bool BANDB::remove(int transID, int key) {
int pageIndex = bm->findKey(key);
if (pageIndex == -1) { return false; }
int pageNum = bm->getNumAtIndex(pageIndex);
Record* oldRecP = bm->locateRecord(pageIndex, key);
Record oldRec = *oldRecP;
char* oldData = (char*) &oldRec;
char empty[16] = {};
for (int i = 0; i < 16; i++) { empty[i] = 0; }
bool result = bm->removeRecord(pageIndex, key);
lm->writeWriteRecord(transID, pageNum, oldData, empty);
return result;
}
void BANDB::rollbackWork(int transID, int savepoint) {
int undoNext = lm->txnTable.locateTxnRecord(transID)->lastLSN;
while (undoNext > savepoint) {
LogRecord lr = lm->log[undoNext-1];
if (lr.type == 2) {
// first, we recover the old record, which gives us the key and data
Record* r = new Record(lr.oldData);
// now we write over the data in the page:
int pageIndex = bm->findKey(r->key);
if (pageIndex == -1) { pageIndex = bm->findKey(0); }
int pageNum = bm->getNumAtIndex(pageIndex);
// If this was an insert, old data will be null, so we need to recover
// the key from "new data" and remove it from the db
if (r->key == 0) {
Record* r2 = new Record(lr.newData);
pageIndex = bm->findKey(r2->key);
pageNum = bm->getNumAtIndex(pageIndex);
bm->removeRecord(pageIndex, r2->key);
} else {
bm->insertRecord(pageIndex, r->key, r->data);
}
// then write the CLR
lm->writeRollbackRecord(transID, undoNext, r->data);
}
undoNext = lr.prevLSN;
}
// If we rolled it back all the way, we are in the abort state
TxnRecord* rec = lm->txnTable.locateTxnRecord(transID);
if (undoNext == 0) {
rec->state = 4;
} else {
rec->state = 1;
}
}
