1 | // -*- C++ -*- |
---|
2 | |
---|
3 | /** |
---|
4 | * |
---|
5 | * @class ThreadLocalAllocationBuffer |
---|
6 | * @author Emery Berger <http://www.cs.umass.edu/~emery> |
---|
7 | * @brief An allocator, meant to be used for thread-local allocation. |
---|
8 | */ |
---|
9 | |
---|
10 | #include "dllist.h" |
---|
11 | #include "array.h" |
---|
12 | |
---|
13 | namespace Hoard { |
---|
14 | |
---|
15 | template <int NumBins, |
---|
16 | int (*getSizeClass) (size_t), |
---|
17 | size_t (*getClassSize) (const int), |
---|
18 | int LargestObject, |
---|
19 | int LocalHeapThreshold, |
---|
20 | class SuperblockType, |
---|
21 | int SuperblockSize, |
---|
22 | class ParentHeap> |
---|
23 | |
---|
24 | class ThreadLocalAllocationBuffer { |
---|
25 | |
---|
26 | public: |
---|
27 | |
---|
28 | ThreadLocalAllocationBuffer (ParentHeap * parent) |
---|
29 | : _parentHeap (parent), |
---|
30 | _localHeapBytes (0) |
---|
31 | { |
---|
32 | } |
---|
33 | |
---|
34 | ~ThreadLocalAllocationBuffer (void) { |
---|
35 | clear(); |
---|
36 | } |
---|
37 | |
---|
38 | inline static size_t getSize (void * ptr) { |
---|
39 | return getSuperblock(ptr)->getSize (ptr); |
---|
40 | } |
---|
41 | |
---|
42 | inline void * malloc (size_t sz) { |
---|
43 | #if 1 |
---|
44 | if (sz < 2 * sizeof(size_t)) { |
---|
45 | sz = 2 * sizeof(size_t); |
---|
46 | } |
---|
47 | sz = align (sz); |
---|
48 | #endif |
---|
49 | // Get memory from the local heap, |
---|
50 | // and deduct that amount from the local heap bytes counter. |
---|
51 | if (sz <= LargestObject) { |
---|
52 | int c = getSizeClass (sz); |
---|
53 | void * ptr = _localHeap(c).get(); |
---|
54 | if (ptr) { |
---|
55 | _localHeapBytes -= sz; |
---|
56 | assert (getSize(ptr) >= sz); |
---|
57 | return ptr; |
---|
58 | } |
---|
59 | } |
---|
60 | |
---|
61 | // No more local memory (for this size, at least). |
---|
62 | // Now get the memory from our parent. |
---|
63 | void * ptr = _parentHeap->malloc (sz); |
---|
64 | return ptr; |
---|
65 | } |
---|
66 | |
---|
67 | |
---|
68 | inline void free (void * ptr) { |
---|
69 | if (!ptr) { |
---|
70 | return; |
---|
71 | } |
---|
72 | const SuperblockType * s = getSuperblock (ptr); |
---|
73 | // If this isn't a valid superblock, just return. |
---|
74 | |
---|
75 | if (s->isValidSuperblock()) { |
---|
76 | |
---|
77 | ptr = s->normalize (ptr); |
---|
78 | const size_t sz = s->getObjectSize (); |
---|
79 | |
---|
80 | if (sz <= LargestObject) { |
---|
81 | // Free small objects locally. |
---|
82 | |
---|
83 | assert (getSize(ptr) >= sizeof(HL::DLList::Entry *)); |
---|
84 | int c = getSizeClass (sz); |
---|
85 | |
---|
86 | _localHeap(c).insert ((HL::DLList::Entry *) ptr); |
---|
87 | _localHeapBytes += sz; |
---|
88 | |
---|
89 | // If we have too much memory stored locally, |
---|
90 | // give it all back. |
---|
91 | |
---|
92 | if (_localHeapBytes > LocalHeapThreshold) { |
---|
93 | clear(); |
---|
94 | } |
---|
95 | |
---|
96 | } else { |
---|
97 | // Free it to the parent. |
---|
98 | _parentHeap->free (ptr); |
---|
99 | } |
---|
100 | |
---|
101 | } else { |
---|
102 | #if 0 |
---|
103 | char buf[255]; |
---|
104 | sprintf (buf, "illegal ptr = %x.\n", ptr); |
---|
105 | printf (buf); |
---|
106 | #endif |
---|
107 | } |
---|
108 | } |
---|
109 | |
---|
110 | void clear (void) { |
---|
111 | // Free every object to the 'parent' heap. |
---|
112 | for (int i = NumBins-1; i >= 0; i--) { |
---|
113 | while (!_localHeap(i).isEmpty()) { |
---|
114 | HL::DLList::Entry * e = _localHeap(i).get(); |
---|
115 | _parentHeap->free (e); |
---|
116 | } |
---|
117 | } |
---|
118 | _localHeapBytes = 0; |
---|
119 | } |
---|
120 | |
---|
121 | static inline SuperblockType * getSuperblock (void * ptr) { |
---|
122 | return SuperblockType::getSuperblock (ptr); |
---|
123 | } |
---|
124 | |
---|
125 | private: |
---|
126 | |
---|
127 | inline static size_t align (size_t sz) { |
---|
128 | return (sz + (sizeof(double) - 1)) & ~(sizeof(double) - 1); |
---|
129 | } |
---|
130 | |
---|
131 | |
---|
132 | // Disable assignment and copying. |
---|
133 | |
---|
134 | ThreadLocalAllocationBuffer (const ThreadLocalAllocationBuffer&); |
---|
135 | ThreadLocalAllocationBuffer& operator=(const ThreadLocalAllocationBuffer&); |
---|
136 | |
---|
137 | /// This heap's 'parent' (where to go for more memory). |
---|
138 | ParentHeap * _parentHeap; |
---|
139 | |
---|
140 | /// The number of bytes we currently have on this thread. |
---|
141 | int _localHeapBytes; |
---|
142 | |
---|
143 | /// The local heap itself. |
---|
144 | Array<NumBins, HL::DLList> _localHeap; |
---|
145 | |
---|
146 | }; |
---|
147 | |
---|
148 | } |
---|