1 | /* -*- C++ -*- */ |
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2 | |
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3 | /* |
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4 | |
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5 | Heap Layers: An Extensible Memory Allocation Infrastructure |
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6 | |
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7 | Copyright (C) 2000-2003 by Emery Berger |
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8 | http://www.cs.umass.edu/~emery |
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9 | emery@cs.umass.edu |
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10 | |
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11 | This program is free software; you can redistribute it and/or modify |
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12 | it under the terms of the GNU General Public License as published by |
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13 | the Free Software Foundation; either version 2 of the License, or |
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14 | (at your option) any later version. |
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15 | |
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16 | This program is distributed in the hope that it will be useful, |
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17 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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18 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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19 | GNU General Public License for more details. |
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20 | |
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21 | You should have received a copy of the GNU General Public License |
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22 | along with this program; if not, write to the Free Software |
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23 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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24 | |
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25 | */ |
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26 | |
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27 | /** |
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28 | * @file coalesceableheap.h |
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29 | * @brief Coalescing support, via RequireCoalesceable and CoalesceableHeap. |
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30 | * @author Emery Berger |
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31 | */ |
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32 | |
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33 | #ifndef _COALESCEABLEHEAP_H_ |
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34 | #define _COALESCEABLEHEAP_H_ |
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35 | |
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36 | #include <assert.h> |
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37 | |
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38 | #define MULTIPLE_HEAP_SUPPORT 0 |
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39 | |
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40 | /** |
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41 | * @class RequireCoalesceable |
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42 | * @brief Provides support for coalescing objects. |
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43 | */ |
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44 | |
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45 | namespace HL { |
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46 | |
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47 | template <class SuperHeap> |
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48 | class RequireCoalesceable : public SuperHeap { |
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49 | public: |
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50 | |
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51 | // Some thin wrappers over Header methods. |
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52 | inline static int getHeap (void * ptr) { return Header::getHeader(ptr)->getHeap(); } |
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53 | inline static void setHeap (void * ptr, int h) { Header::getHeader(ptr)->setHeap(h); } |
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54 | inline static int getPrevHeap (void * ptr) { return Header::getHeader(ptr)->getPrevHeap(); } |
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55 | inline static void setPrevHeap (void * ptr, int h) { Header::getHeader(ptr)->setPrevHeap(h); } |
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56 | |
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57 | inline static size_t getSize (const void * ptr) { return Header::getHeader(ptr)->getSize(); } |
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58 | |
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59 | inline static void setSize (void * ptr, const size_t sz) { Header::getHeader(ptr)->setSize(sz); } |
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60 | inline static size_t getPrevSize (void * ptr) { return Header::getHeader(ptr)->getPrevSize(); } |
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61 | inline static void setPrevSize (void * ptr, const size_t sz) { Header::getHeader(ptr)->setPrevSize(sz); } |
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62 | inline static void markFree (void * ptr) { Header::getHeader(ptr)->markFree(); } |
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63 | inline static void markInUse (void * ptr) { Header::getHeader(ptr)->markInUse(); } |
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64 | inline static void markPrevInUse (void * ptr) { Header::getHeader(ptr)->markPrevInUse(); } |
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65 | inline static void markMmapped (void * ptr) { Header::getHeader(ptr)->markMmapped(); } |
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66 | inline static int isFree (void * ptr) { return Header::getHeader(ptr)->isFree(); } |
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67 | inline static int isPrevFree (void * ptr) { return Header::getHeader(ptr)->isPrevFree(); } |
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68 | inline static int isMmapped (void * ptr) { return Header::getHeader(ptr)->isMmapped(); } |
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69 | inline static void * getNext (const void * ptr) { return Header::getHeader(ptr)->getNext(); } |
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70 | inline static void * getPrev (const void * ptr) { return Header::getHeader(ptr)->getPrev(); } |
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71 | |
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72 | // The Header for every object, allocated or freed. |
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73 | class Header { |
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74 | friend class RequireCoalesceable<SuperHeap>; |
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75 | public: |
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76 | |
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77 | // |
