1 | // -*- C++ -*- |
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2 | |
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3 | #ifndef _HOARDSUPERBLOCKHEADER_H_ |
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4 | #define _HOARDSUPERBLOCKHEADER_H_ |
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5 | |
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6 | #include <stdlib.h> |
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7 | |
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8 | namespace Hoard { |
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9 | |
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10 | template <class LockType, |
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11 | int SuperblockSize, |
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12 | typename HeapType> |
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13 | class HoardSuperblock; |
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14 | |
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15 | template <class LockType, |
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16 | int SuperblockSize, |
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17 | typename HeapType> |
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18 | class HoardSuperblockHeader { |
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19 | public: |
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20 | |
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21 | HoardSuperblockHeader (size_t sz, size_t bufferSize) |
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22 | : magicNumber (MAGIC_NUMBER), |
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23 | objectSize (sz), |
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24 | objectSizeIsPowerOfTwo (!(sz & (sz - 1)) && sz), |
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25 | totalObjects (bufferSize / sz), |
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26 | owner (NULL), |
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27 | prev (NULL), |
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28 | next (NULL), |
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29 | reapableObjects (bufferSize / sz), |
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30 | objectsFree (bufferSize / sz), |
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31 | start ((char *) (this + 1)), |
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32 | position (start) |
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33 | { |
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34 | } |
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35 | |
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36 | inline void * malloc (void) { |
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37 | assert (isValid()); |
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38 | void * ptr = reapAlloc(); |
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39 | if (!ptr) { |
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40 | ptr = freeListAlloc(); |
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41 | } |
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42 | assert ((size_t) ptr % sizeof(double) == 0); |
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43 | return ptr; |
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44 | } |
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45 | |
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46 | inline void free (void * ptr) { |
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47 | assert (isValid()); |
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48 | freeList.insert (reinterpret_cast<FreeSLList::Entry *>(ptr)); |
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49 | objectsFree++; |
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50 | if (objectsFree == totalObjects) { |
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51 | clear(); |
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52 | } |
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53 | } |
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54 | |
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55 | void clear (void) { |
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56 | assert (isValid()); |
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57 | // Clear out the freelist. |
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58 | freeList.clear(); |
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59 | // All the objects are now free. |
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60 | objectsFree = totalObjects; |
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61 | reapableObjects = totalObjects; |
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62 | position = start; |
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63 | } |
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64 | |
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65 | /// @brief Returns the actual start of the object. |
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66 | INLINE void * normalize (void * ptr) const { |
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67 | assert (isValid()); |
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68 | size_t offset = (size_t) ptr - (size_t) start; |
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69 | void * p; |
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70 | |
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71 | // Optimization note: the modulo operation (%) is *really* slow on |
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72 | // some architectures (notably x86-64). To reduce its overhead, we |
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73 | // optimize for the case when the size request is a power of two, |
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74 | // which is often enough to make a difference. |
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75 | |
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76 | if (objectSizeIsPowerOfTwo) { |
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77 | p = (void *) ((size_t) ptr - (offset & (objectSize - 1))); |
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78 | } else { |
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79 | p = (void *) ((size_t) ptr - (offset % objectSize)); |
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80 | } |
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81 | return p; |
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82 | } |
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83 | |
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84 | |
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85 | size_t getSize (void * ptr) const { |
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86 | assert (isValid()); |
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87 | size_t offset = (size_t) ptr - (size_t) start; |
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88 | size_t newSize; |
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89 | if (objectSizeIsPowerOfTwo) { |
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90 | newSize = objectSize - (offset & (objectSize - 1)); |
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91 | } else { |
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92 | newSize = objectSize - (offset % objectSize); |
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93 | } |
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94 | return newSize; |
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95 | } |
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96 | |
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97 | size_t getObjectSize (void) const { |
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98 | return objectSize; |
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99 | } |
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100 | |
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101 | int getTotalObjects (void) const { |
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102 | return totalObjects; |
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103 | } |
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104 | |
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105 | int getObjectsFree (void) const { |
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106 | return objectsFree; |
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107 | } |
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108 | |
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109 | HeapType * getOwner (void) const { |
