+++ /dev/null
-/************************************************************************************************
- IMP NOTE:
- All llookup hash function prototypes returns 0 on sucess and 1 otherwise
- llookup hash is an array of lhashlistnode_t
- oid = mid = 0 in a given lhashlistnode_t for each bin in the hash table ONLY if the entry is empty =>
- the OID's can be any unsigned int except 0
-
- Uses pthreads. compile using -lpthread option
-***************************************************************************************************/
-#include "llookup.h"
-
-lhashtable_t llookup; //Global Hash table
-
-// Creates a hash table with size and an array of lhashlistnode_t
-unsigned int lhashCreate(unsigned int size, float loadfactor) {
- lhashlistnode_t *nodes;
- int i;
-
- // Allocate space for the hash table
- if((nodes = calloc(size, sizeof(lhashlistnode_t))) == NULL) {
- printf("Calloc error %s %d\n", __FILE__, __LINE__);
- return 1;
- }
-
- llookup.table = nodes;
- llookup.size = size;
- llookup.numelements = 0; // Initial number of elements in the hash
- llookup.loadfactor = loadfactor;
- //Initialize the pthread_mutex variable
- pthread_mutex_init(&llookup.locktable, NULL);
- return 0;
-}
-
-// Assign to oids to bins inside hash table
-unsigned int lhashFunction(unsigned int oid) {
- return( oid % (llookup.size));
-}
-
-// Insert oid and mid mapping into the hash table
-unsigned int lhashInsert(unsigned int oid, unsigned int mid) {
- unsigned int newsize;
- int index;
- lhashlistnode_t *ptr, *node;
-
- if (llookup.numelements > (llookup.loadfactor * llookup.size)) {
- //Resize Table
- newsize = 2 * llookup.size + 1;
- pthread_mutex_lock(&llookup.locktable);
- lhashResize(newsize);
- pthread_mutex_unlock(&llookup.locktable);
- }
-
- ptr = llookup.table;
- llookup.numelements++;
-
- index = lhashFunction(oid);
-#ifdef DEBUG
- printf("DEBUG(insert) oid = %d, mid =%d, index =%d\n",oid,mid, index);
-#endif
- pthread_mutex_lock(&llookup.locktable);
- if(ptr[index].next == NULL && ptr[index].oid == 0) { // Insert at the first position in the hashtable
- ptr[index].oid = oid;
- ptr[index].mid = mid;
- } else { // Insert in the linked list
- if ((node = calloc(1, sizeof(lhashlistnode_t))) == NULL) {
- printf("Calloc error %s, %d\n", __FILE__, __LINE__);
- pthread_mutex_unlock(&llookup.locktable);
- return 1;
- }
- node->oid = oid;
- node->mid = mid;
- node->next = ptr[index].next;
- ptr[index].next = node;
- }
-
- pthread_mutex_unlock(&llookup.locktable);
- return 0;
-}
-
-// Return mid for a given oid in the hash table
-unsigned int lhashSearch(unsigned int oid) {
- int index;
- lhashlistnode_t *ptr, *node;
-
- ptr = llookup.table; // Address of the beginning of hash table
- index = lhashFunction(oid);
- node = &ptr[index];
- pthread_mutex_lock(&llookup.locktable);
- while(node != NULL) {
- if(node->oid == oid) {
- pthread_mutex_unlock(&llookup.locktable);
- return node->mid;
- }
- node = node->next;
- }
- pthread_mutex_unlock(&llookup.locktable);
- return 0;
-}
-
-// Remove an entry from the hash table
-unsigned int lhashRemove(unsigned int oid) {
- int index;
- lhashlistnode_t *curr, *prev;
- lhashlistnode_t *ptr, *node;
-
- ptr = llookup.table;
- index = lhashFunction(oid);
- curr = &ptr[index];
-
- pthread_mutex_lock(&llookup.locktable);
- for (; curr != NULL; curr = curr->next) {
- if (curr->oid == oid) { // Find a match in the hash table
- llookup.numelements--; // Decrement the number of elements in the global hashtable
- if ((curr == &ptr[index]) && (curr->next == NULL)) { // Delete the first item inside the hashtable with no linked list of lhashlistnode_t
- curr->oid = 0;
- curr->mid = 0;
- } else if ((curr == &ptr[index]) && (curr->next != NULL)) { //Delete the first item with a linked list of lhashlistnode_t connected
- curr->oid = curr->next->oid;
- curr->mid = curr->next->mid;
- node = curr->next;
- curr->next = curr->next->next;
- free(node);
- } else { // Regular delete from linked listed
- prev->next = curr->next;
- free(curr);
- }
- pthread_mutex_unlock(&llookup.locktable);
- return 0;
- }
- prev = curr;
- }
- pthread_mutex_unlock(&llookup.locktable);
- return 1;
-}
-
-// Resize table
-unsigned int lhashResize(unsigned int newsize) {
- lhashlistnode_t *node, *ptr, *curr, *next; // curr and next keep track of the current and the next lhashlistnodes in a linked list
- unsigned int oldsize;
- int isfirst; // Keeps track of the first element in the lhashlistnode_t for each bin in hashtable
- int i,index;
- lhashlistnode_t *newnode;
-
- ptr = llookup.table;
- oldsize = llookup.size;
-
- if((node = calloc(newsize, sizeof(lhashlistnode_t))) == NULL) {
- printf("Calloc error %s %d\n", __FILE__, __LINE__);
- return 1;
- }
-
- llookup.table = node; //Update the global hashtable upon resize()
- llookup.size = newsize;
- llookup.numelements = 0;
-
- for(i = 0; i < oldsize; i++) { //Outer loop for each bin in hash table
- curr = &ptr[i];
- isfirst = 1;
- while (curr != NULL) { //Inner loop to go through linked lists
- if (curr->oid == 0) { //Exit inner loop if there the first element for a given bin/index is NULL
- break; //oid = mid =0 for element if not present within the hash table
- }
- next = curr->next;
- index = lhashFunction(curr->oid);
- // Insert into the new table
- if(llookup.table[index].next == NULL && llookup.table[index].oid == 0) {
- llookup.table[index].oid = curr->oid;
- llookup.table[index].mid = curr->mid;
- llookup.numelements++;
- }else {
- if((newnode = calloc(1, sizeof(lhashlistnode_t))) == NULL) {
- printf("Calloc error %s, %d\n", __FILE__, __LINE__);
- return 1;
- }
- newnode->oid = curr->oid;
- newnode->mid = curr->mid;
- newnode->next = llookup.table[index].next;
- llookup.table[index].next = newnode;
- llookup.numelements++;
- }
-
- //free the linked list of lhashlistnode_t if not the first element in the hash table
- if (isfirst != 1) {
- free(curr);
- }
-
- isfirst = 0;
- curr = next;
-
- }
- }
-
- free(ptr); //Free the memory of the old hash table
- return 0;
-}
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