1 | /* |
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2 | * xhtab.h - Remote access embedded hash table definition. |
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3 | * |
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4 | * Author Alain Greiner (2016,2017) |
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5 | * |
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6 | * Copyright (c) UPMC Sorbonne Universites |
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7 | * |
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8 | * This file is part of ALMOS-MKH. |
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9 | * |
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10 | * ALMOS-MKH is free software; you can redistribute it and/or modify it |
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11 | * under the terms of the GNU General Public License as published by |
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12 | * the Free Software Foundation; version 2.0 of the License. |
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13 | * |
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14 | * ALMOS-MKH is distributed in the hope that it will be useful, but |
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15 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
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16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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17 | * General Public License for more details. |
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18 | * |
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19 | * You should have received a copy of the GNU General Public License |
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20 | * along with ALMOS-MKH; if not, write to the Free Software Foundation, |
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21 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
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22 | */ |
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23 | |
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24 | #ifndef _XHTAB_H_ |
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25 | #define _XHTAB_H_ |
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26 | |
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27 | #include <kernel_config.h> |
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28 | #include <hal_kernel_types.h> |
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29 | #include <remote_rwlock.h> |
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30 | #include <xlist.h> |
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31 | |
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32 | |
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33 | /////////////////////////////////////////////////////////////////////////////////////////// |
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34 | // This file define a generic, embedded, remotely accessible hash table. |
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35 | // |
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36 | // It can be accessed by any thread, running in any cluster. |
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37 | // It is generic as it can be used to register various types of items. |
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38 | // The main goal is to speedup search by key in a large number of items of same type. |
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39 | // For this purpose the set of all registered items is split in several subsets. |
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40 | // Each subset is organised as an embedded double linked lists. |
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41 | // - an item is uniquely identified by a <key>, that is a single uint32_t value. |
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42 | // - From the <key> value, the hash table uses an item type specific xhtab_index() |
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43 | // function, to compute an <index> value, defining a subset of registered items. |
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44 | // - to discriminate between items that have the same <index>, the hash table makes |
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45 | // an associative search on the key in subset. |
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46 | // - Each registered item is a structure, that must contain an embedded xlist_entry, |
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47 | // that is part of the xlist implementing the subset. |
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48 | // |
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49 | // For all registered items, a total order is defined by the increasing index values, |
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50 | // and for each index value, by the position in the partial xlist. |
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51 | // This order is used by the two functions xhtab_get_first() and xhtab_get_next(), that |
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52 | // are used to scan all registered items. The two "current_index" and "current_xlist_xp" |
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53 | // fields in the hash table header register the current item during a scan. |
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54 | // |
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55 | // Implementation Note: |
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56 | // For each supported item type ***, you must define four item-type-specific |
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57 | // functions specified below, and you must update the xhtab_init() function |
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58 | // and the xhtab_item_type_t. |
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59 | /////////////////////////////////////////////////////////////////////////////////////////// |
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60 | |
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61 | #define XHASHTAB_SIZE 8 // number of subsets |
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62 | |
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63 | /****************************************************************************************** |
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64 | * This define the four item_type_specific function prototypes that must be defined |
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65 | * for each item type. |
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66 | *****************************************************************************************/ |
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67 | |
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68 | typedef bool_t (item_match_key_t) ( xptr_t item_xp , void * key ); |
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69 | typedef xptr_t (item_from_xlist_t) ( xptr_t xlist_xp ); |
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70 | typedef uint32_t (index_from_key_t) ( void * key ); |
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71 | typedef void (item_print_key_t) ( xptr_t item_xp ); |
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72 | |
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73 | /****************************************************************************************** |
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74 | * This define the supported item types. |
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75 | *****************************************************************************************/ |
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76 | |
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77 | typedef enum |
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78 | { |
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79 | XHTAB_DENTRY_TYPE = 0, /*! item is a vfs_dentry_t */ |
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80 | } |
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81 | xhtab_item_type_t; |
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82 | |
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83 | /****************************************************************************************** |
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84 | * This structure define the root of the remote accessible hash table. |
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85 | *****************************************************************************************/ |
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86 | |
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87 | typedef struct xhtab_s |
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88 | { |
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89 | xlist_entry_t roots[XHASHTAB_SIZE]; /*! array of roots of xlist */ |
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90 | index_from_key_t * index_from_key; /*! item specific function pointer */ |
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91 | item_match_key_t * item_match_key; /*! item specific function pointer */ |
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92 | item_from_xlist_t * item_from_xlist; /*! item specific function pointer */ |
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93 | item_print_key_t * item_print_key; /*! item specific function pointer */ |
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94 | uint32_t items; /*! number of registered items */ |
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95 | remote_rwlock_t lock; /*! lock protecting hash table accesses */ |
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96 | uint32_t current_index; /*! current item subset index */ |
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97 | xptr_t current_xlist_xp; /*! xptr on current item xlist entry */ |
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98 | } |
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99 | xhtab_t; |
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100 | |
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101 | /****************************************************************************************** |
