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Add Garbage Collection support to new-style classes (not yet to their
instances). Also added GC support to various auxiliary types: super, property, descriptors, wrappers, dictproxy. (Only type objects have a tp_clear field; the other types are.) One change was necessary to the GC infrastructure. We have statically allocated type objects that don't have a GC header (and can't easily be given one) and heap-allocated type objects that do have a GC header. Giving these different metatypes would be really ugly: I tried, and I had to modify pickle.py, cPickle.c, copy.py, add a new invent a new name for the new metatype and make it a built-in, change affected tests... In short, a mess. So instead, we add a new type slot tp_is_gc, which is a simple Boolean function that determines whether a particular instance has GC headers or not. This slot is only relevant for types that have the (new) GC flag bit set. If the tp_is_gc slot is NULL (by far the most common case), all instances of the type are deemed to have GC headers. This slot is called by the PyObject_IS_GC() macro (which is only used twice, both times in gcmodule.c). I also changed the extern declarations for a bunch of GC-related functions (_PyObject_GC_Del etc.): these always exist but objimpl.h only declared them when WITH_CYCLE_GC was defined, but I needed to be able to reference them without #ifdefs. (When WITH_CYCLE_GC is not defined, they do the same as their non-GC counterparts anyway.)
This commit is contained in:
Guido van Rossum
parent
0481d24dd5
commit
048eb75c2d
5 changed files with 237 additions and 39 deletions
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@ -265,7 +265,7 @@ subtype_dealloc(PyObject *self)
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/* Finalize GC if the base doesn't do GC and we do */
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if (PyType_IS_GC(type) && !PyType_IS_GC(base))
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PyObject_GC_Fini(self);
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_PyObject_GC_UNTRACK(self);
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/* Call the base tp_dealloc() */
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assert(f);
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@ -864,6 +864,8 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
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Py_TPFLAGS_BASETYPE;
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if (dynamic)
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type->tp_flags |= Py_TPFLAGS_DYNAMICTYPE;
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if (base->tp_flags & Py_TPFLAGS_HAVE_GC)
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type->tp_flags |= Py_TPFLAGS_HAVE_GC;
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/* It's a new-style number unless it specifically inherits any
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old-style numeric behavior */
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@ -934,7 +936,8 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
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else {
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if (add_dict) {
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if (base->tp_itemsize)
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type->tp_dictoffset = -(long)sizeof(PyObject *);
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type->tp_dictoffset =
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-(long)sizeof(PyObject *);
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else
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type->tp_dictoffset = slotoffset;
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slotoffset += sizeof(PyObject *);
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@ -966,7 +969,13 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
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/* Always override allocation strategy to use regular heap */
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type->tp_alloc = PyType_GenericAlloc;
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type->tp_free = _PyObject_Del;
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if (type->tp_flags & Py_TPFLAGS_HAVE_GC) {
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type->tp_free = _PyObject_GC_Del;
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type->tp_traverse = base->tp_traverse;
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type->tp_clear = base->tp_clear;
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}
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else
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type->tp_free = _PyObject_Del;
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/* Initialize the rest */
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if (PyType_Ready(type) < 0) {
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@ -1080,6 +1089,7 @@ type_dealloc(PyTypeObject *type)
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/* Assert this is a heap-allocated type object */
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assert(type->tp_flags & Py_TPFLAGS_HEAPTYPE);
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_PyObject_GC_UNTRACK(type);
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et = (etype *)type;
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Py_XDECREF(type->tp_base);
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Py_XDECREF(type->tp_dict);
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@ -1102,6 +1112,72 @@ static char type_doc[] =
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"type(object) -> the object's type\n"
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"type(name, bases, dict) -> a new type";
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static int
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type_traverse(PyTypeObject *type, visitproc visit, void *arg)
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{
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etype *et;
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int err;
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if (!(type->tp_flags & Py_TPFLAGS_HEAPTYPE))
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return 0;
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et = (etype *)type;
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#define VISIT(SLOT) \
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if (SLOT) { \
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err = visit((PyObject *)(SLOT), arg); \
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if (err) \
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return err; \
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}
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VISIT(type->tp_dict);
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VISIT(type->tp_defined);
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VISIT(type->tp_mro);
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VISIT(type->tp_bases);
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VISIT(type->tp_base);
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VISIT(et->slots);
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#undef VISIT
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return 0;
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}
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static int
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type_clear(PyTypeObject *type)
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{
