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object.h special-build macro minefield: renamed all the new lexical
helper macros to something saner, and used them appropriately in other files too, to reduce #ifdef blocks. classobject.c, instance_dealloc(): One of my worst Python Memories is trying to fix this routine a few years ago when COUNT_ALLOCS was defined but Py_TRACE_REFS wasn't. The special-build code here is way too complicated. Now it's much simpler. Difference: in a Py_TRACE_REFS build, the instance is no longer in the doubly-linked list of live objects while its __del__ method is executing, and that may be visible via sys.getobjects() called from a __del__ method. Tough -- the object is presumed dead while its __del__ is executing anyway, and not calling _Py_NewReference() at the start allows enormous code simplification. typeobject.c, call_finalizer(): The special-build instance_dealloc() pain apparently spread to here too via cut-'n-paste, and this is much simpler now too. In addition, I didn't understand why this routine was calling _PyObject_GC_TRACK() after a resurrection, since there's no plausible way _PyObject_GC_UNTRACK() could have been called on the object by this point. I suspect it was left over from pasting the instance_delloc() code. Instead asserted that the object is still tracked. Caution: I suspect we don't have a test that actually exercises the subtype_dealloc() __del__-resurrected-me code.
This commit is contained in:
Tim Peters
parent
dc1e70987f
commit
3459251d5a
6 changed files with 114 additions and 159 deletions
100
Include/object.h
100
Include/object.h
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@ -51,35 +51,10 @@ A standard interface exists for objects that contain an array of items
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whose size is determined when the object is allocated.
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*/
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#ifdef Py_DEBUG
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/* Turn on aggregate reference counting. This arranges that extern
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* _Py_RefTotal hold a count of all references, the sum of ob_refcnt
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* across all objects. The value can be gotten programatically via
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* sys.gettotalrefcount() (which exists only if Py_REF_DEBUG is enabled).
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* In a debug-mode build, this is where the "8288" comes from in
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*
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* >>> 23
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* 23
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* [8288 refs]
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* >>>
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*
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* Note that if this count increases when you're not storing away new objects,
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* there's probably a leak. Remember, though, that in interactive mode the
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* special name "_" holds a reference to the last result displayed!
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* Py_REF_DEBUG also checks after every decref to verify that the refcount
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* hasn't gone negative, and causes an immediate fatal error if it has.
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*/
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#define Py_REF_DEBUG
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/* Turn on heavy reference debugging. This is major surgery. Every PyObject
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* grows two more pointers, to maintain a doubly-linked list of all live
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* heap-allocated objects (note that, e.g., most builtin type objects are
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* not in this list, as they're statically allocated). This list can be
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* materialized into a Python list via sys.getobjects() (which exists only
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* if Py_TRACE_REFS is enabled). Py_TRACE_REFS implies Py_REF_DEBUG.
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*/
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/* Py_DEBUG implies Py_TRACE_REFS. */
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#if defined(Py_DEBUG) && !defined(Py_TRACE_REFS)
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#define Py_TRACE_REFS
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#endif /* Py_DEBUG */
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#endif
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/* Py_TRACE_REFS implies Py_REF_DEBUG. */
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#if defined(Py_TRACE_REFS) && !defined(Py_REF_DEBUG)
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@ -536,40 +511,45 @@ variable first, both of which are slower; and in a multi-threaded
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environment the global variable trick is not safe.)
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*/
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/* First define a pile of simple helper macros, one set per special
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* build symbol. These either expand to the obvious things, or to
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* nothing at all when the special mode isn't in effect. The main
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* macros can later be defined just once then, yet expand to different
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* things depending on which special build options are and aren't in effect.
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* Trust me <wink>: while painful, this is 20x easier to understand than,
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* e.g, defining _Py_NewReference five different times in a maze of nested
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* #ifdefs (we used to do that -- it was impenetrable).