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78 | // Initialize a new object in a given buffer, with a previous & current object size. |
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79 | // Returns the start of the object (i.e., just past the header). |
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80 | // |
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81 | inline static void * makeObject (void * buf, const size_t prevsz, const size_t sz) { |
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82 | *((Header *) buf) = Header (prevsz, sz); |
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83 | Header * nextHeader = (Header *) ((char *) ((Header *) buf + 1) + sz); |
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84 | // Header * nextHeader = h->getNextHeader(); |
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85 | // nextHeader->markPrevInUse(); |
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86 | nextHeader->setPrevSize (sz); |
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87 | // return Header::getObject (h); |
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88 | return ((Header *) buf + 1); |
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89 | } |
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90 | |
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91 | |
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92 | inline void sanityCheck (void) { |
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93 | #ifndef NDEBUG |
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94 | int headerSize = sizeof(Header); |
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95 | assert (headerSize <= sizeof(double)); |
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96 | assert (getSize() == getNextHeader()->getPrevSize()); |
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97 | assert (isFree() == getNextHeader()->isPrevFree()); |
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98 | assert (getNextHeader()->getPrev() == getObject(this)); |
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99 | #if 0 |
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100 | if (isPrevFree()) { |
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101 | assert (getPrevSize() == getHeader(getPrev())->getSize()); |
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102 | } |
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103 | #endif |
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104 | #endif |
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105 | } |
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106 | |
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107 | // Get the header for a given object. |
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108 | inline static Header * getHeader (const void * ptr) { return ((Header *) ptr - 1); } |
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109 | |
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110 | // Get the object for a given header. |
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111 | inline static void * getObject (const Header * hd) { return (void *) (hd + 1); } |
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112 | |
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113 | inline void setSize (const size_t sz) { _size = sz; } |
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114 | inline void setPrevSize (const size_t sz){ _prevSize = sz; } |
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115 | |
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116 | // private: |
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117 | inline size_t getPrevSize (void) const { return _prevSize; } |
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118 | |
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119 | inline void markFree (void) { |
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120 | // printf ("markFree\n"); |
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121 | getNextHeader()->markPrevFree(); |
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122 | } |
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123 | inline void markInUse (void) { |
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124 | // printf ("markInUse\n"); |
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125 | getNextHeader()->markPrevInUse(); |
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126 | } |
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127 | inline void markMmapped (void) { _isMmapped = IS_MMAPPED; } |
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128 | inline void markNotMmapped (void) { _isMmapped = NOT_MMAPPED; } |
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129 | inline int isFree (void) const { |
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130 | // printf ("isFree\n"); |
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131 | return getNextHeader()->isPrevFree(); |
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132 | } |
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133 | inline int isNextFree (void) const { |
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134 | // printf ("isNextFree\n"); |
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135 | return getNextHeader()->getNextHeader()->isPrevFree(); |
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136 | } |
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137 | inline int isMmapped (void) const { return (_isMmapped != NOT_MMAPPED); } |
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138 | inline void * getPrev (void) const { |
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139 | // fprintf (stderr, "coalesceableheap.h: %x, %d\n", this, getPrevSize()); |
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140 | return ((char *) this) - getPrevSize(); |
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141 | } |
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142 | inline void * getNext (void) const { |
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143 | // printf ("getNext\n"); |
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144 | return ((char *) (this + 2)) + getSize(); |
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145 | } |
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146 | |
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147 | inline void markPrevFree (void) { _prevStatus = PREV_FREE; } |
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148 | inline void markPrevInUse (void) { _prevStatus = PREV_INUSE; } |
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149 | inline int isPrevFree (void) const { return (_prevStatus != PREV_INUSE); } |
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150 | inline size_t getSize (void) const { return _size; } |
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151 | |
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152 | #if MULTIPLE_HEAP_SUPPORT |
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153 | inline int getHeap (void) const { return _currHeap; } |
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154 | inline void setHeap (int h) { _currHeap = h; } |
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155 | inline int getPrevHeap (void) const { return _prevHeap; } |
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156 | inline void setPrevHeap (int h) { _prevHeap = h; } |
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157 | #else |