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etype *et;
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PyObject *tmp;
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if (!(type->tp_flags & Py_TPFLAGS_HEAPTYPE))
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return 0;
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et = (etype *)type;
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#define CLEAR(SLOT) \
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if (SLOT) { \
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tmp = (PyObject *)(SLOT); \
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SLOT = NULL; \
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Py_DECREF(tmp); \
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}
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CLEAR(type->tp_dict);
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CLEAR(type->tp_defined);
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CLEAR(type->tp_mro);
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CLEAR(type->tp_bases);
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CLEAR(type->tp_base);
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CLEAR(et->slots);
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#undef CLEAR
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return 0;
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}
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static int
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type_is_gc(PyTypeObject *type)
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{
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return type->tp_flags & Py_TPFLAGS_HEAPTYPE;
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}
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PyTypeObject PyType_Type = {
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PyObject_HEAD_INIT(&PyType_Type)
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0, /* ob_size */
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@ -1123,10 +1199,11 @@ PyTypeObject PyType_Type = {
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(getattrofunc)type_getattro, /* tp_getattro */
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(setattrofunc)type_setattro, /* tp_setattro */
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0, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
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Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
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Py_TPFLAGS_BASETYPE, /* tp_flags */
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type_doc, /* tp_doc */
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0, /* tp_traverse */
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0, /* tp_clear */
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(traverseproc)type_traverse, /* tp_traverse */
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(inquiry)type_clear, /* tp_clear */
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0, /* tp_richcompare */
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0, /* tp_weaklistoffset */
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0, /* tp_iter */
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@ -1142,6 +1219,8 @@ PyTypeObject PyType_Type = {
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0, /* tp_init */
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0, /* tp_alloc */
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type_new, /* tp_new */
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_PyObject_GC_Del, /* tp_free */
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(inquiry)type_is_gc, /* tp_is_gc */
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};
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@ -3531,6 +3610,7 @@ super_dealloc(PyObject *self)
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{
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superobject *su = (superobject *)self;
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_PyObject_GC_UNTRACK(self);
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Py_XDECREF(su->obj);
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Py_XDECREF(su->type);
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self->ob_type->tp_free(self);
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@ -3666,6 +3746,27 @@ static char super_doc[] =
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" def meth(self, arg):\n"
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" super(C, self).meth(arg)";
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static int
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super_traverse(PyObject *self, visitproc visit, void *arg)
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{
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superobject *su = (superobject *)self;
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int err;
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#define VISIT(SLOT) \
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if (SLOT) { \
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err = visit((PyObject *)(SLOT), arg); \
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if (err) \
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return err; \
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}
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VISIT(su->obj);
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VISIT(su->type);
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#undef VISIT
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return 0;
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}
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PyTypeObject PySuper_Type = {
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PyObject_HEAD_INIT(&PyType_Type)
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0, /* ob_size */
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@ -3688,9 +3789,10 @@ PyTypeObject PySuper_Type = {
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super_getattro, /* tp_getattro */
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0, /* tp_setattro */
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0, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
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Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
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Py_TPFLAGS_BASETYPE, /* tp_flags */
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super_doc, /* tp_doc */
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0, /* tp_traverse */
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super_traverse, /* tp_traverse */
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0, /* tp_clear */
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0, /* tp_richcompare */
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0, /* tp_weaklistoffset */
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@ -3707,5 +3809,5 @@ PyTypeObject PySuper_Type = {
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super_init, /* tp_init */
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PyType_GenericAlloc, /* tp_alloc */
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PyType_GenericNew, /* tp_new */
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_PyObject_Del, /* tp_free */
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_PyObject_GC_Del, /* tp_free */
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};
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