void AntiCacheEvictionManager::printLRUChain(PersistentTable* table, int max, bool forward)
{
VOLT_INFO("num tuples in chain: %d", table->getNumTuplesInEvictionChain());
VOLT_INFO("oldest tuple id: %u", table->getOldestTupleID());
VOLT_INFO("newest tuple id: %u", table->getNewestTupleID());
char chain[max * 4];
int tuple_id;
TableTuple tuple = table->tempTuple();
if(forward)
tuple_id = table->getOldestTupleID();
else
tuple_id = table->getNewestTupleID();
chain[0] = '\0';
int iterations = 0;
while(iterations < table->getNumTuplesInEvictionChain() && iterations < max)
{
strcat(chain, itoa(tuple_id));
strcat(chain, " ");
tuple.move(table->dataPtrForTuple(tuple_id));
if(forward)
tuple_id = tuple.getNextTupleInChain();
else
tuple_id = tuple.getPreviousTupleInChain();
iterations++;
}
VOLT_INFO("LRU CHAIN: %s", chain);
}
// for the double linked list we start from the tail of the chain and iterate backwards
bool AntiCacheEvictionManager::removeTupleDoubleLinkedList(PersistentTable* table, uint32_t removal_id) {
bool tuple_found = false;
int tuples_in_chain;
// ids for iterating through the list
uint32_t current_tuple_id;
uint32_t previous_tuple_id;
uint32_t next_tuple_id;
uint32_t oldest_tuple_id;
// assert we have tuples in the eviction chain before we try to remove anything
tuples_in_chain = table->getNumTuplesInEvictionChain();
if (tuples_in_chain <= 0)
return false;
previous_tuple_id = 0;
oldest_tuple_id = table->getOldestTupleID();
current_tuple_id = table->getNewestTupleID(); // start iteration at back of chain
// set the tuple to the back of the chain (i.e. the newest)
TableTuple tuple = table->tempTuple();
tuple.move(table->dataPtrForTuple(current_tuple_id));
// we're removing the tail of the chain, i.e. the newest tuple
if (table->getNewestTupleID() == removal_id) {
if (table->getNumTuplesInEvictionChain() == 1) { // this is the only tuple in the chain
table->setOldestTupleID(0);
table->setNewestTupleID(0);
} else if(table->getNumTuplesInEvictionChain() == 2) {
table->setNewestTupleID(oldest_tuple_id);
table->setOldestTupleID(oldest_tuple_id);
}
else {
tuple.move(table->dataPtrForTuple(table->getNewestTupleID()));
// we need the previous tuple in the chain, since we're iterating from back to front
previous_tuple_id = tuple.getPreviousTupleInChain();
table->setNewestTupleID(previous_tuple_id);
}
tuple_found = true;
}
// we're removing the head of the chain, i.e. the oldest tuple
if(table->getOldestTupleID() == removal_id && !tuple_found) {
if (table->getNumTuplesInEvictionChain() == 1) { // this is the only tuple in the chain
table->setOldestTupleID(0);
table->setNewestTupleID(0);
}
else if(table->getNumTuplesInEvictionChain() == 2) {
table->setNewestTupleID(table->getNewestTupleID());
table->setOldestTupleID(table->getNewestTupleID());
}
else {
tuple.move(table->dataPtrForTuple(table->getOldestTupleID()));
next_tuple_id = tuple.getNextTupleInChain();
table->setOldestTupleID(next_tuple_id);
}
tuple_found = true;
}
int iterations = 0;
while(!tuple_found && iterations < table->getNumTuplesInEvictionChain()) {
if(current_tuple_id == oldest_tuple_id)
break;
// we've found the tuple we want to remove
if (current_tuple_id == removal_id) {
next_tuple_id = tuple.getPreviousTupleInChain();
// point previous tuple in chain to next tuple
tuple.move(table->dataPtrForTuple(previous_tuple_id));
tuple.setPreviousTupleInChain(next_tuple_id);
// point next tuple in chain to previous tuple
tuple.move(table->dataPtrForTuple(next_tuple_id));
tuple.setNextTupleInChain(previous_tuple_id);
tuple_found = true;
break;
}
// advance pointers
previous_tuple_id = current_tuple_id;
current_tuple_id = tuple.getPreviousTupleInChain(); // iterate back to front
tuple.move(table->dataPtrForTuple(current_tuple_id));
iterations++;
}
if (tuple_found) {
tuples_in_chain = table->getNumTuplesInEvictionChain();
--tuples_in_chain;
table->setNumTuplesInEvictionChain(tuples_in_chain);
return true;
}
return false;
}