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158 | inline int getHeap (void) const { return 0; } |
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159 | inline void setHeap (int) { } |
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160 | inline int getPrevHeap (void) const { return 0; } |
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161 | inline void setPrevHeap (int) { } |
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162 | #endif |
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163 | |
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164 | |
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165 | private: |
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166 | |
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167 | explicit inline Header (void) {} |
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168 | explicit inline Header (const size_t prevsz, const size_t sz) |
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169 | : |
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170 | _prevSize (prevsz), |
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171 | _size (sz), |
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172 | // Assume that objects are NOT mmapped. |
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173 | _isMmapped (NOT_MMAPPED) |
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174 | #if MULTIPLE_HEAP_SUPPORT |
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175 | , _prevHeap (0), |
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176 | _currHeap (0) |
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177 | #endif |
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178 | { |
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179 | assert (sizeof(Header) <= sizeof(double)); |
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180 | } |
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181 | |
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182 | inline Header * getNextHeader (void) const { |
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183 | // printf ("H\n"); |
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184 | return ((Header *) ((char *) (this + 1) + getSize())); |
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185 | } |
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186 | |
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187 | #if !(MULTIPLE_HEAP_SUPPORT) // original |
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188 | |
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189 | // Is the previous object free or in use? |
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190 | enum { PREV_INUSE = 0, PREV_FREE = 1 }; |
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191 | unsigned int _prevStatus : 1; |
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192 | |
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193 | // Is the current object mmapped? |
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194 | enum { NOT_MMAPPED = 0, IS_MMAPPED = 1 }; |
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195 | unsigned int _isMmapped : 1; |
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196 | |
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197 | // The size of the previous object. |
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198 | enum { NUM_BITS_STOLEN_FROM_PREVSIZE = 2 }; |
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199 | size_t _prevSize : sizeof(size_t) * 8 - NUM_BITS_STOLEN_FROM_PREVSIZE; |
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200 | |
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201 | // The size of the current object. |
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202 | enum { NUM_BITS_STOLEN_FROM_SIZE = 0 }; |
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203 | size_t _size; // : sizeof(size_t) * 8 - NUM_BITS_STOLEN_FROM_SIZE; |
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204 | |
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205 | |
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206 | #else // new support for scalability... |
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207 | |
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208 | // Support for 2^5 = 32 heaps. |
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209 | enum { NUM_BITS_FOR_HEAP = 5 }; |
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210 | |
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211 | enum { NUM_BITS_STOLEN_FROM_SIZE = NUM_BITS_FOR_HEAP + 1 }; // 1 for isMmapped |
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212 | enum { NUM_BITS_STOLEN_FROM_PREVSIZE = NUM_BITS_FOR_HEAP + 1 }; // 1 for isPrevFree |
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213 | |
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214 | // Max object size. |
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215 | enum { MAX_OBJECT_SIZE = 1 << (sizeof(size_t) * 8 - NUM_BITS_STOLEN_FROM_SIZE) }; |
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216 | |
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217 | //// word 1 //// |
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218 | |
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219 | // The size of the previous object. |
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220 | size_t _prevSize : sizeof(size_t) * 8 - NUM_BITS_STOLEN_FROM_PREVSIZE; |
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221 | |
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222 | // What's the previous heap? |
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223 | unsigned int _prevHeap : NUM_BITS_FOR_HEAP; |
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224 | |
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225 | // Is the previous object free or in use? |
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226 | enum { PREV_FREE = 0, PREV_INUSE = 1 }; |
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227 | unsigned int _prevStatus : 1; |
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228 | |
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229 | //// word 2 //// |
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230 | |
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231 | // The size of the current object. |
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232 | size_t _size : sizeof(size_t) * 8 - NUM_BITS_STOLEN_FROM_SIZE; |
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233 | |
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234 | // What's the current heap? |
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235 | unsigned int _currHeap : NUM_BITS_FOR_HEAP; |
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236 | |
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237 | // Is the current object mmapped? |
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238 | enum { NOT_MMAPPED = 0, IS_MMAPPED = 1 }; |
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239 | unsigned int _isMmapped : 1; |
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240 | |
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241 | #endif |
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242 | }; |
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243 | |
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244 | inline static void * makeObject (void * buf, const size_t prevsz, const size_t sz) { |
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245 | return Header::makeObject (buf, prevsz, sz); |
