg, op->ob_type->tp_name, op); |
| } |
| } |
| |
| /* Handle uncollectable garbage (cycles with finalizers, and stuff reachable |
| * only from such cycles). |
| * If DEBUG_SAVEALL, all objects in finalizers are appended to the module |
| * garbage list (a Python list), else only the objects in finalizers with |
| * __del__ methods are appended to garbage. All objects in finalizers are |
| * merged into the old list regardless. |
| * Returns 0 if all OK, <0 on error (out of memory to grow the garbage list). |
| * The finalizers list is made empty on a successful return. |
| */ |
| static int |
| handle_finalizers(PyGC_Head *finalizers, PyGC_Head *old) |
| { |
| PyGC_Head *gc = finalizers->gc.gc_next; |
| |
| if (garbage == NULL) { |
| garbage = PyList_New(0); |
| if (garbage == NULL) |
| Py_FatalError("gc couldn't create gc.garbage list"); |
| } |
| for (; gc != finalizers; gc = gc->gc.gc_next) { |
| PyObject *op = FROM_GC(gc); |
| |
| if ((debug & DEBUG_SAVEALL) || has_finalizer(op)) { |
| if (PyList_Append(garbage, op) < 0) |
| return -1; |
| } |
| } |
| |
| gc_list_merge(finalizers, old); |
| return 0; |
| } |
| |
| /* Break reference cycles by clearing the containers involved. This is |
| * tricky business as the lists can be changing and we don't know which |
| * objects may be freed. It is possible I screwed something up here. |
| */ |
| static void |
| delete_garbage(PyGC_Head *collectable, PyGC_Head *old) |
| { |
| inquiry clear; |
| |
| while (!gc_list_is_empty(collectable)) { |
| PyGC_Head *gc = collectable->gc.gc_next; |
| PyObject *op = FROM_GC(gc); |
| |
| assert(IS_TENTATIVELY_UNREACHABLE(op)); |
| if (debug & DEBUG_SAVEALL) { |
| PyList_Append(garbage, op); |
| } |
| else { |
| if ((clear = op->ob_type->tp_clear) != NULL) { |
| Py_INCREF(op); |
| clear(op); |
| Py_DECREF(op); |
| } |
| } |
| if (collectable->gc.gc_next == gc) { |
| /* object is still alive, move it, it may die later */ |
| gc_list_move(gc, old); |
| gc->gc.gc_refs = GC_REACHABLE; |
| } |
| } |
| } |
| |
| /* This is the main function. Read this to understand how the |
| * collection process works. */ |
| static Py_ssize_t |
| collect(int generation) |
| { |
| int i; |
| Py_ssize_t m = 0; /* # objects collected */ |
| Py_ssize_t n = 0; /* # unreachable objects that couldn't be collected */ |
| PyGC_Head *young; /* the generation we are examining */ |
| PyGC_Head *old; /* next older generation */ |
| PyGC_Head unreachable; /* non-problematic unreachable trash */ |
| PyGC_Head finalizers; /* objects with, & reachable from, __del__ */ |
| PyGC_Head *gc; |
| double t1 = 0.0; |
| |
| if (delstr == NULL) { |
| delstr = PyUnicode_InternFromString("__del__"); |
| if (delstr == NULL) |
| Py_FatalError("gc couldn't allocate \"__del__\""); |
| } |
| |
| if (debug & DEBUG_STATS) { |
| if (tmod != NULL) { |
| PyObject *f = PyObject_CallMethod(tmod, "time", NULL); |
| if (f == NULL) { |
| PyErr_Clear(); |
| } |
| else { |
| t1 = PyFloat_AsDouble(f); |
| Py_DECREF(f); |
| } |
| } |
| PySys_WriteStderr("gc: collecting generation %d...\n", |
| generation); |
| PySys_WriteStderr("gc: objects in each generation:"); |
| for (i = 0; i < NUM_GENERATIONS; i++) |
| PySys_WriteStderr(" %" PY_FORMAT_SIZE_T "d", |
| gc_list_size(GEN_HEAD(i))); |
| PySys_WriteStderr("\n"); |
| } |
| |
| /* update collection and allocation counters */ |
| if (generation+1 < NUM_GENERATIONS) |
| generations[generation+1].count += 1; |
| for (i = 0; i <= generation; i++) |
| generations[i].count = 0; |