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*/
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#ifdef Py_REF_DEBUG
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extern DL_IMPORT(long) _Py_RefTotal;
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extern DL_IMPORT(void) _Py_NegativeRefcount(const char *fname,
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int lineno, PyObject *op);
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#define _PyMAYBE_BUMP_REFTOTAL _Py_RefTotal++
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#define _PyMAYBE_DROP_REFTOTAL _Py_RefTotal--
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#define _PyMAYBE_BUMP_REFTOTAL_COMMA _PyMAYBE_BUMP_REFTOTAL ,
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#define _PyMAYBE_DROP_REFTOTAL_COMMA _PyMAYBE_DROP_REFTOTAL ,
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#define _PyMAYBE_CHECK_REFCNT(OP) \
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#define _Py_INC_REFTOTAL _Py_RefTotal++
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#define _Py_DEC_REFTOTAL _Py_RefTotal--
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#define _Py_REF_DEBUG_COMMA ,
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#define _Py_CHECK_REFCNT(OP) \
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{ if ((OP)->ob_refcnt < 0) \
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_Py_NegativeRefcount(__FILE__, __LINE__, \
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(PyObject *)(OP)); \
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}
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#else
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#define _PyMAYBE_BUMP_REFTOTAL
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#define _PyMAYBE_DROP_REFTOTAL
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#define _PyMAYBE_BUMP_REFTOTAL_COMMA
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#define _PyMAYBE_DROP_REFTOTAL_COMMA
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#define _PyMAYBE_CHECK_REFCNT(OP) /* a semicolon */;
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#define _Py_INC_REFTOTAL
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#define _Py_DEC_REFTOTAL
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#define _Py_REF_DEBUG_COMMA
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#define _Py_CHECK_REFCNT(OP) /* a semicolon */;
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#endif /* Py_REF_DEBUG */
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#ifdef COUNT_ALLOCS
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extern DL_IMPORT(void) inc_count(PyTypeObject *);
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#define _PyMAYBE_BUMP_COUNT(OP) inc_count((OP)->ob_type)
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#define _PyMAYBE_BUMP_FREECOUNT(OP) (OP)->ob_type->tp_frees++
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#define _PyMAYBE_DROP_FREECOUNT(OP) (OP)->ob_type->tp_frees--
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#define _PyMAYBE_BUMP_COUNT_COMMA(OP) _PyMAYBE_BUMP_COUNT(OP) ,
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#define _PyMAYBE_BUMP_FREECOUNT_COMMA(OP) _PyMAYBE_BUMP_FREECOUNT(OP) ,
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#define _Py_INC_TPALLOCS(OP) inc_count((OP)->ob_type)
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#define _Py_INC_TPFREES(OP) (OP)->ob_type->tp_frees++
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#define _Py_DEC_TPFREES(OP) (OP)->ob_type->tp_frees--
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#define _Py_COUNT_ALLOCS_COMMA ,
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#else
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#define _PyMAYBE_BUMP_COUNT(OP)
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#define _PyMAYBE_BUMP_FREECOUNT(OP)
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#define _PyMAYBE_DROP_FREECOUNT(OP)
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#define _PyMAYBE_BUMP_COUNT_COMMA(OP)
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#define _PyMAYBE_BUMP_FREECOUNT_COMMA(OP)
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#define _Py_INC_TPALLOCS(OP)
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#define _Py_INC_TPFREES(OP)
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#define _Py_DEC_TPFREES(OP)
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#define _Py_COUNT_ALLOCS_COMMA
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#endif /* COUNT_ALLOCS */
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#ifdef Py_TRACE_REFS
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@ -584,27 +564,27 @@ extern DL_IMPORT(void) _Py_ResetReferences(void);
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/* Without Py_TRACE_REFS, there's little enough to do that we expand code
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* inline.
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*/
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#define _Py_NewReference(op) ( \
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_PyMAYBE_BUMP_COUNT_COMMA(op) \
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_PyMAYBE_BUMP_REFTOTAL_COMMA \
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#define _Py_NewReference(op) ( \
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_Py_INC_TPALLOCS(op) _Py_COUNT_ALLOCS_COMMA \
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_Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \
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(op)->ob_refcnt = 1)
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#define _Py_ForgetReference(op) _PyMAYBE_BUMP_FREECOUNT(op)
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#define _Py_ForgetReference(op) _Py_INC_TPFREES(op)
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#define _Py_Dealloc(op) ( \
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_PyMAYBE_BUMP_FREECOUNT_COMMA(op) \
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_Py_INC_TPFREES(op) _Py_COUNT_ALLOCS_COMMA \
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(*(op)->ob_type->tp_dealloc)((PyObject *)(op)))
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#endif /* !Py_TRACE_REFS */
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#define Py_INCREF(op) ( \
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_PyMAYBE_BUMP_REFTOTAL_COMMA \
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#define Py_INCREF(op) ( \
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_Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \
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(op)->ob_refcnt++)
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#define Py_DECREF(op) \
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if (_PyMAYBE_DROP_REFTOTAL_COMMA \
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--(op)->ob_refcnt != 0) \
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_PyMAYBE_CHECK_REFCNT(op) \
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else \
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#define Py_DECREF(op) \
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if (_Py_DEC_REFTOTAL _Py_REF_DEBUG_COMMA \
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--(op)->ob_refcnt != 0) \
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_Py_CHECK_REFCNT(op) \
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else \
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_Py_Dealloc((PyObject *)(op))
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/* Macros to use in case the object pointer may be NULL: */
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