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246 | } |
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247 | |
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248 | inline static Header * getHeader (const void * ptr) { |
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249 | return Header::getHeader (ptr); |
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250 | } |
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251 | |
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252 | }; |
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253 | |
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254 | |
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255 | /** |
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256 | * @class CoalesceableHeap |
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257 | * @brief Manages coalesceable memory. |
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258 | */ |
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259 | |
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260 | template <class SuperHeap> |
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261 | class CoalesceableHeap : public RequireCoalesceable<SuperHeap> { |
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262 | public: |
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263 | |
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264 | typedef typename RequireCoalesceable<SuperHeap>::Header Header; |
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265 | |
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266 | inline CoalesceableHeap (void) |
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267 | { } |
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268 | |
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269 | inline void * malloc (const size_t sz) { |
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270 | void * buf = SuperHeap::malloc (sz + sizeof(Header)); |
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271 | if (buf) { |
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272 | Header * header = (Header *) buf; |
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273 | |
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274 | // |
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275 | // Record the size of this object in the current header |
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276 | // and the next. |
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277 | // |
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278 | |
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279 | header->setSize (sz); |
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280 | |
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281 | // Below was: |
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282 | // Header * nextHeader = Header::getHeader (header->getNext()); |
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283 | Header * nextHeader = (Header *) ((char *) (header + 1) + sz); |
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284 | |
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285 | nextHeader->setPrevSize (sz); |
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286 | |
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287 | #if 0 |
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288 | // |
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289 | // As long as the source of this memory |
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290 | // is always zeroed, these assertions will hold. |
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291 | // The easiest way to do this is to use a ZeroHeap. |
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292 | // |
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293 | assert (header->isMmapped() == FALSE); |
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294 | assert (nextHeader->getSize() == 0); |
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295 | assert (!nextHeader->isFree()); |
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296 | assert (!nextHeader->isPrevFree()); |
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297 | |
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298 | #else |
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299 | |
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300 | // If the memory is not zeroed, we need this section of code. |
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301 | |
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302 | // |
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303 | // Assume that everything allocated is NOT mmapped. |
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304 | // It is the responsibility of a child layer |
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305 | // to mark mmapped objects as such. |
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306 | // |
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307 | |
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308 | header->markNotMmapped (); |
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309 | |
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310 | nextHeader->setSize (0); |
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311 | |
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312 | // |
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313 | // Mark the subsequent "object" as in use in order to prevent |
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314 | // accidental coalescing. |
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315 | // |
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316 | |
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317 | // (nextHeader + 1)->markPrevInUse(); |
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318 | nextHeader->markInUse (); |
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319 | #endif |
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320 | |
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321 | // Below was: |
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322 | // return Header::getObject (header); |
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323 | return (header + 1); |
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324 | } |
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325 | return NULL; |
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326 | } |
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327 | |
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328 | inline void free (void * ptr) { |
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329 | assert (SuperHeap::isFree(ptr)); |
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330 | SuperHeap::free ((Header *) ptr - 1); |
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331 | } |
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332 | |
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333 | |
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334 | }; |
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335 | |
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336 | }; |
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337 | |
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338 | #endif // _COALESCEABLEHEAP_H_ |
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339 | |
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