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[gecko.git] / xpcom / glue / nsMemory.h
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1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
3 /* This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
7 #ifndef nsMemory_h__
8 #define nsMemory_h__
10 #include "nsXPCOM.h"
12 class nsIMemory;
14 #define NS_MEMORY_CONTRACTID "@mozilla.org/xpcom/memory-service;1"
15 #define NS_MEMORY_CID \
16 { /* 30a04e40-38e7-11d4-8cf5-0060b0fc14a3 */ \
17 0x30a04e40, \
18 0x38e7, \
19 0x11d4, \
20 {0x8c, 0xf5, 0x00, 0x60, 0xb0, 0xfc, 0x14, 0xa3} \
24 /**
25 * Static helper routines to manage memory. These routines allow easy access
26 * to xpcom's built-in (global) nsIMemory implementation, without needing
27 * to go through the service manager to get it. However this requires clients
28 * to link with the xpcom DLL.
30 * This class is not threadsafe and is intented for use only on the main
31 * thread.
33 class nsMemory
35 public:
36 static NS_HIDDEN_(void*) Alloc(size_t aSize)
38 return NS_Alloc(aSize);
41 static NS_HIDDEN_(void*) Realloc(void* aPtr, size_t aSize)
43 return NS_Realloc(aPtr, aSize);
46 static NS_HIDDEN_(void) Free(void* aPtr)
48 NS_Free(aPtr);
51 static nsresult HeapMinimize(bool aImmediate);
52 static void* Clone(const void* aPtr, size_t aSize);
53 static nsIMemory* GetGlobalMemoryService(); // AddRefs
56 /**
57 * Macro to free all elements of an XPCOM array of a given size using
58 * freeFunc, then frees the array itself using nsMemory::Free().
60 * Note that this macro (and its wrappers) can be used to deallocate a
61 * partially- or completely-built array while unwinding an error
62 * condition inside the XPCOM routine that was going to return the
63 * array. For this to work on a partially-built array, your code
64 * needs to be building the array from index 0 upwards, and simply
65 * pass the number of elements that have already been built (and thus
66 * need to be freed) as |size|.
68 * Thanks to <alecf@netscape.com> for suggesting this form, which
69 * allows the macro to be used with NS_RELEASE / NS_RELEASE_IF in
70 * addition to nsMemory::Free.
72 * @param size Number of elements in the array. If not a constant, this
73 * should be a int32_t. Note that this means this macro
74 * will not work if size >= 2^31.
75 * @param array The array to be freed.
76 * @param freeFunc The function or macro to be used to free it.
77 * For arrays of nsISupports (or any class derived
78 * from it), NS_IF_RELEASE (or NS_RELEASE) should be
79 * passed as freeFunc. For most (all?) other pointer
80 * types (including XPCOM strings and wstrings),
81 * nsMemory::Free should be used, since the
82 * shared-allocator (nsMemory) is what will have been
83 * used to allocate the memory.
85 #define NS_FREE_XPCOM_POINTER_ARRAY(size, array, freeFunc) \
86 PR_BEGIN_MACRO \
87 int32_t iter_ = int32_t(size); \
88 while (--iter_ >= 0) \
89 freeFunc((array)[iter_]); \
90 NS_Free((array)); \
91 PR_END_MACRO
93 // convenience macros for commonly used calls. mmmmm. syntactic sugar.
95 /**
96 * Macro to free arrays of non-refcounted objects allocated by the
97 * shared allocator (nsMemory) such as strings and wstrings. A
98 * convenience wrapper around NS_FREE_XPCOM_POINTER_ARRAY.
100 * @param size Number of elements in the array. If not a constant, this
101 * should be a int32_t. Note that this means this macro
102 * will not work if size >= 2^31.
103 * @param array The array to be freed.
105 #define NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(size, array) \
106 NS_FREE_XPCOM_POINTER_ARRAY((size), (array), NS_Free)
109 * Macro to free an array of pointers to nsISupports (or classes
110 * derived from it). A convenience wrapper around
111 * NS_FREE_XPCOM_POINTER_ARRAY.
113 * Note that if you know that none of your nsISupports pointers are
114 * going to be 0, you can gain a bit of speed by calling
115 * NS_FREE_XPCOM_POINTER_ARRAY directly and using NS_RELEASE as your
116 * free function.
118 * @param size Number of elements in the array. If not a constant, this
119 * should be a int32_t. Note that this means this macro
120 * will not work if size >= 2^31.
121 * @param array The array to be freed.
123 #define NS_FREE_XPCOM_ISUPPORTS_POINTER_ARRAY(size, array) \
124 NS_FREE_XPCOM_POINTER_ARRAY((size), (array), NS_IF_RELEASE)
127 * A macro, NS_ALIGNMENT_OF(t_) that determines the alignment
128 * requirements of a type.
130 namespace mozilla {
131 template<class T>
132 struct AlignmentTestStruct
134 char c;
135 T t;
139 #define NS_ALIGNMENT_OF(t_) \
140 (sizeof(mozilla::AlignmentTestStruct<t_>) - sizeof(t_))
143 * An enumeration type used to represent a method of assignment.
145 enum nsAssignmentType
147 NS_ASSIGNMENT_COPY, // copy by value
148 NS_ASSIGNMENT_DEPEND, // copy by reference
149 NS_ASSIGNMENT_ADOPT // copy by reference (take ownership of resource)
152 #endif // nsMemory_h__