/* Get the index of a neighbor from its link-layer address */
static int
index_from_lladdr(const linkaddr_t *lladdr)
{
nbr_table_key_t *key;
/* Allow lladdr-free insertion, useful e.g. for IPv6 ND.
* Only one such entry is possible at a time, indexed by linkaddr_null. */
if(lladdr == NULL) {
lladdr = &linkaddr_null;
}
key = list_head(nbr_table_keys);
while(key != NULL) {
if(lladdr && linkaddr_cmp(lladdr, &key->lladdr)) {
return index_from_key(key);
}
key = list_item_next(key);
}
return -1;
}
/*---------------------------------------------------------------------------*/
static void
remove_key(nbr_table_key_t *least_used_key)
{
int i;
for(i = 0; i < MAX_NUM_TABLES; i++) {
if(all_tables[i] != NULL && all_tables[i]->callback != NULL) {
/* Call table callback for each table that uses this item */
nbr_table_item_t *removed_item = item_from_key(all_tables[i], least_used_key);
if(nbr_get_bit(used_map, all_tables[i], removed_item) == 1) {
all_tables[i]->callback(removed_item);
}
}
}
/* Empty used map */
used_map[index_from_key(least_used_key)] = 0;
/* Remove neighbor from list */
list_remove(nbr_table_keys, least_used_key);
}
/* Get an item from its key */
static nbr_table_item_t *
item_from_key(nbr_table_t *table, nbr_table_key_t *key)
{
return item_from_index(table, index_from_key(key));
}
/*---------------------------------------------------------------------------*/
static nbr_table_key_t *
nbr_table_allocate(void)
{
nbr_table_key_t *key;
int least_used_count = 0;
nbr_table_key_t *least_used_key = NULL;
key = memb_alloc(&neighbor_addr_mem);
if(key != NULL) {
return key;
} else {
/* No more space, try to free a neighbor.
* The replacement policy is the following: remove neighbor that is:
* (1) not locked
* (2) used by fewest tables
* (3) oldest (the list is ordered by insertion time)
* */
/* Get item from first key */
key = list_head(nbr_table_keys);
while(key != NULL) {
int item_index = index_from_key(key);
int locked = locked_map[item_index];
/* Never delete a locked item */
if(!locked) {
int used = used_map[item_index];
int used_count = 0;
/* Count how many tables are using this item */
while(used != 0) {
if((used & 1) == 1) {
used_count++;
}
used >>= 1;
}
/* Find least used item */
if(least_used_key == NULL || used_count < least_used_count) {
least_used_key = key;
least_used_count = used_count;
if(used_count == 0) { /* We won't find any least used item */
break;
}
}
}
key = list_item_next(key);
}
if(least_used_key == NULL) {
/* We haven't found any unlocked item, allocation fails */
return NULL;
} else {
/* Reuse least used item */
int i;
for(i = 0; i<MAX_NUM_TABLES; i++) {
if(all_tables[i] != NULL && all_tables[i]->callback != NULL) {
/* Call table callback for each table that uses this item */
nbr_table_item_t *removed_item = item_from_key(all_tables[i], least_used_key);
if(nbr_get_bit(used_map, all_tables[i], removed_item) == 1) {
all_tables[i]->callback(removed_item);
}
}
}
/* Empty used map */
used_map[index_from_key(least_used_key)] = 0;
/* Remove neighbor from list */
list_remove(nbr_table_keys, least_used_key);
/* Return associated key */
return least_used_key;
}
}
/*---------------------------------------------------------------------------*/
static nbr_table_key_t *
nbr_table_allocate(nbr_table_reason_t reason, void *data)
{
nbr_table_key_t *key;
int least_used_count = 0;
nbr_table_key_t *least_used_key = NULL;
key = memb_alloc(&neighbor_addr_mem);
if(key != NULL) {
return key;
} else {
#ifdef NBR_TABLE_FIND_REMOVABLE
const linkaddr_t *lladdr;
lladdr = NBR_TABLE_FIND_REMOVABLE(reason, data);
if(lladdr == NULL) {
/* Nothing found that can be deleted - return NULL to indicate failure */
PRINTF("*** Not removing entry to allocate new\n");
return NULL;
} else {
/* used least_used_key to indicate what is the least useful entry */
int index;
int locked = 0;
if((index = index_from_lladdr(lladdr)) != -1) {
least_used_key = key_from_index(index);
locked = locked_map[index];
}
/* Allow delete of locked item? */
if(least_used_key != NULL && locked) {
PRINTF("Deleting locked item!\n");
locked_map[index] = 0;
}
}
#endif /* NBR_TABLE_FIND_REMOVABLE */
if(least_used_key == NULL) {
/* No more space, try to free a neighbor.
* The replacement policy is the following: remove neighbor that is:
* (1) not locked
* (2) used by fewest tables
* (3) oldest (the list is ordered by insertion time)
* */
/* Get item from first key */
key = list_head(nbr_table_keys);
while(key != NULL) {
int item_index = index_from_key(key);
int locked = locked_map[item_index];
/* Never delete a locked item */
if(!locked) {
int used = used_map[item_index];
int used_count = 0;
/* Count how many tables are using this item */
while(used != 0) {
if((used & 1) == 1) {
used_count++;
}
used >>= 1;
}
/* Find least used item */
if(least_used_key == NULL || used_count < least_used_count) {
least_used_key = key;
least_used_count = used_count;
if(used_count == 0) { /* We won't find any least used item */
break;
}
}
}
key = list_item_next(key);
}
}
