1 | /* -*- C++ -*- */ |
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2 | |
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3 | #ifndef _BATCHHEAP_H_ |
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4 | #define _BATCHHEAP_H_ |
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5 | |
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6 | #include <assert.h> |
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7 | |
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8 | |
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9 | template <class SuperHeap> |
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10 | class MultiMalloc : public SuperHeap { |
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11 | public: |
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12 | // Sets ptr to a list of up to num objects of size sz |
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13 | // and returns how many free objects ptr points to. |
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14 | int multimalloc (int num, size_t sz, void *& ptr) |
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15 | { |
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16 | int i = 0; |
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17 | ptr = (freeObject *) SuperHeap::malloc (sz); |
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18 | freeObject * p = (freeObject *) ptr; |
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19 | if (ptr != NULL) { |
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20 | for (i = 1; i < num; i++) { |
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21 | p->next = (freeObject *) SuperHeap::malloc (sz); |
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22 | if (p->next == NULL) |
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23 | break; |
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24 | p = p->next; |
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25 | } |
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26 | p->next = NULL; |
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27 | } |
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28 | return i; |
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29 | } |
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30 | |
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31 | // Frees all num items pointed to by ptr |
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32 | // and sets ptr to NULL. |
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33 | void multifree (int num, void *& ptr) |
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34 | { |
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35 | freeObject * p; |
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36 | freeObject * prev = (freeObject *) ptr; |
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37 | for (int i = 0; i < num; i++) { |
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38 | p = prev->next; |
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39 | SuperHeap::free (prev); |
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40 | prev = p; |
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41 | } |
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42 | ptr = NULL; |
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43 | } |
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44 | |
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45 | private: |
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46 | |
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47 | class freeObject { |
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48 | public: |
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49 | freeObject * next; |
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50 | }; |
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51 | |
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52 | |
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53 | }; |
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54 | |
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55 | |
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56 | template <int BatchNumber, class SuperHeap> |
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57 | class BatchHeap : public SuperHeap { |
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58 | public: |
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59 | |
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60 | BatchHeap (void) |
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61 | : nObjects (0) |
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62 | { |
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63 | freeList[0] = NULL; |
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64 | freeList[1] = NULL; |
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65 | } |
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66 | |
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67 | |
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68 | ~BatchHeap (void) { |
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69 | if (nObjects <= BatchNumber) { |
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70 | SuperHeap::multifree (nObjects, (void *&) freeList[0]); |
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71 | } else { |
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72 | SuperHeap::multifree (BatchNumber, (void *&) freeList[0]); |
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73 | SuperHeap::multifree (nObjects - BatchNumber, (void *&) freeList[1]); |
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74 | } |
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75 | } |
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76 | |
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77 | inline void * malloc (size_t sz) { |
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78 | if (nObjects == 0) { |
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79 | // Obtain BatchNumber objects if we're out. |
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80 | nObjects = SuperHeap::multimalloc (BatchNumber, sz, (void *&) freeList[0]); |
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81 | } |
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82 | assert (nObjects >= 1); |
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83 | freeObject * ptr; |
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84 | if (nObjects > BatchNumber) { |
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85 | freeObject *& head = freeList[1]; |
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86 | ptr = head; |
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87 | nObjects--; |
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88 | head = head->next; |
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89 | return (void *) ptr; |
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90 | } else { |
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91 | freeObject *& head = freeList[0]; |
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92 | ptr = head; |
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93 | nObjects--; |
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94 | head = head->next; |
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95 | return (void *) ptr; |
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96 | } |
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97 | } |
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98 | |
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99 | inline void free (void * ptr) { |
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100 | if (nObjects <= BatchNumber) { |
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101 | freeObject *& head = freeList[0]; |
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102 | ((freeObject *) ptr)->next = head; |
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103 | head = (freeObject *) ptr; |
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104 | } else { |
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105 | freeObject *& head = freeList[1]; |
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106 | ((freeObject *) ptr)->next = head; |
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107 | head = (freeObject *) ptr; |
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108 | } |
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109 | nObjects++; |
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110 | if (nObjects == 2 * BatchNumber) { |
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111 | // Free half of them. |
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112 | assert (freeList[1] != NULL); |
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113 | SuperHeap::multifree (BatchNumber, (void *&) freeList[1]); |
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114 | } |
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115 | } |
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116 | |
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117 | private: |
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118 | |
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119 | class freeObject { |
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120 | public: |
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121 | freeObject * next; |
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122 | }; |
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123 | |
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124 | int nObjects; |
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125 | |
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126 | // The first free list holds the first BatchNumber objects, |
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127 | // while the second free list holds the rest. |
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128 | freeObject * freeList[2]; |
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129 | }; |
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130 | |
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131 | #endif |
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