3 mhashtable_t mlookup; //Global hash table
5 // Creates a machine lookup table with size =" size"
6 unsigned int mhashCreate(unsigned int size, float loadfactor) {
7 mhashlistnode_t *nodes;
10 // Allocate space for the hash table
11 if((nodes = calloc(size, sizeof(mhashlistnode_t))) == NULL) {
12 printf("Calloc error %s %d\n", __FILE__, __LINE__);
16 mlookup.table = nodes;
18 mlookup.numelements = 0; // Initial number of elements in the hash
19 mlookup.loadfactor = loadfactor;
20 //Initialize the pthread_mutex variable
21 pthread_mutex_init(&mlookup.locktable, NULL);
25 // Assign to keys to bins inside hash table
26 unsigned int mhashFunction(unsigned int key) {
27 return( key % (mlookup.size));
30 // Insert value and key mapping into the hash table
31 unsigned int mhashInsert(unsigned int key, void *val) {
34 mhashlistnode_t *ptr, *node;
36 if (mlookup.numelements > (mlookup.loadfactor * mlookup.size)) {
38 newsize = 2 * mlookup.size + 1;
39 pthread_mutex_lock(&mlookup.locktable);
41 pthread_mutex_unlock(&mlookup.locktable);
44 mlookup.numelements++;
46 index = mhashFunction(key);
48 printf("DEBUG -> index = %d, key = %d, val = %x\n", index, key, val);
50 pthread_mutex_lock(&mlookup.locktable);
51 if(ptr[index].next == NULL && ptr[index].key == 0) { // Insert at the first position in the hashtable
54 } else { // Insert in the beginning of linked list
55 if ((node = calloc(1, sizeof(mhashlistnode_t))) == NULL) {
56 printf("Calloc error %s, %d\n", __FILE__, __LINE__);
61 node->next = ptr[index].next;
62 ptr[index].next = node;
64 pthread_mutex_unlock(&mlookup.locktable);
68 // Return val for a given key in the hash table
69 void *mhashSearch(unsigned int key) {
71 mhashlistnode_t *ptr, *node;
73 ptr = mlookup.table; // Address of the beginning of hash table
74 index = mhashFunction(key);
76 pthread_mutex_lock(&mlookup.locktable);
78 if(node->key == key) {
83 pthread_mutex_unlock(&mlookup.locktable);
87 // Remove an entry from the hash table
88 unsigned int mhashRemove(unsigned int key) {
90 mhashlistnode_t *curr, *prev;
91 mhashlistnode_t *ptr, *node;
94 index = mhashFunction(key);
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
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;
108 curr->next = curr->next->next;
110 } else { // Regular delete from linked listed
111 prev->next = curr->next;
118 pthread_mutex_unlock(&mlookup.locktable);
123 unsigned int mhashResize(unsigned int newsize) {
124 mhashlistnode_t *node, *ptr, *curr, *next; // curr and next keep track of the current and the next mhashlistnodes in a linked list
125 unsigned int oldsize;
126 int isfirst; // Keeps track of the first element in the mhashlistnode_t for each bin in hashtable
128 mhashlistnode_t *newnode;
131 oldsize = mlookup.size;
133 if((node = calloc(newsize, sizeof(mhashlistnode_t))) == NULL) {
134 printf("Calloc error %s %d\n", __FILE__, __LINE__);
138 mlookup.table = node; //Update the global hashtable upon resize()
139 mlookup.size = newsize;
140 mlookup.numelements = 0;
142 for(i = 0; i < oldsize; i++) { //Outer loop for each bin in hash table
145 while (curr != NULL) { //Inner loop to go through linked lists
146 if (curr->key == 0) { //Exit inner loop if there the first element for a given bin/index is NULL
147 break; //key = val =0 for element if not present within the hash table
151 index = mhashFunction(curr->key);
153 printf("DEBUG(resize) -> index = %d, key = %d, val = %x\n", index, curr->key, curr->val);
155 // Insert into the new table
156 if(mlookup.table[index].next == NULL && mlookup.table[index].key == 0) {
157 mlookup.table[index].key = curr->key;
158 mlookup.table[index].val = curr->val;
159 mlookup.numelements++;
161 if((newnode = calloc(1, sizeof(mhashlistnode_t))) == NULL) {
162 printf("Calloc error %s, %d\n", __FILE__, __LINE__);
165 newnode->key = curr->key;
166 newnode->val = curr->val;
167 newnode->next = mlookup.table[index].next;
168 mlookup.table[index].next = newnode;
169 mlookup.numelements++;
172 //free the linked list of mhashlistnode_t if not the first element in the hash table
183 free(ptr); //Free the memory of the old hash table
189 vkey resize(obj_addr_table_t * table){
190 int newCapacity = 2*(table->size) + 1;
191 obj_listnode_t **old;
192 //if ((table->hash = (obj_listnode_t **) malloc(sizeof(obj_listnode_t *)*size)) == NULL) {
195 // Hashing for the Key
196 int hashKey(unsigned int key, obj_addr_table_t *table) {
198 int c2=0x27d4eb2d; // a prime or an odd constant
199 key = (key ^ 61) ^ (key >> 16);
200 key = key + (key << 3);
201 key = key ^ (key >> 4);
203 key = key ^ (key >> 15);
204 printf("The bucket number is %d\n", key % (table->size));
205 return (key % (table->size));
208 //Add key and its address to the new ob_listnode_t
209 vkey addKey(unsigned int key, objheader_t *ptr, obj_addr_table_t *table) {
211 obj_listnode_t *node;
213 table->numelements++;
214 if(table->numelements > (table->loadfactor * table->size)){
215 //TODO : check if table is nearly full and then resize
218 index = hashKey(key,table);
219 if ((node = (obj_listnode_t *) malloc(sizeof(obj_listnode_t))) == NULL) {
220 printf("Malloc error %s %d\n", __FILE__, __LINE__);
225 node->next = table->hash[index];
226 table->hash[index] = node;
229 // Get the address of the object header for a given key
230 objheader_t *findKey(unsigned int key, obj_addr_table_t *table) {
234 index = hashKey(key,table);
235 ptr = table->hash[index];
237 if (ptr->key == key) {
244 // Remove the pointer to the object header from a linked list of obj_listnode_t given an key
245 int removeKey(unsigned int key, obj_addr_table_t *table) {
247 obj_listnode_t *curr, *prev; // prev points to previous node and curr points to the node to be deleted
249 index = hashKey(key,table);
250 prev = curr = table->hash[index];
251 for (; curr != NULL; curr = curr->next) {
252 if (curr->key == key) { // Find a match in the hash table
253 table->numelements--;
254 prev->next = curr->next;
255 if (table->hash[index] == curr) { // Special case when there is one element pointed by the hash table
256 table->hash[index] = NULL;