Programming Languages Research Group: Git - IRC.git/blob

   1 #include "mlookup.h"
   2
   3 mhashtable_t mlookup;   //Global hash table
   4
   5 // Creates a machine lookup table with size =" size"
   6 unsigned int mhashCreate(unsigned int size, float loadfactor)  {
   7         mhashlistnode_t *nodes;
   8         // Allocate space for the hash table
   9         if((nodes = calloc(size, sizeof(mhashlistnode_t))) == NULL) {
  10                 printf("Calloc error %s %d\n", __FILE__, __LINE__);
  11                 return 1;
  12         }
  13
  14         mlookup.table = nodes;
  15         mlookup.size = size;
  16         mlookup.numelements = 0; // Initial number of elements in the hash
  17         mlookup.loadfactor = loadfactor;
  18         //Initialize the pthread_mutex variable
  19         pthread_mutex_init(&mlookup.locktable, NULL);
  20         return 0;
  21 }
  22
  23 // Assign to keys to bins inside hash table
  24 unsigned int mhashFunction(unsigned int key) {
  25         return( key % (mlookup.size));
  26 }
  27
  28 // Insert value and key mapping into the hash table
  29 unsigned int mhashInsert(unsigned int key, void *val) {
  30         unsigned int newsize;
  31         int index;
  32         mhashlistnode_t *ptr, *node;
  33
  34         if (mlookup.numelements > (mlookup.loadfactor * mlookup.size)) {
  35                 //Resize Table
  36                 newsize = 2 * mlookup.size + 1;
  37                 pthread_mutex_lock(&mlookup.locktable);
  38                 mhashResize(newsize);
  39                 pthread_mutex_unlock(&mlookup.locktable);
  40         }
  41         ptr = mlookup.table;
  42         mlookup.numelements++;
  43
  44         index = mhashFunction(key);
  45 #ifdef DEBUG
  46         printf("DEBUG -> index = %d, key = %d, val = %x\n", index, key, val);
  47 #endif
  48         pthread_mutex_lock(&mlookup.locktable);
  49         if(ptr[index].next == NULL && ptr[index].key == 0) {    // Insert at the first position in the hashtable
  50                 ptr[index].key = key;
  51                 ptr[index].val = val;
  52         } else {                        // Insert in the beginning of linked list
  53                 if ((node = calloc(1, sizeof(mhashlistnode_t))) == NULL) {
  54                         printf("Calloc error %s, %d\n", __FILE__, __LINE__);
  55                         pthread_mutex_unlock(&mlookup.locktable);
  56                         return 1;
  57                 }
  58                 node->key = key;
  59                 node->val = val;
  60                 node->next = ptr[index].next;
  61                 ptr[index].next = node;
  62         }
  63         pthread_mutex_unlock(&mlookup.locktable);
  64         return 0;
  65 }
  66
  67 // Return val for a given key in the hash table
  68 void *mhashSearch(unsigned int key) {
  69         int index;
  70         mhashlistnode_t *ptr, *node;
  71
  72         ptr = mlookup.table;    // Address of the beginning of hash table
  73         index = mhashFunction(key);
  74         node = &ptr[index];
  75         pthread_mutex_lock(&mlookup.locktable);
  76         while(node != NULL) {
  77                 if(node->key == key) {
  78                         pthread_mutex_unlock(&mlookup.locktable);
  79                         return node->val;
  80                 }
  81                 node = node->next;
  82         }
  83         pthread_mutex_unlock(&mlookup.locktable);
  84         return NULL;
  85 }
  86
  87 // Remove an entry from the hash table
  88 unsigned int mhashRemove(unsigned int key) {
  89         int index;
  90         mhashlistnode_t *curr, *prev;
  91         mhashlistnode_t *ptr, *node;
  92
  93         ptr = mlookup.table;
  94         index = mhashFunction(key);
  95         curr = &ptr[index];
  96
  97         pthread_mutex_lock(&mlookup.locktable);
  98         for (; curr != NULL; curr = curr->next) {
  99                 if (curr->key == key) {         // Find a match in the hash table
 100                         mlookup.numelements--;  // Decrement the number of elements in the global hashtable
 101                         if ((curr == &ptr[index]) && (curr->next == NULL))  { // Delete the first item inside the hashtable with no linked list of mhashlistnode_t
 102                                 curr->key = 0;
 103                                 curr->val = NULL;
 104                         } else if ((curr == &ptr[index]) && (curr->next != NULL)) { //Delete the first item with a linked list of mhashlistnode_t  connected
 105                                 curr->key = curr->next->key;
 106                                 curr->val = curr->next->val;
 107                                 node = curr->next;
 108                                 curr->next = curr->next->next;
 109                                 free(node);
