Robust/src/Runtime/DSTM/interface/llookup.c

   1 /************************************************************************************************
   2   IMP NOTE:
   3    All llookup hash function prototypes returns 0 on sucess and 1 otherwise
   4    llookup hash is an array of lhashlistnode_t
   5    oid = mid = 0 in a given lhashlistnode_t for each bin in the hash table ONLY if the entry is empty =>
   6    the OID's can be any unsigned int except 0
   7
   8    Uses pthreads. compile using -lpthread option
   9 ***************************************************************************************************/
  10 #include "llookup.h"
  11
  12 lhashtable_t llookup;           //Global Hash table
  13
  14 // Creates a hash table with size and an array of lhashlistnode_t
  15 unsigned int lhashCreate(unsigned int size, float loadfactor) {
  16         lhashlistnode_t *nodes;
  17         int i;
  18
  19         // Allocate space for the hash table
  20         if((nodes = calloc(size, sizeof(lhashlistnode_t))) == NULL) {
  21                 printf("Calloc error %s %d\n", __FILE__, __LINE__);
  22                 return 1;
  23         }
  24
  25         llookup.table = nodes;
  26         llookup.size = size;
  27         llookup.numelements = 0; // Initial number of elements in the hash
  28         llookup.loadfactor = loadfactor;
  29         //Initialize the pthread_mutex variable
  30         pthread_mutex_init(&llookup.locktable, NULL);
  31         return 0;
  32 }
  33
  34 // Assign to oids to bins inside hash table
  35 unsigned int lhashFunction(unsigned int oid) {
  36         return( oid % (llookup.size));
  37 }
  38
  39 // Insert oid and mid mapping into the hash table
  40 unsigned int lhashInsert(unsigned int oid, unsigned int mid) {
  41         unsigned int newsize;
  42         int index;
  43         lhashlistnode_t *ptr, *node;
  44
  45         if (llookup.numelements > (llookup.loadfactor * llookup.size)) {
  46                 //Resize Table
  47                 newsize = 2 * llookup.size + 1;
  48                 pthread_mutex_lock(&llookup.locktable);
  49                 lhashResize(newsize);
  50                 pthread_mutex_unlock(&llookup.locktable);
  51         }
  52
  53         ptr = llookup.table;
  54         llookup.numelements++;
  55
  56         index = lhashFunction(oid);
  57 #ifdef DEBUG
  58         printf("DEBUG(insert) oid = %d, mid =%d, index =%d\n",oid,mid, index);
  59 #endif
  60         pthread_mutex_lock(&llookup.locktable);
  61         if(ptr[index].next == NULL && ptr[index].oid == 0) {    // Insert at the first position in the hashtable
  62                 ptr[index].oid = oid;
  63                 ptr[index].mid = mid;
  64         } else {                        // Insert in the linked list
  65                 if ((node = calloc(1, sizeof(lhashlistnode_t))) == NULL) {
  66                         printf("Calloc error %s, %d\n", __FILE__, __LINE__);
  67                         pthread_mutex_unlock(&llookup.locktable);
  68                         return 1;
  69                 }
  70                 node->oid = oid;
  71                 node->mid = mid;
  72                 node->next = ptr[index].next;
  73                 ptr[index].next = node;
  74         }
  75
  76         pthread_mutex_unlock(&llookup.locktable);
  77         return 0;
  78 }
  79
  80 // Return mid for a given oid in the hash table
  81 unsigned int lhashSearch(unsigned int oid) {
  82         int index;
  83         lhashlistnode_t *ptr, *node;
  84
  85         ptr = llookup.table;    // Address of the beginning of hash table
  86         index = lhashFunction(oid);
  87         node = &ptr[index];
  88         pthread_mutex_lock(&llookup.locktable);
  89         while(node != NULL) {
  90                 if(node->oid == oid) {
  91                         pthread_mutex_unlock(&llookup.locktable);
  92                         return node->mid;
  93                 }
  94                 node = node->next;
  95         }
  96         pthread_mutex_unlock(&llookup.locktable);
  97         return 0;
  98 }
  99
 100 // Remove an entry from the hash table
 101 unsigned int lhashRemove(unsigned int oid) {
 102         int index;
 103         lhashlistnode_t *curr, *prev;
 104         lhashlistnode_t *ptr, *node;
 105
 106         ptr = llookup.table;
 107         index = lhashFunction(oid);
 108         curr = &ptr[index];
 109
 110         pthread_mutex_lock(&llookup.locktable);
 111         for (; curr != NULL; curr = curr->next) {
