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 | #ifndef _OBJECTMANAGER_H_ |
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28 | #define _OBJECTMANAGER_H_ |
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29 | |
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30 | #include <stdlib.h> // for size_t |
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31 | |
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32 | namespace HL { |
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33 | |
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34 | class EmptyHeap {}; |
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35 | |
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36 | // The default object manager class. |
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37 | |
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38 | |
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39 | template <class SuperHeap> |
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40 | class ObjectManagerBase : public SuperHeap { |
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41 | public: |
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42 | |
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43 | // Return the object's size. |
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44 | inline static size_t getSize (void * const ptr) { |
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45 | return getObject(ptr)->getSize(); |
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46 | } |
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47 | |
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48 | protected: |
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49 | |
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50 | //// accessors //// |
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51 | |
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52 | // Return the object's overhead (i.e., in the header). |
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53 | inline static size_t getOverhead (void * const) { |
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54 | return sizeof(AllocatedObject); |
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55 | } |
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56 | |
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57 | // Is this object free? |
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58 | inline static bool isFree (void * const ptr) { |
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59 | return getObject(ptr)->isFree(); |
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60 | } |
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61 | |
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62 | |
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63 | // Is the previous object free? |
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64 | inline static bool isPrevFree (void * const ptr) { |
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65 | return getObject(ptr)->isPrevFree(); |
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66 | } |
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67 | |
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68 | // Previous object |
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69 | inline static void * getPrev (void * const ptr) { |
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70 | return getObject(ptr)->getPrev(); |
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71 | } |
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72 | |
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73 | |
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74 | // Next object |
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75 | inline static void * getNext (void * const ptr) { |
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76 | return getObject(ptr)->getNext(); |
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77 | } |
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78 | |
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79 | |
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80 | //// mutators //// |
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81 | |
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82 | // Instantiate an object in a given space. |
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83 | inline static void * makeObject (void * buf, size_t prevSize, size_t sz) { |
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84 | AllocatedObject * p = new (buf) AllocatedObject (prevSize, sz); |
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85 | return (void *) (p + 1); |
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86 | } |
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87 | |
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88 | inline static size_t getPrevSize (void * const ptr) { |
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89 | return getObject(ptr)->getPrevSize(); |
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90 | } |
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91 | |
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92 | // Mark this item as free. |
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93 | inline static void markFree (void * ptr) { |
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94 | getObject(ptr)->markFree(); |
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95 | getObject(getNext(ptr))->markPrevFree(); |
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96 | } |
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97 | |
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98 | // Mark this item as in use. |
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99 | inline static void markInUse (void * ptr) { |
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100 | getObject(ptr)->markInUse(); |
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101 | getObject(getNext(ptr))->markPrevInUse(); |
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102 | } |
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103 | |
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104 | |
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105 | private: |
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106 | |
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107 | |
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108 | // Change the object's size. |
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109 | inline static void setSize (void * ptr, size_t sz) { |
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110 | getObject(ptr)->setSize (sz); |
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111 | } |
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112 | |
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113 | // Change the object's size. |
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114 | inline static void setPrevSize (void * ptr, size_t sz) { |
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115 | getObject(ptr)->setPrevSize (sz); |
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116 | } |
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117 | |
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118 | |
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119 | // All objects managed by this object manager |
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120 | // are prefaced by a header of type AllocatedObject, |
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121 | // which manages the size of the current & previous allocated objects. |
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122 | |
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123 | class AllocatedObject { |
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124 | friend class ObjectManagerBase<SuperHeap>; |
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125 | private: |
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126 | inline AllocatedObject (size_t prevSize, size_t sz) |
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127 | : _sz (sz) |
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128 | , _prevSize (prevSize) |
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129 | #if 0 //ndef NDEBUG |
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130 | , _magic ((double) MAGIC_NUMBER) |
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131 | #endif |
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132 | { |
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133 | // Set the prev size of the next object. |
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134 | ((AllocatedObject *) ((char *) (this + 1) + _sz))->setPrevSize (sz); |