 110                         } else {                                                // Regular delete from linked listed
 111                                 prev->next = curr->next;
 112                                 free(curr);
 113                         }
 114                         pthread_mutex_unlock(&mlookup.locktable);
 115                         return 0;
 116                 }
 117                 prev = curr;
 118         }
 119         pthread_mutex_unlock(&mlookup.locktable);
 120         return 1;
 121 }
 122
 123 // Resize table
 124 unsigned int mhashResize(unsigned int newsize) {
 125         mhashlistnode_t *node, *ptr, *curr, *next;      // curr and next keep track of the current and the next mhashlistnodes in a linked list
 126         unsigned int oldsize;
 127         int isfirst;    // Keeps track of the first element in the mhashlistnode_t for each bin in hashtable
 128         int i,index;
 129         mhashlistnode_t *newnode;
 130
 131         ptr = mlookup.table;
 132         oldsize = mlookup.size;
 133
 134         if((node = calloc(newsize, sizeof(mhashlistnode_t))) == NULL) {
 135                 printf("Calloc error %s %d\n", __FILE__, __LINE__);
 136                 return 1;
 137         }
 138
 139         mlookup.table = node;           //Update the global hashtable upon resize()
 140         mlookup.size = newsize;
 141         mlookup.numelements = 0;
 142
 143         for(i = 0; i < oldsize; i++) {                  //Outer loop for each bin in hash table
 144                 curr = &ptr[i];
 145                 isfirst = 1;
 146                 while (curr != NULL) {                  //Inner loop to go through linked lists
 147                         if (curr->key == 0) {           //Exit inner loop if there the first element for a given bin/index is NULL
 148                                 break;                  //key = val =0 for element if not present within the hash table
 149                         }
 150                         next = curr->next;
 151
 152                         index = mhashFunction(curr->key);
 153 #ifdef DEBUG
 154                         printf("DEBUG(resize) -> index = %d, key = %d, val = %x\n", index, curr->key, curr->val);
 155 #endif
 156                         // Insert into the new table
 157                         if(mlookup.table[index].next == NULL && mlookup.table[index].key == 0) {
 158                                 mlookup.table[index].key = curr->key;
 159                                 mlookup.table[index].val = curr->val;
 160                                 mlookup.numelements++;
 161                         }else {
 162                                 if((newnode = calloc(1, sizeof(mhashlistnode_t))) == NULL) {
 163                                         printf("Calloc error %s, %d\n", __FILE__, __LINE__);
 164                                         return 1;
 165                                 }
 166                                 newnode->key = curr->key;
 167                                 newnode->val = curr->val;
 168                                 newnode->next = mlookup.table[index].next;
 169                                 mlookup.table[index].next = newnode;
 170                                 mlookup.numelements++;
 171                         }
 172
 173                         //free the linked list of mhashlistnode_t if not the first element in the hash table
 174                         if (isfirst != 1) {
 175                                 free(curr);
 176                         }
 177
 178                         isfirst = 0;
 179                         curr = next;
 180
 181                 }
 182         }
 183
 184         free(ptr);              //Free the memory of the old hash table
 185         return 0;
 186 }
 187
 188 unsigned int *mhashGetKeys(unsigned int *numKeys)
 189 {
 190         unsigned int *keys;
 191         int i, keyindex;
 192         mhashlistnode_t *curr;
 193
 194         pthread_mutex_lock(&mlookup.locktable);
 195
 196         *numKeys = mlookup.numelements;
 197         keys = calloc(*numKeys, sizeof(unsigned int));
 198
 199         keyindex = 0;
 200         for (i = 0; i < mlookup.size; i++)
 201         {
 202                 if (mlookup.table[i].key != 0)
 203                 {
 204                         curr = &mlookup.table[i];
 205                         while (curr != NULL)
 206                         {
 207                                 keys[keyindex++] = curr->key;
 208                                 curr = curr->next;
 209                         }
 210                 }
 211         }
 212
 213         if (keyindex != *numKeys)
 214                 printf("mhashGetKeys(): WARNING: incorrect mlookup.numelements value!\n");
 215
 216         pthread_mutex_unlock(&mlookup.locktable);
 217         return keys;
 218 }
 219