1 | // -*- C++ -*- |
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2 | |
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3 | /** |
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4 | * @file alignedmmap.h |
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5 | * @author Emery Berger <http://www.cs.umass.edu/~emery> |
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6 | */ |
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7 | |
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8 | |
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9 | #ifndef _ALIGNEDMMAP_H_ |
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10 | #define _ALIGNEDMMAP_H_ |
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11 | |
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12 | #include "sassert.h" |
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13 | #include "myhashmap.h" |
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14 | #include "freelistheap.h" |
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15 | #include "mmapwrapper.h" |
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16 | #include "bumpalloc.h" |
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17 | #include "exactlyone.h" |
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18 | #include "mmapalloc.h" |
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19 | |
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20 | using namespace std; |
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21 | using namespace HL; |
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22 | |
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23 | namespace Hoard { |
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24 | |
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25 | /** |
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26 | * @class AlignedMmapInstance |
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27 | * @brief Memory allocated from here is aligned with respect to Alignment. |
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28 | * @author Emery Berger <http://www.cs.umass.edu/~emery> |
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29 | */ |
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30 | |
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31 | |
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32 | template <size_t Alignment_> |
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33 | class AlignedMmapInstance { |
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34 | public: |
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35 | |
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36 | enum { Alignment = Alignment_ }; |
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37 | |
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38 | inline void * malloc (size_t sz) { |
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39 | |
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40 | // Round up sz to the nearest page. |
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41 | sz = (sz + HL::MmapWrapper::Size - 1) & ~(HL::MmapWrapper::Size - 1); |
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42 | |
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43 | // If the memory is already suitably aligned, just track size requests. |
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44 | if ((size_t) HL::MmapWrapper::Alignment % (size_t) Alignment == 0) { |
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45 | void * ptr = HL::MmapWrapper::map (sz); |
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46 | MyMap.set (ptr, sz); |
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47 | return ptr; |
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48 | } |
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49 | |
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50 | // Try a map call and hope that it's suitably aligned. If we get lucky, |
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51 | // we're done. |
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52 | |
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53 | char * ptr = reinterpret_cast<char *>(HL::MmapWrapper::map (sz)); |
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54 | |
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55 | if (ptr == align(ptr)) { |
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56 | // We're done. |
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57 | MyMap.set (ptr, sz); |
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58 | return ptr; |
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59 | } else { |
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60 | // Try again. |
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61 | HL::MmapWrapper::unmap ((void *) ptr, sz); |
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62 | } |
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63 | |
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64 | // We have to align it ourselves. We get memory from |
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65 | // mmap, align a pointer in the space, and free the space before |
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66 | // and after the aligned segment. |
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67 | |
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68 | ptr = reinterpret_cast<char *>(HL::MmapWrapper::map (sz + Alignment_)); |
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69 | |
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70 | if (ptr == NULL) { |
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71 | return NULL; |
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72 | } |
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73 | |
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74 | char * newptr = align (ptr); |
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75 | |
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76 | // Unmap the part before (prolog) and after. |
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77 | |
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78 | size_t prolog = (size_t) newptr - (size_t) ptr; |
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79 | |
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80 | if (prolog > 0) { |
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81 | // Get rid of the prolog. |
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82 | HL::MmapWrapper::unmap (ptr, prolog); |
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83 | } |
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84 | |
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85 | size_t epilog = Alignment_ - prolog; |
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86 | HL::MmapWrapper::unmap ((char *) newptr + sz, epilog); |
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87 | |
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88 | // Now record the size associated with this pointer. |
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89 | |
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90 | MyMap.set (newptr, sz); |
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91 | return newptr; |
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92 | } |
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93 | |
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94 | inline void free (void * ptr) { |
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95 | |
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96 | // Find the object. If we don't find it, we didn't allocate it. |
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97 | // For now, just ignore such an invalid free... |
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98 | |
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99 | size_t requestedSize = MyMap.get (ptr); |
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100 | |
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101 | if (requestedSize == 0) { |
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102 | return; |
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103 | } |
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104 | |
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105 | HL::MmapWrapper::unmap (ptr, requestedSize); |
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106 | |
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107 | // Finally, undo the mapping. |
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108 | MyMap.erase (ptr); |
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109 | |
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110 | assert (MyMap.get (ptr) == 0); |
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111 | } |
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112 | |
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113 | inline size_t getSize (void * ptr) { |
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114 | return MyMap.get (ptr); |
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115 | } |
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116 | |
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117 | |
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118 | private: |
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119 | |
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120 | /// Round a pointer up to the next Alignment-rounded chunk. |
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121 | inline static char * align (char * buf) { |
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122 | return (char *)(((size_t) buf + (Alignment_-1)) & ~(Alignment_-1)); |
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123 | } |
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124 | |
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125 | // Manage information in a map that uses a custom heap for |
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126 | // allocation. |
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127 | |
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128 | /// The key is an mmapped pointer. |
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129 | typedef void * keyType; |
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130 | |
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131 | /// The value is the requested size. |
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132 | typedef size_t valType; |
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133 | |
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134 | // The heap from which memory comes for the Map's purposes. |
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135 | // Objects come from chunks via mmap, and we manage these with a free list. |
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136 | class SourceHeap : public HL::FreelistHeap<BumpAlloc<65536, MmapAlloc> > { }; |
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137 | |
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138 | /// The map type, with all the pieces in place. |
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139 | typedef MyHashMap<keyType, valType, SourceHeap> mapType; |
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140 | |
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141 | /// The map that maintains the size of each mmapped chunk. |
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142 | mapType MyMap; |
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143 | |
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144 | }; |
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145 | |
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146 | |
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147 | /** |
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148 | * @class AlignedMmap |
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149 | * @brief Route requests to the one aligned mmap instance. |
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150 | * @author Emery Berger <http://www.cs.umass.edu/~emery> |
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151 | */ |
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152 | |
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153 | template <size_t Alignment_> |
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154 | class AlignedMmap : public ExactlyOne<AlignedMmapInstance<Alignment_> > { |
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155 | public: |
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156 | |
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157 | enum { Alignment = Alignment_ }; |
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158 | |
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159 | inline void * malloc (size_t sz) { |
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160 | return (*this)().malloc (sz); |
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161 | } |
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162 | inline void free (void * ptr) { |
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163 | return (*this)().free (ptr); |
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164 | } |
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165 | inline size_t getSize (void * ptr) const { |
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166 | return (*this)().getSize (ptr); |
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167 | } |
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168 | |
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169 | }; |
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170 | |
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171 | }; |
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172 | |
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173 | #endif |
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