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102 | * This function initializes an empty hash table (zero registered item). |
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103 | * The initialisation must be done by a thread running in cluster containing the table. |
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104 | ****************************************************************************************** |
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105 | * @ xhtab : local pointer on local xhtab to be initialized. |
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106 | * @ type : item type (see above). |
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107 | *****************************************************************************************/ |
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108 | void xhtab_init( xhtab_t * xhtab, |
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109 | xhtab_item_type_t type ); |
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110 | |
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111 | /****************************************************************************************** |
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112 | * This function safely register an item in the hash table, using the lock protecting it. |
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113 | ****************************************************************************************** |
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114 | * @ xhtab_xp : extended pointer on hash table. |
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115 | * @ key : local pointer on item identifier. |
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116 | * @ xlist_xp : extended pointer on xlist_entry_t embedded in item to be registered. |
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117 | * @ return 0 if success / return EINVAL if item already registered. |
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118 | *****************************************************************************************/ |
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119 | error_t xhtab_insert( xptr_t xhtab_xp, |
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120 | void * key, |
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121 | xptr_t xlist_xp ); |
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122 | |
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123 | /****************************************************************************************** |
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124 | * This function safely remove an item from the hash table, using the lock protecting it. |
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125 | ****************************************************************************************** |
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126 | * @ xhtab_xp : extended pointer on hash table. |
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127 | * @ key : local pointer on item identifier. |
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128 | * @ xlist_entry_xp : extended pointer on xlist_entry embedded in item to be removed. |
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129 | * @ return 0 if success / return EINVAL if item not found. |
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130 | *****************************************************************************************/ |
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131 | error_t xhtab_remove( xptr_t xhtab_xp, |
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132 | void * key, |
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133 | xptr_t xlist_entry_xp ); |
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134 | |
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135 | /****************************************************************************************** |
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136 | * This function search an item by its key in hash table, using the lock protecting it. |
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137 | ****************************************************************************************** |
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138 | * @ xhtab_xp : extended pointer on hash table. |
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139 | * @ key : local pointer on searched item identifier. |
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140 | * @ return extended pointer on the searched item if found / XPTR_NULL if not found. |
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141 | *****************************************************************************************/ |
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142 | xptr_t xhtab_lookup( xptr_t xhtab_xp, |
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143 | void * key ); |
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144 | |
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145 | /****************************************************************************************** |
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146 | * This blocking function takes the lock protecting exclusive access to the hash table. |
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147 | * It should be called before the xhtab_get_first() & xhtab_get_next() functions. |
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148 | ****************************************************************************************** |
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149 | * @ xhtab_xp : extended pointer on hash table. |
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150 | *****************************************************************************************/ |
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151 | void xhtab_read_lock( xptr_t xhtab_xp ); |
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152 | |
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153 | /****************************************************************************************** |
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154 | * This function releases the lock protecting exclusive access to the hash table. |
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155 | * It should be called after the xhtab_get_first() & xhtab_get_next() functions. |
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156 | ****************************************************************************************** |
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157 | * @ xhtab_xp : extended pointer on hash table. |
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158 | *****************************************************************************************/ |
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159 | void xhtab_read_unlock( xptr_t xhtab_xp ); |
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160 | |
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161 | /****************************************************************************************** |
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162 | * This function returns an extended pointer on the first item registered in hash table, |
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163 | * and register this pointer in the hash table header. |
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164 | * The lock protecting the hash table must have been previously taken by the caller. |
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165 | ****************************************************************************************** |
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166 | * @ xhtab_xp : extended pointer on hash table. |
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167 | * @ return extended pointer on item if success / XPTR_NULL if not found. |
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168 | *****************************************************************************************/ |
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169 | xptr_t xhtab_get_first( xptr_t xhtab_xp ); |
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170 | |
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171 | /****************************************************************************************** |
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172 | * This function returns an extended pointer on item following the currently pointed |
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173 | * item in the hash table header. |
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174 | * The lock protecting the hash table must have been previously taken by the caller. |
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175 | ****************************************************************************************** |
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176 | * @ xhtab_xp : extended pointer on hash table. |
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177 | * @ return extended pointer on item if success / XPTR_NULL if not found. |
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178 | *****************************************************************************************/ |
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179 | xptr_t xhtab_get_next( xptr_t xhtab_xp ); |
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180 | |
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181 | /****************************************************************************************** |
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182 | * This function displays the full content of an xhtab. |
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183 | ****************************************************************************************** |
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184 | * @ xhtab_xp : extended pointer on hash table. |
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185 | *****************************************************************************************/ |
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186 | void xhtab_display( xptr_t xhtab_xp ); |
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187 | |
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188 | #endif /* _XHTAB_H_ */ |
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