Panda3D
referenceCount.cxx
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1 /**
2  * PANDA 3D SOFTWARE
3  * Copyright (c) Carnegie Mellon University. All rights reserved.
4  *
5  * All use of this software is subject to the terms of the revised BSD
6  * license. You should have received a copy of this license along
7  * with this source code in a file named "LICENSE."
8  *
9  * @file referenceCount.cxx
10  * @author drose
11  * @date 1998-10-23
12  */
13 
14 #include "referenceCount.h"
15 #include "atomicAdjust.h"
16 #include "mutexImpl.h"
17 
18 TypeHandle ReferenceCount::_type_handle;
19 
20 /**
21  * Does some easy checks to make sure that the reference count isn't
22  * completely bogus. Returns true if ok, false otherwise.
23  */
24 bool ReferenceCount::
25 do_test_ref_count_integrity() const {
26  // If this assertion fails, we're trying to delete an object that was just
27  // deleted. Possibly you used a real pointer instead of a PointerTo at some
28  // point, and the object was deleted when the PointerTo went out of scope.
29  // Maybe you tried to create an automatic (local variable) instance of a
30  // class that derives from ReferenceCount. Or maybe your headers are out of
31  // sync, and you need to make clean in direct or some higher tree.
32  nassertr(_ref_count != deleted_ref_count, false);
33 
34  // If this assertion fails, the reference counts are all screwed up
35  // altogether. Maybe some errant code stomped all over memory somewhere.
36  nassertr(_ref_count >= 0, false);
37 
38  return true;
39 }
40 
41 /**
42  * Returns true if the reference count is nonzero, false otherwise.
43  */
44 bool ReferenceCount::
45 do_test_ref_count_nonzero() const {
46  nassertr(do_test_ref_count_integrity(), false);
47  nassertr(_ref_count > 0, false);
48 
49  return true;
50 }
51 
52 /**
53  * Allocates a new WeakReferenceList structure and stores it on the object.
54  */
55 void ReferenceCount::
56 create_weak_list() {
57  WeakReferenceList *weak_list = new WeakReferenceList;
58  void *orig =
59  AtomicAdjust::compare_and_exchange_ptr(_weak_list, nullptr, weak_list);
60  if (orig != nullptr) {
61  // Someone else created it first.
62  delete weak_list;
63  }
64 }
PANDA 3D SOFTWARE Copyright (c) Carnegie Mellon University.
This is an object shared by all the weak pointers that point to the same ReferenceCount object...
static ALWAYS_INLINE Pointer compare_and_exchange_ptr(Pointer &mem, Pointer old_value, Pointer new_value)
Atomic compare and exchange.
PANDA 3D SOFTWARE Copyright (c) Carnegie Mellon University.
TypeHandle is the identifier used to differentiate C++ class types.
Definition: typeHandle.h:81
PANDA 3D SOFTWARE Copyright (c) Carnegie Mellon University.