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juce_LeakedObjectDetector.h
1
2/** @weakgroup juce_core-memory
3 * @{
4 */
5/*
6 ==============================================================================
7
8 This file is part of the JUCE library.
9 Copyright (c) 2017 - ROLI Ltd.
10
11 JUCE is an open source library subject to commercial or open-source
12 licensing.
13
14 The code included in this file is provided under the terms of the ISC license
15 http://www.isc.org/downloads/software-support-policy/isc-license. Permission
16 To use, copy, modify, and/or distribute this software for any purpose with or
17 without fee is hereby granted provided that the above copyright notice and
18 this permission notice appear in all copies.
19
20 JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
21 EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
22 DISCLAIMED.
23
24 ==============================================================================
25*/
26
27namespace juce
28{
29
30//==============================================================================
31/**
32 Embedding an instance of this class inside another class can be used as a low-overhead
33 way of detecting leaked instances.
34
35 This class keeps an internal static count of the number of instances that are
36 active, so that when the app is shutdown and the static destructors are called,
37 it can check whether there are any left-over instances that may have been leaked.
38
39 To use it, use the JUCE_LEAK_DETECTOR macro as a simple way to put one in your
40 class declaration. Have a look through the juce codebase for examples, it's used
41 in most of the classes.
42
43 @tags{Core}
44*/
45template <class OwnerClass>
47{
48public:
49 //==============================================================================
50 LeakedObjectDetector() noexcept { ++(getCounter().numObjects); }
51 LeakedObjectDetector (const LeakedObjectDetector&) noexcept { ++(getCounter().numObjects); }
52
54 {
55 if (--(getCounter().numObjects) < 0)
56 {
57 DBG ("*** Dangling pointer deletion! Class: " << getLeakedObjectClassName());
58
59 /** If you hit this, then you've managed to delete more instances of this class than you've
60 created.. That indicates that you're deleting some dangling pointers.
61
62 Note that although this assertion will have been triggered during a destructor, it might
63 not be this particular deletion that's at fault - the incorrect one may have happened
64 at an earlier point in the program, and simply not been detected until now.
65
66 Most errors like this are caused by using old-fashioned, non-RAII techniques for
67 your object management. Tut, tut. Always, always use std::unique_ptrs, OwnedArrays,
68 ReferenceCountedObjects, etc, and avoid the 'delete' operator at all costs!
69 */
70 jassertfalse;
71 }
72 }
73
74private:
75 //==============================================================================
76 class LeakCounter
77 {
78 public:
79 LeakCounter() = default;
80
81 ~LeakCounter()
82 {
83 if (numObjects.value > 0)
84 {
85 DBG ("*** Leaked objects detected: " << numObjects.value << " instance(s) of class " << getLeakedObjectClassName());
86
87 /** If you hit this, then you've leaked one or more objects of the type specified by
88 the 'OwnerClass' template parameter - the name should have been printed by the line above.
89
90 If you're leaking, it's probably because you're using old-fashioned, non-RAII techniques for
91 your object management. Tut, tut. Always, always use std::unique_ptrs, OwnedArrays,
92 ReferenceCountedObjects, etc, and avoid the 'delete' operator at all costs!
93 */
94 jassertfalse;
95 }
96 }
97
98 Atomic<int> numObjects;
99 };
100
101 static const char* getLeakedObjectClassName()
102 {
103 return OwnerClass::getLeakedObjectClassName();
104 }
105
106 static LeakCounter& getCounter() noexcept
107 {
108 static LeakCounter counter;
109 return counter;
110 }
111};
112
113//==============================================================================
114#if DOXYGEN || ! defined (JUCE_LEAK_DETECTOR)
115 #if (DOXYGEN || JUCE_CHECK_MEMORY_LEAKS)
116 /** This macro lets you embed a leak-detecting object inside a class.
117
118 To use it, simply declare a JUCE_LEAK_DETECTOR(YourClassName) inside a private section
119 of the class declaration. E.g.
120
121 @code
122 class MyClass
123 {
124 public:
125 MyClass();
126 void blahBlah();
127
128 private:
129 JUCE_LEAK_DETECTOR (MyClass)
130 };
131 @endcode
132
133 @see JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR, LeakedObjectDetector
134 */
135 #define JUCE_LEAK_DETECTOR(OwnerClass) \
136 friend class juce::LeakedObjectDetector<OwnerClass>; \
137 static const char* getLeakedObjectClassName() noexcept { return #OwnerClass; } \
138 juce::LeakedObjectDetector<OwnerClass> JUCE_JOIN_MACRO (leakDetector, __LINE__);
139 #else
140 #define JUCE_LEAK_DETECTOR(OwnerClass)
141 #endif
142#endif
143
144} // namespace juce
145
146/** @}*/
Embedding an instance of this class inside another class can be used as a low-overhead way of detecti...