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110 | return owner; |
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111 | } |
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112 | |
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113 | void setOwner (HeapType * o) { |
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114 | owner = o; |
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115 | } |
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116 | |
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117 | bool isValid (void) const { |
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118 | return (magicNumber == MAGIC_NUMBER); |
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119 | } |
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120 | |
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121 | HoardSuperblock<LockType, SuperblockSize, HeapType> * getNext (void) const { |
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122 | return next; |
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123 | } |
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124 | |
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125 | HoardSuperblock<LockType, SuperblockSize, HeapType> * getPrev (void) const { |
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126 | return prev; |
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127 | } |
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128 | |
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129 | void setNext (HoardSuperblock<LockType, SuperblockSize, HeapType> * n) { |
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130 | next = n; |
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131 | } |
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132 | |
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133 | void setPrev (HoardSuperblock<LockType, SuperblockSize, HeapType> * p) { |
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134 | prev = p; |
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135 | } |
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136 | |
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137 | void lock (void) { |
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138 | theLock.lock(); |
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139 | } |
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140 | |
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141 | void unlock (void) { |
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142 | theLock.unlock(); |
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143 | } |
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144 | |
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145 | private: |
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146 | |
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147 | MALLOC_FUNCTION INLINE void * reapAlloc (void) { |
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148 | assert (isValid()); |
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149 | assert (position); |
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150 | // Reap mode. |
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151 | if (reapableObjects > 0) { |
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152 | char * ptr = position; |
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153 | position = ptr + objectSize; |
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154 | reapableObjects--; |
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155 | objectsFree--; |
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156 | return ptr; |
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157 | } else { |
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158 | return NULL; |
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159 | } |
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160 | } |
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161 | |
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162 | MALLOC_FUNCTION INLINE void * freeListAlloc (void) { |
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163 | assert (isValid()); |
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164 | // Freelist mode. |
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165 | char * ptr = reinterpret_cast<char *>(freeList.get()); |
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166 | if (ptr) { |
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167 | assert (objectsFree >= 1); |
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168 | objectsFree--; |
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169 | } |
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170 | return ptr; |
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171 | } |
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172 | |
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173 | enum { MAGIC_NUMBER = 0xcafed00d }; |
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174 | |
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175 | const size_t magicNumber; |
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176 | |
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177 | /// The object size. |
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178 | const size_t objectSize; |
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179 | |
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180 | const bool objectSizeIsPowerOfTwo; |
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181 | |
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182 | /// Total objects in the superblock. |
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183 | const int totalObjects; |
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184 | |
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185 | /// The lock. |
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186 | LockType theLock; |
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187 | |
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188 | /// The owner of this superblock. |
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189 | HeapType * owner; |
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190 | |
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191 | /// The preceding superblock in a linked list. |
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192 | HoardSuperblock<LockType, SuperblockSize, HeapType> * prev; |
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193 | |
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194 | /// The succeeding superblock in a linked list. |
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195 | HoardSuperblock<LockType, SuperblockSize, HeapType> * next; |
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196 | |
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197 | /// The number of objects available to be 'reap'ed. |
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198 | int reapableObjects; |
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199 | |
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200 | /// The number of objects available for (re)use. |
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201 | int objectsFree; |
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202 | |
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203 | /// The start of reap allocation. |
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204 | char * start; |
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205 | |
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206 | /// The list of freed objects. |
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207 | FreeSLList freeList; |
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208 | |
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209 | /// The cursor into the buffer following the header. |
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210 | char * position; |
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211 | |
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212 | private: |
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213 | |
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214 | double _dummy; // for alignment |
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215 | }; |
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216 | |
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217 | }; |
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218 | |
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219 | #endif |
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