| |
| /* merge younger generations with one we are currently collecting */ |
| for (i = 0; i < generation; i++) { |
| gc_list_merge(GEN_HEAD(i), GEN_HEAD(generation)); |
| } |
| |
| /* handy references */ |
| young = GEN_HEAD(generation); |
| if (generation < NUM_GENERATIONS-1) |
| old = GEN_HEAD(generation+1); |
| else |
| old = young; |
| |
| /* Using ob_refcnt and gc_refs, calculate which objects in the |
| * container set are reachable from outside the set (i.e., have a |
| * refcount greater than 0 when all the references within the |
| * set are taken into account). |
| */ |
| update_refs(young); |
| subtract_refs(young); |
| |
| /* Leave everything reachable from outside young in young, and move |
| * everything else (in young) to unreachable. |
| * NOTE: This used to move the reachable objects into a reachable |
| * set instead. But most things usually turn out to be reachable, |
| * so it's more efficient to move the unreachable things. |
| */ |
| gc_list_init(&unreachable); |
| move_unreachable(young, &unreachable); |
| |
| /* Move reachable objects to next generation. */ |
| if (young != old) |
| gc_list_merge(young, old); |
| |
| /* All objects in unreachable are trash, but objects reachable from |
| * finalizers can't safely be deleted. Python programmers should take |
| * care not to create such things. For Python, finalizers means |
| * instance objects with __del__ methods. Weakrefs with callbacks |
| * can also call arbitrary Python code but they will be dealt with by |
| * handle_weakrefs(). |
| */ |
| gc_list_init(&finalizers); |
| move_finalizers(&unreachable, &finalizers); |
| /* finalizers contains the unreachable objects with a finalizer; |
| * unreachable objects reachable *from* those are also uncollectable, |
| * and we move those into the finalizers list too. |
| */ |
| move_finalizer_reachable(&finalizers); |
| |
| /* Collect statistics on collectable objects found and print |
| * debugging information. |
| */ |
| for (gc = unreachable.gc.gc_next; gc != &unreachable; |
| gc = gc->gc.gc_next) { |
| m++; |
| if (debug & DEBUG_COLLECTABLE) { |
| debug_cycle("collectable", FROM_GC(gc)); |
| } |
| if (tmod != NULL && (debug & DEBUG_STATS)) { |
| PyObject *f = PyObject_CallMethod(tmod, "time", NULL); |
| if (f == NULL) { |
| PyErr_Clear(); |
| } |
| else { |
| t1 = PyFloat_AsDouble(f)-t1; |
| Py_DECREF(f); |
| PySys_WriteStderr("gc: %.4fs elapsed.\n", t1); |
| } |
| } |
| } |
| |
| /* Clear weakrefs and invoke callbacks as necessary. */ |
| m += handle_weakrefs(&unreachable, old); |
| |
| /* Call tp_clear on objects in the unreachable set. This will cause |
| * the reference cycles to be broken. It may also cause some objects |
| * in finalizers to be freed. |
| */ |
| delete_garbage(&unreachable, old); |
| |
| /* Collect statistics on uncollectable objects found and print |
| * debugging information. */ |
| for (gc = finalizers.gc.gc_next; |
| gc != &finalizers; |
| gc = gc->gc.gc_next) { |
| n++; |
| if (debug & DEBUG_UNCOLLECTABLE) |
| debug_cycle("uncollectable", FROM_GC(gc)); |
| } |
| if (debug & DEBUG_STATS) { |
| if (m == 0 && n == 0) |
| PySys_WriteStderr("gc: done.\n"); |
| else |
| PySys_WriteStderr( |
| "gc: done, " |
| "%" PY_FORMAT_SIZE_T "d unreachable, " |
| "%" PY_FORMAT_SIZE_T "d uncollectable.\n", |
| n+m, n); |
| } |
| |
| /* Append instances in the uncollectable set to a Python |
| * reachable list of garbage. The programmer has to deal with |
