void FileSystem::deleteFromFS(std::string remoteFile)
{
// hashing function to find the machine/s where to store the file;
int fileKey = hashString(remoteFile);
int position = findPositionByKey(fileKey);
// cout<<"delete " << fileKey << " from "<<position<<" "<<virtualRing[position].ip_str<<" "<<virtualRing[position].key<<endl;
bool attempt = deleteFromNode( position, remoteFile );
if( !attempt)
{
std::cout << "Problem removing at position " << position << std::endl;
}
attempt = deleteFromNode( position+1, remoteFile );
//if(attempt)
//return;
attempt = deleteFromNode( position+2, remoteFile );
//if(attempt)
//return;
//std::string destAddress = "localhost";
//put(destAddress, localFile, remoteFile);
}
void BPlusTree::deleteEntry(int key) {
BufferManager *bm = BufferManager::getInstance();
//lookup till the required node
TreeNode* c = root;
while( c->isLeaf() ) {
int sKey = -1;
int finalKey = -1;
for(int i=0; i<(c->getTotalPairs()); i++){
sKey=c->getKey(i);
if(sKey>key){
finalKey=i;
break;
}
}
if(finalKey==-1) {
int m=c->getTotalPairs();
c = new TreeNode(bm->pinPage(dbName, c->getRid(m)));
}
else
c = new TreeNode(bm->pinPage(dbName, c->getRid(finalKey)));
}
deleteFromNode(c, key);
}
void BPlusTree::deleteFromNode(TreeNode* N, int key) {
BufferManager *bm = BufferManager::getInstance();
//finding the location of pair to be deleted
int i;
for(i=1;i<=N->getTotalPairs();i++) {
if(N->getKey(i)==key) break;
}
//deleting the pair
moveBytes( N->getBuffPage(), 8*i, 8+8*i, (N->getTotalPairs()-i+1)*8+4 );
N->updateSlot(1, N->getTotalPairs()-1);
//if N is root AND has only one child
if(N->getSlot(BLOCK_SIZE/4)==-1 && N->getSlot(1)==1) {
//delete that node and make its only child as root
int newRootId = N->getSlot(3);
root = new TreeNode(bm->pinPage(dbName, N->getSlot(3)));
int blockToFree = N->getSlot(BLOCK_SIZE/4-1);
bm->unpinPage(dbName, blockToFree, true);
StorageManager::freeBlock(dbName, blockToFree);
root->updateSlot(BLOCK_SIZE/4, -1);
}
else {
int parentPtr = readInt(N->getBuffPage(), BLOCK_SIZE-4);
TreeNode* parent = new TreeNode(bm->pinPage(dbName, parentPtr));
int loc=parent->findPtr(N->getNodeId());
bool correct;
int NDashId,keyDash;
//finding next or previous node and the value between them
if(loc>1) {
correct=true;
NDashId = loc-1;
keyDash = parent->getKey(loc-1);
} else {
correct=false;
NDashId = loc+1;
keyDash = parent->getKey(loc);
}
TreeNode* NDash = new TreeNode(bm->pinPage(dbName, NDashId));
//if N and NDash can coalesce in one node
if(N->getTotalPairs()+NDash->getTotalPairs()-1 == BT_N) {
//swapping if successive nodes r in reverse order
if(correct==false) {
TreeNode* temp;
temp = N;
N = NDash;
NDash = temp;
}
//coalescing nodes
if(!N->isLeaf()) {
int num = NDash->getTotalPairs();
NDash->updateSlot(2*NDash->getTotalPairs()+2, keyDash);
for(int i=0;i<(N->getTotalPairs()*2);i++) {
NDash->updateSlot(2*NDash->getTotalPairs()+2+i, N->getSlot(i+2));
NDash->updateSlot(1,NDash->getTotalPairs()+num);
}
}
else {
int num = NDash->getTotalPairs();
NDash->updateSlot(2*NDash->getTotalPairs()+2, keyDash);
for(int i=0;i<(N->getTotalPairs()*2);i++)
NDash->updateSlot(2*NDash->getTotalPairs()+2+i, N->getSlot(i+2));
NDash->updateSlot(1,NDash->getTotalPairs()+num);
NDash->updateSlot(2+2*BT_N+1,N->getSlot(2+2*BT_N+1));
}
deleteFromNode(parent, keyDash);
}
//if NDash is predecessor
if(correct==true){
if(!N->isLeaf()) {
//removing last key and pointer to next leaf
int lastKey = NDash->getSlot(2+NDash->getTotalPairs()*2);
int lastPtr = NDash->getSlot(2+NDash->getTotalPairs()*2+1);
NDash->updateSlot(1,NDash->getTotalPairs()+1);
//adding one pair to N
moveBytes(N->getBuffPage(), 16, 8, N->getTotalPairs()*8+4);
N->updateSlot(1, N->getTotalPairs()+1);
N->updateSlot(3, lastPtr);
N->updateSlot(4, keyDash);
//replacing keyDash in parent by the removed key
int location = parent->findKey(keyDash);
parent->updateSlot(2+2*location, lastKey);
} else {
//removing last key and pointer to next leaf
int lastKey = NDash->getSlot(2+NDash->getTotalPairs()*2);
int lastPtr = NDash->getSlot(2+NDash->getTotalPairs()*2-1);
NDash->updateSlot(1,NDash->getTotalPairs()+1);
//adding one pair to N
moveBytes(N->getBuffPage(), 16, 8, N->getTotalPairs()*8);
N->updateSlot(1, N->getTotalPairs()+1);
N->updateSlot(3, lastPtr);
N->updateSlot(4, keyDash);
//replacing keyDash in parent by the removed key
int location = parent->findKey(keyDash);
parent->updateSlot(2+2*location, lastKey);
}
} else {
if(!NDash->isLeaf()) {
//removing last key and pointer to next leaf
int lastKey = N->getSlot(2+N->getTotalPairs()*2);
int lastPtr = N->getSlot(2+N->getTotalPairs()*2+1);
N->updateSlot(1,N->getTotalPairs()+1);
//adding one pair to NDash
moveBytes(NDash->getBuffPage(), 16, 8, NDash->getTotalPairs()*8+4);
NDash->updateSlot(1, NDash->getTotalPairs()+1);
NDash->updateSlot(3, lastPtr);
NDash->updateSlot(4, keyDash);
//replacing keyDash in parent by the removed key
int location = parent->findKey(keyDash);
parent->updateSlot(2+2*location, lastKey);
} else {
//removing last key and pointer to next leaf
int lastKey = N->getSlot(2+N->getTotalPairs()*2);
int lastPtr = N->getSlot(2+N->getTotalPairs()*2-1);
N->updateSlot(1,N->getTotalPairs()+1);
//adding one pair to NDash
moveBytes(NDash->getBuffPage(), 16, 8, NDash->getTotalPairs()*8);
NDash->updateSlot(1, NDash->getTotalPairs()+1);
NDash->updateSlot(3, lastPtr);
NDash->updateSlot(4, keyDash);
//replacing keyDash in parent by the removed key
int location = parent->findKey(keyDash);
parent->updateSlot(2+2*location, lastKey);
}
}
}
}