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135 | assert (!isFree()); |
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136 | assert (!isPrevFree()); |
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137 | } |
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138 | |
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139 | inline size_t getSize (void) const { |
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140 | assert (isValid()); |
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141 | return _sz & ~FREE_BIT; |
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142 | } |
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143 | inline void setSize (size_t sz) { |
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144 | assert (sz > 0); |
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145 | assert (isValid()); |
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146 | _sz = sz; |
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147 | } |
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148 | inline bool isFree (void) const { |
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149 | assert (isValid()); |
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150 | return _sz & FREE_BIT; |
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151 | } |
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152 | inline bool isPrevFree (void) const { |
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153 | assert (isValid()); |
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154 | return _prevSize & FREE_BIT; |
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155 | } |
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156 | // Return the previous object (in address order). |
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157 | inline void * getPrev (void) const { |
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158 | assert (isValid()); |
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159 | return (void *) ((char *) this - getPrevSize()); |
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160 | } |
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161 | // Return the next object (in address order). |
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162 | inline void * getNext (void) const { |
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163 | assert (isValid()); |
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164 | return (void *) ((char *) (this+2) + getSize()); |
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165 | } |
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166 | inline size_t getPrevSize (void) const { |
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167 | assert (isValid()); |
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168 | return _prevSize & ~FREE_BIT; |
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169 | } |
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170 | inline void markFree (void) { |
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171 | assert (isValid()); |
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172 | markFree(_sz); |
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173 | } |
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174 | inline void markInUse (void) { |
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175 | assert (isValid()); |
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176 | markInUse(_sz); |
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177 | } |
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178 | inline void markPrevFree (void) { |
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179 | assert (isValid()); |
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180 | markFree(_prevSize); |
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181 | } |
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182 | inline void markPrevInUse (void) { |
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183 | assert (isValid()); |
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184 | markInUse(_prevSize); |
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185 | } |
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186 | inline void setPrevSize (size_t sz) { |
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187 | assert (sz > 0); |
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188 | assert (isValid()); |
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189 | _prevSize = sz; |
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190 | } |
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191 | private: |
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192 | enum { FREE_BIT = 1 }; |
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193 | enum { MAGIC_NUMBER = 0 }; |
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194 | |
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195 | int isValid (void) const { |
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196 | #if 0 // ndef NDEBUG |
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197 | return (_magic == (double) MAGIC_NUMBER); |
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198 | #else |
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199 | return 1; //((_sz & 6) == 0); |
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200 | #endif |
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201 | } |
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202 | |
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203 | inline static void markInUse (size_t& sz) { |
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204 | sz &= ~FREE_BIT; |
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205 | } |
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206 | |
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207 | inline static void markFree (size_t& sz) { |
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208 | sz |= FREE_BIT; |
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209 | } |
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210 | |
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211 | |
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212 | // The size of the previous object (that is, right behind this one). |
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213 | size_t _prevSize; |
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214 | |
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215 | // We steal the last bit of the size field |
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216 | // for free/in use. |
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217 | // If the last bit is 1, the object is free. |
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218 | // Otherwise, it's in use. |
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219 | size_t _sz; |
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220 | |
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221 | #if 0 //ndef NDEBUG |
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222 | double _magic; |
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223 | #endif |
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224 | }; |
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225 | |
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226 | protected: |
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227 | inline static AllocatedObject * getObject (void * const ptr) { |
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228 | return (AllocatedObject *) ptr - 1; |
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229 | } |
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230 | }; |
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231 | |
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232 | |
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233 | |
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234 | template <class SuperHeap> |
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235 | class ProvideObjectManager : public ObjectManagerBase<SuperHeap> { |
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236 | public: |
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237 | inline void * malloc (size_t sz) { |
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238 | assert (sz > 0); |
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239 | void * ptr = SuperHeap::malloc (sz + getOverhead(NULL)); |
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240 | if (ptr == NULL) |
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241 | return NULL; |
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242 | void * p = makeObject (ptr, getPrevSize((char *) ptr + getOverhead(NULL)), sz); |