| * this if they insist on creating this type of structure. |
| */ |
| (void)handle_finalizers(&finalizers, old); |
| |
| if (PyErr_Occurred()) { |
| if (gc_str == NULL) |
| gc_str = PyString_FromString("garbage collection"); |
| PyErr_WriteUnraisable(gc_str); |
| Py_FatalError("unexpected exception during garbage collection"); |
| } |
| return n+m; |
| } |
| |
| static Py_ssize_t |
| collect_generations(void) |
| { |
| int i; |
| Py_ssize_t n = 0; |
| |
| /* Find the oldest generation (higest numbered) where the count |
| * exceeds the threshold. Objects in the that generation and |
| * generations younger than it will be collected. */ |
| for (i = NUM_GENERATIONS-1; i >= 0; i--) { |
| if (generations[i].count > generations[i].threshold) { |
| n = collect(i); |
| break; |
| } |
| } |
| return n; |
| } |
| |
| PyDoc_STRVAR(gc_enable__doc__, |
| "enable() -> None\n" |
| "\n" |
| "Enable automatic garbage collection.\n"); |
| |
| static PyObject * |
| gc_enable(PyObject *self, PyObject *noargs) |
| { |
| enabled = 1; |
| Py_INCREF(Py_None); |
| return Py_None; |
| } |
| |
| PyDoc_STRVAR(gc_disable__doc__, |
| "disable() -> None\n" |
| "\n" |
| "Disable automatic garbage collection.\n"); |
| |
| static PyObject * |
| gc_disable(PyObject *self, PyObject *noargs) |
| { |
| enabled = 0; |
| Py_INCREF(Py_None); |
| return Py_None; |
| } |
| |
| PyDoc_STRVAR(gc_isenabled__doc__, |
| "isenabled() -> status\n" |
| "\n" |
| "Returns true if automatic garbage collection is enabled.\n"); |
| |
| static PyObject * |
| gc_isenabled(PyObject *self, PyObject *noargs) |
| { |
| return PyBool_FromLong((long)enabled); |
| } |
| |
| PyDoc_STRVAR(gc_collect__doc__, |
| "collect([generation]) -> n\n" |
| "\n" |
| "With no arguments, run a full collection. The optional argument\n" |
| "may be an integer specifying which generation to collect. A ValueError\n" |
| "is raised if the generation number is invalid.\n\n" |
| "The number of unreachable objects is returned.\n"); |
| |
| static PyObject * |
| gc_collect(PyObject *self, PyObject *args, PyObject *kws) |
| { |
| static char *keywords[] = {"generation", NULL}; |
| int genarg = NUM_GENERATIONS - 1; |
| Py_ssize_t n; |
| |
| if (!PyArg_ParseTupleAndKeywords(args, kws, "|i", keywords, &genarg)) |
| return NULL; |
| |
| else if (genarg < 0 || genarg >= NUM_GENERATIONS) { |
| PyErr_SetString(PyExc_ValueError, "invalid generation"); |
| return NULL; |
| } |
| |
| if (collecting) |
| n = 0; /* already collecting, don't do anything */ |
| else { |
| collecting = 1; |
| n = collect(genarg); |
| collecting = 0; |
| } |
| |
| return PyInt_FromSsize_t(n); |
| } |
| |
| PyDoc_STRVAR(gc_set_debug__doc__, |
| "set_debug(flags) -> None\n" |
| "\n" |
| "Set the garbage collection debugging flags. Debugging information is\n" |
| "written to sys.stderr.\n" |
| "\n" |
| "flags is an integer and can have the following bits turned on:\n" |
| "\n" |
| " DEBUG_STATS - Print statistics during collection.\n" |
| " DEBUG_COLLECTABLE - Print collectable objects found.\n" |
| " DEBUG_UNCOLLECTABLE - Print unreachable but uncollectable objects found.\n" |
| " DEBUG_OBJECTS - Print objects other than instances.\n" |
| " DEBUG_SAVEALL - Save objects to gc.garbage rather than freeing them.\n" |
| " DEBUG_LEAK - Debug leaking programs (everything but STATS).\n"); |
| |
| static PyObject * |
| gc_set_debug(PyObject *self, PyObject *args) |
| { |
| if (!PyArg_ParseTuple(args, "i:set_debug", &debug)) |
| return NULL; |
| |
| Py_INCREF(Py_None); |