 112                 if (curr->oid == oid) {         // Find a match in the hash table
 113                         llookup.numelements--;  // Decrement the number of elements in the global hashtable
 114                         if ((curr == &ptr[index]) && (curr->next == NULL))  { // Delete the first item inside the hashtable with no linked list of lhashlistnode_t
 115                                 curr->oid = 0;
 116                                 curr->mid = 0;
 117                         } else if ((curr == &ptr[index]) && (curr->next != NULL)) { //Delete the first item with a linked list of lhashlistnode_t  connected
 118                                 curr->oid = curr->next->oid;
 119                                 curr->mid = curr->next->mid;
 120                                 node = curr->next;
 121                                 curr->next = curr->next->next;
 122                                 free(node);
 123                         } else {                                                // Regular delete from linked listed
 124                                 prev->next = curr->next;
 125                                 free(curr);
 126                         }
 127                         pthread_mutex_unlock(&llookup.locktable);
 128                         return 0;
 129                 }
 130                 prev = curr;
 131         }
 132         pthread_mutex_unlock(&llookup.locktable);
 133         return 1;
 134 }
 135
 136 // Resize table
 137 unsigned int lhashResize(unsigned int newsize) {
 138         lhashlistnode_t *node, *ptr, *curr, *next;      // curr and next keep track of the current and the next lhashlistnodes in a linked list
 139         unsigned int oldsize;
 140         int isfirst;    // Keeps track of the first element in the lhashlistnode_t for each bin in hashtable
 141         int i,index;
 142         lhashlistnode_t *newnode;
 143
 144         ptr = llookup.table;
 145         oldsize = llookup.size;
 146
 147         if((node = calloc(newsize, sizeof(lhashlistnode_t))) == NULL) {
 148                 printf("Calloc error %s %d\n", __FILE__, __LINE__);
 149                 return 1;
 150         }
 151
 152         llookup.table = node;           //Update the global hashtable upon resize()
 153         llookup.size = newsize;
 154         llookup.numelements = 0;
 155
 156         for(i = 0; i < oldsize; i++) {                  //Outer loop for each bin in hash table
 157                 curr = &ptr[i];
 158                 isfirst = 1;
 159                 while (curr != NULL) {                  //Inner loop to go through linked lists
 160                         if (curr->oid == 0) {           //Exit inner loop if there the first element for a given bin/index is NULL
 161                                 break;                  //oid = mid =0 for element if not present within the hash table
 162                         }
 163                         next = curr->next;
 164                         index = lhashFunction(curr->oid);
 165                         // Insert into the new table
 166                         if(llookup.table[index].next == NULL && llookup.table[index].oid == 0) {
 167                                 llookup.table[index].oid = curr->oid;
 168                                 llookup.table[index].mid = curr->mid;
 169                                 llookup.numelements++;
 170                         }else {
 171                                 if((newnode = calloc(1, sizeof(lhashlistnode_t))) == NULL) {
 172                                         printf("Calloc error %s, %d\n", __FILE__, __LINE__);
 173                                         return 1;
 174                                 }
 175                                 newnode->oid = curr->oid;
 176                                 newnode->mid = curr->mid;
 177                                 newnode->next = llookup.table[index].next;
 178                                 llookup.table[index].next = newnode;
 179                                 llookup.numelements++;
 180                         }
 181
 182                         //free the linked list of lhashlistnode_t if not the first element in the hash table
 183                         if (isfirst != 1) {
 184                                 free(curr);
 185                         }
 186
 187                         isfirst = 0;
 188                         curr = next;
 189
 190                 }
 191         }
 192
 193         free(ptr);              //Free the memory of the old hash table
 194         return 0;
 195 }