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243 | markInUse (p); |
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244 | assert (getSize(p) >= sz); |
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245 | assert (getPrevSize(getNext(p)) == getSize(p)); |
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246 | return p; |
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247 | } |
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248 | |
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249 | inline void free (void * ptr) { |
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250 | int ps = getPrevSize(getNext(ptr)); |
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251 | int sz = getSize(ptr); |
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252 | assert (getPrevSize(getNext(ptr)) == getSize(ptr)); |
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253 | markFree (ptr); |
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254 | SuperHeap::free ((void *) getObject(ptr)); |
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255 | } |
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256 | }; |
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257 | |
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258 | |
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259 | template <class SuperHeap> |
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260 | class ObjectManager : public ObjectManagerBase<SuperHeap> { |
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261 | public: |
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262 | #if 1 |
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263 | inline void * malloc (size_t sz) { |
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264 | void * p = SuperHeap::malloc (sz); |
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265 | if (p != NULL) { |
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266 | assert (getSize(p) >= sz); |
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267 | //setPrevSize(getNext(p), getSize(p)); |
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268 | markInUse (p); |
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269 | } |
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270 | return p; |
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271 | } |
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272 | |
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273 | inline void free (void * ptr) { |
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274 | markFree (ptr); |
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275 | SuperHeap::free (ptr); |
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276 | } |
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277 | #endif |
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278 | }; |
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279 | |
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280 | |
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281 | |
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282 | class ObjectManagerWrapper { |
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283 | public: |
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284 | template <class S> |
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285 | class Manager : public ObjectManager<S> {}; |
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286 | }; |
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287 | |
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288 | |
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289 | class ProvideObjectManagerWrapper { |
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290 | public: |
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291 | template <class S> |
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292 | class Manager : public ProvideObjectManager<S> {}; |
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293 | }; |
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294 | |
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295 | template <class S> |
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296 | class NOP : public S {}; |
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297 | |
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298 | class NullObjectManagerWrapper { |
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299 | public: |
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300 | template <class S> |
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301 | class Manager : public NOP<S> {}; |
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302 | }; |
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303 | |
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304 | |
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305 | /* |
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306 | |
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307 | This ObjectManagerHeap is a tortuous work-around |
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308 | for a bug in Visual C++ 6.0 that finally allows us |
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309 | to pass ObjectManager wrappers as template arguments. |
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310 | |
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311 | This can go away once support is added for nested templates. |
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312 | |
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313 | Wrappers look like this: |
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314 | |
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315 | class Wrap1 { |
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316 | public: |
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317 | template <class S> |
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318 | class Manager : public ObjectManager<S> {}; |
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319 | }; |
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320 | |
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321 | */ |
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322 | |
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323 | |
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324 | #if __SVR4 |
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325 | template <class SuperHeap, class OMWrapper> |
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326 | class SelectObjectManagerHeap { |
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327 | public: |
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328 | class TheHeap : public OMWrapper::Manager<SuperHeap> {}; |
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329 | }; |
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330 | |
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331 | #else |
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332 | template <class SuperHeap, class OMWrapper> |
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333 | class SelectObjectManagerHeap { |
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334 | public: |
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335 | class ObjectManagerHeapProxy1 : public OMWrapper { |
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336 | public: |
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337 | template <class A> class Manager {}; |
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338 | }; |
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339 | |
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340 | class ObjectManagerHeapProxy2 : public ObjectManagerHeapProxy1 { |
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341 | private: |
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342 | typedef typename OMWrapper::Manager<SuperHeap> ManageFoo; |
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343 | public: |
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344 | class ManageMe : public ManageFoo {}; |
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345 | }; |
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346 | |
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347 | class TheHeap : public ObjectManagerHeapProxy2::ManageMe {}; |
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348 | }; |
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349 | #endif |
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350 | |
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351 | }; |
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352 | |
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353 | #endif |
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354 | |
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