| return Py_None; |
| } |
| |
| PyDoc_STRVAR(gc_get_debug__doc__, |
| "get_debug() -> flags\n" |
| "\n" |
| "Get the garbage collection debugging flags.\n"); |
| |
| static PyObject * |
| gc_get_debug(PyObject *self, PyObject *noargs) |
| { |
| return Py_BuildValue("i", debug); |
| } |
| |
| PyDoc_STRVAR(gc_set_thresh__doc__, |
| "set_threshold(threshold0, [threshold1, threshold2]) -> None\n" |
| "\n" |
| "Sets the collection thresholds. Setting threshold0 to zero disables\n" |
| "collection.\n"); |
| |
| static PyObject * |
| gc_set_thresh(PyObject *self, PyObject *args) |
| { |
| int i; |
| if (!PyArg_ParseTuple(args, "i|ii:set_threshold", |
| &generations[0].threshold, |
| &generations[1].threshold, |
| &generations[2].threshold)) |
| return NULL; |
| for (i = 2; i < NUM_GENERATIONS; i++) { |
| /* generations higher than 2 get the same threshold */ |
| generations[i].threshold = generations[2].threshold; |
| } |
| |
| Py_INCREF(Py_None); |
| return Py_None; |
| } |
| |
| PyDoc_STRVAR(gc_get_thresh__doc__, |
| "get_threshold() -> (threshold0, threshold1, threshold2)\n" |
| "\n" |
| "Return the current collection thresholds\n"); |
| |
| static PyObject * |
| gc_get_thresh(PyObject *self, PyObject *noargs) |
| { |
| return Py_BuildValue("(iii)", |
| generations[0].threshold, |
| generations[1].threshold, |
| generations[2].threshold); |
| } |
| |
| PyDoc_STRVAR(gc_get_count__doc__, |
| "get_count() -> (count0, count1, count2)\n" |
| "\n" |
| "Return the current collection counts\n"); |
| |
| static PyObject * |
| gc_get_count(PyObject *self, PyObject *noargs) |
| { |
| return Py_BuildValue("(iii)", |
| generations[0].count, |
| generations[1].count, |
| generations[2].count); |
| } |
| |
| static int |
| referrersvisit(PyObject* obj, PyObject *objs) |
| { |
| Py_ssize_t i; |
| for (i = 0; i < PyTuple_GET_SIZE(objs); i++) |
| if (PyTuple_GET_ITEM(objs, i) == obj) |
| return 1; |
| return 0; |
| } |
| |
| static int |
| gc_referrers_for(PyObject *objs, PyGC_Head *list, PyObject *resultlist) |
| { |
| PyGC_Head *gc; |
| PyObject *obj; |
| traverseproc traverse; |
| for (gc = list->gc.gc_next; gc != list; gc = gc->gc.gc_next) { |
| obj = FROM_GC(gc); |
| traverse = obj->ob_type->tp_traverse; |
| if (obj == objs || obj == resultlist) |
| continue; |
| if (traverse(obj, (visitproc)referrersvisit, objs)) { |
| if (PyList_Append(resultlist, obj) < 0) |
| return 0; /* error */ |
| } |
| } |
| return 1; /* no error */ |
| } |
| |
| PyDoc_STRVAR(gc_get_referrers__doc__, |
| "get_referrers(*objs) -> list\n\ |
| Return the list of objects that directly refer to any of objs."); |
| |
| static PyObject * |
| gc_get_referrers(PyObject *self, PyObject *args) |
| { |
| int i; |
| PyObject *result = PyList_New(0); |
| if (!result) return NULL; |
| |
| for (i = 0; i < NUM_GENERATIONS; i++) { |
| if (!(gc_referrers_for(args, GEN_HEAD(i), result))) { |
| Py_DECREF(result); |
| return NULL; |
| } |
| } |
| return result; |
| } |
| |
| /* Append obj to list; return true if error (out of memory), false if OK. */ |
| static int |
| referentsvisit(PyObject *obj, PyObject *list) |
| { |
| return PyList_Append(list, obj) < 0; |
| } |
| |
| PyDoc_STRVAR(gc_get_referents__doc__, |
| "get_referents(*objs) -> list\n\ |
| Return the list of objects that are directly referred to by objs."); |
| |
| static PyObject * |
| gc_get_referents(PyObject *self, PyObject *args) |
| { |
| Py_ssize_t i; |
| PyObject *result = PyList_New(0); |
| |
| if (result == NULL) |
| return NULL; |
| |
| for (i = 0; i < PyTuple_GET_SIZE(args); i++) { |
| traverseproc traverse; |
| PyObject *obj = PyTuple_GET_ITEM(args, i); |
| |
| if (! PyObject_IS_GC(obj)) |
| continue; |
| traverse = obj->ob_type->tp_traverse; |
| if (! traverse) |
| continue; |
| if (traverse(obj, (visitproc)referentsvisit, result)) { |
| Py_DECREF(result); |
| return NULL; |
| } |
| } |
| return result; |
| } |
| |
| PyDoc_STRVAR(gc_get_objects__doc__, |
| "get_objects() -> [...]\n" |
| "\n" |
| "Return a list of objects tracked by the collector (excluding the list\n" |
| "returned).\n"); |
| |
| static PyObject * |
| gc_get_objects(PyObject *self, PyObject *noargs) |
| { |
| int i; |
| PyObject* result; |
| |
| result = PyList_New(0); |
| if (result == NULL) |
| return NULL; |
| for (i = 0; i < NUM_GENERATIONS; i++) { |
| if (append_objects(result, GEN_HEAD(i))) { |
| Py_DECREF(result); |
| return NULL; |
| } |
| } |
| return result; |
| } |
| |
| |
| PyDoc_STRVAR(gc__doc__, |
| "This module provides access to the garbage collector for reference cycles.\n" |
| "\n" |
| "enable() -- Enable automatic garbage collection.\n" |
| "disable() -- Disable automatic garbage collection.\n" |
| "isenabled() -- Returns true if automatic collection is enabled.\n" |
| "collect() -- Do a full collection right now.\n" |
| "get_count() -- Return the current collection counts.\n" |
| "set_debug() -- Set debugging flags.\n" |
| "get_debug() -- Get debugging flags.\n" |
| "set_threshold() -- Set the collection thresholds.\n" |
| "get_threshold() -- Return the current the collection thresholds.\n" |
| "get_objects() -- Return a list of all objects tracked by the collector.\n" |
| "get_referrers() -- Return the list of objects that refer to an object.\n" |
| "get_referents() -- Return the list of objects that an object refers to.\n"); |
| |
| static PyMethodDef GcMethods[] = { |
| {"enable", gc_enable, METH_NOARGS, gc_enable__doc__}, |
| {"disable", gc_disable, METH_NOARGS, gc_disable__doc__}, |
| {"isenabled", gc_isenabled, METH_NOARGS, gc_isenabled__doc__}, |
| {"set_debug", gc_set_debug, METH_VARARGS, gc_set_debug__doc__}, |
| {"get_debug", gc_get_debug, METH_NOARGS, gc_get_debug__doc__}, |
| {"get_count", gc_get_count, METH_NOARGS, gc_get_count__doc__}, |
| {"set_threshold", gc_set_thresh, METH_VARARGS, gc_set_thresh__doc__}, |
| {"get_threshold", gc_get_thresh, METH_NOARGS, gc_get_thresh__doc__}, |
| {"collect", (PyCFunction)gc_collect, |
| METH_VARARGS | METH_KEYWORDS, gc_collect__doc__}, |
| {"get_objects", gc_get_objects,METH_NOARGS, gc_get_objects__doc__}, |
| {"get_referrers", gc_get_referrers, METH_VARARGS, |
| gc_get_referrers__doc__}, |
| {"get_referents", gc_get_referents, METH_VARARGS, |
| gc_get_referents__doc__}, |
| {NULL, NULL} /* Sentinel */ |
| }; |
| |
| PyMODINIT_FUNC |
| initgc(void) |
| { |
| PyObject *m; |
| |
| m = Py_InitModule4("gc", |
| GcMethods, |
| gc__doc__, |
| NULL, |
| PYTHON_API_VERSION); |
| if (m == NULL) |
| return; |
| |
| if (garbage == NULL) { |
| garbage = PyList_New(0); |
| if (garbage == NULL) |
| return; |
| } |
| Py_INCREF(garbage); |
| if (PyModule_AddObject(m, "garbage", garbage) < 0) |
| return; |
| |
| /* Importing can't be done in collect() because collect() |
| * can be called via PyGC_Collect() in Py_Finalize(). |
| * This wouldn't be a problem, except that <initialized> is |
| * reset to 0 before calling collect which trips up |
| * the import and triggers an assertion. |
| */ |
| if (tmod == NULL) { |
| tmod = PyImport_ImportModule("time"); |
| if (tmod == NULL) |
| PyErr_Clear(); |
| } |
| |
| #define ADD_INT(NAME) if (PyModule_AddIntConstant(m, #NAME, NAME) < 0) return |
| ADD_INT(DEBUG_STATS); |
| ADD_INT(DEBUG_COLLECTABLE); |
| ADD_INT(DEBUG_UNCOLLECTABLE); |
| ADD_INT(DEBUG_OBJECTS); |
| ADD_INT(DEBUG_SAVEALL); |
| ADD_INT(DEBUG_LEAK); |
| #undef ADD_INT |
| } |
| |
| /* API to invoke gc.collect() from C */ |
| Py_ssize_t |
| PyGC_Collect(void) |
| { |
| Py_ssize_t n; |
| |
| if (collecting) |
| n = 0; /* already collecting, don't do anything */ |
| else { |
| collecting = 1; |
| n = collect(NUM_GENERATIONS - 1); |
| collecting = 0; |
| } |
| |
| return n; |
| } |
| |
| /* for debugging */ |
| void |
| _PyGC_Dump(PyGC_Head *g) |
| { |
| _PyObject_Dump(FROM_GC(g)); |
| } |
| |
| /* extension modules might be compiled with GC support so these |
| functions must always be available */ |
| |
| #undef PyObject_GC_Track |
| #undef PyObject_GC_UnTrack |
| #undef PyObject_GC_Del |
| #undef _PyObject_GC_Malloc |
| |
| void |
| PyObject_GC_Track(void *op) |
| { |
| _PyObject_GC_TRACK(op); |
| } |
| |
| /* for binary compatibility with 2.2 */ |
| void |
| _PyObject_GC_Track(PyObject *op) |
| { |
| PyObject_GC_Track(op); |
| } |
| |
| void |
| PyObject_GC_UnTrack(void *op) |
| { |
| /* Obscure: the Py_TRASHCAN mechanism requires that we be able to |
| * call PyObject_GC_UnTrack twice on an object. |
| */ |
| if (IS_TRACKED(op)) |
| _PyObject_GC_UNTRACK(op); |
| } |
| |
| /* for binary compatibility with 2.2 */ |
| void |
| _PyObject_GC_UnTrack(PyObject *op) |
| { |
| PyObject_GC_UnTrack(op); |
| } |
| |
| PyObject * |
| _PyObject_GC_Malloc(size_t basicsize) |
| { |
| PyObject *op; |
| PyGC_Head *g = (PyGC_Head *)PyObject_MALLOC( |
| sizeof(PyGC_Head) + basicsize); |
| if (g == NULL) |
| return PyErr_NoMemory(); |
| g->gc.gc_refs = GC_UNTRACKED; |
| generations[0].count++; /* number of allocated GC objects */ |
| if (generations[0].count > generations[0].threshold && |
| enabled && |
| generations[0].threshold && |
| !collecting && |
| !PyErr_Occurred()) { |
| collecting = 1; |
| collect_generations(); |
| collecting = 0; |
| } |
| op = FROM_GC(g); |
| return op; |
| } |
| |
| PyObject * |
| _PyObject_GC_New(PyTypeObject *tp) |
| { |
| PyObject *op = _PyObject_GC_Malloc(_PyObject_SIZE(tp)); |
| if (op != NULL) |
| op = PyObject_INIT(op, tp); |
| return op; |
| } |
| |
| PyVarObject * |
| _PyObject_GC_NewVar(PyTypeObject *tp, Py_ssize_t nitems) |
| { |
| const size_t size = _PyObject_VAR_SIZE(tp, nitems); |
| PyVarObject *op = (PyVarObject *) _PyObject_GC_Malloc(size); |
| if (op != NULL) |
| op = PyObject_INIT_VAR(op, tp, nitems); |
| return op; |
| } |
| |
| PyVarObject * |
| _PyObject_GC_Resize(PyVarObject *op, Py_ssize_t nitems) |
| { |
| const size_t basicsize = _PyObject_VAR_SIZE(op->ob_type, nitems); |
| PyGC_Head *g = AS_GC(op); |
| g = (PyGC_Head *)PyObject_REALLOC(g, sizeof(PyGC_Head) + basicsize); |
| if (g == NULL) |
| return (PyVarObject *)PyErr_NoMemory(); |
| op = (PyVarObject *) FROM_GC(g); |
| op->ob_size = nitems; |
| return op; |
| } |
| |
| void |
| PyObject_GC_Del(void *op) |
| { |
| PyGC_Head *g = AS_GC(op); |
| if (IS_TRACKED(op)) |
| gc_list_remove(g); |
| if (generations[0].count > 0) { |
| generations[0].count--; |
| } |
| PyObject_FREE(g); |
| } |
| |
| /* for binary compatibility with 2.2 */ |
| #undef _PyObject_GC_Del |
| void |
| _PyObject_GC_Del(PyObject *op) |
| { |
| PyObject_GC_Del(op); |
| } |