public StructuralSummaryNode next() throws IOException, DBException // for Iterator
{
// read record from file
// transform into ssNode
int CID;
int qNameLen;
String qName;
byte[] qNameSeq;
int parentCID;
StructuralSummaryNode currentNode = new StructuralSummaryNode();
int nextPage; // needed in case that data is written in more than one page
while (true) {
// if(unTakenNodes!=0 &&XBufferChannel.position()+2*Settings.sizeOfInt<=Settings.pageSize)
// agar dorost bkhunim har bar position sare yek record mi iste:
if (unTakenNodes != 0 && xBufferChannel.position() < freeOffset) {
// bayd daghigh tar chek bshe.
// stroage format in ssIndex: cid(int),qlen(int),qSeq(byte array),parentCId(int)
CID = xBufferChannel.getInt();
logManager.LogManager.log(1, "CID: " + CID);
qNameLen = xBufferChannel.getInt();
int reqSpace = qNameLen + Settings.sizeOfInt;
int capacity = Settings.pageSize - xBufferChannel.position();
if (reqSpace <= capacity) {
qNameSeq = new byte[qNameLen];
xBufferChannel.get(qNameSeq, 0, qNameLen);
qName = new String(qNameSeq);
parentCID = xBufferChannel.getInt();
currentNode.setCID(CID);
currentNode.setParentCID(parentCID);
currentNode.setQName(qName);
unTakenNodes--;
return currentNode; // return breaks loop!
}
} else {
// if(unTakenNodes==0)//in k ghalate baz :(
// { return null; }
// else //if(XBufferChannel.position()+2*Settings.sizeOfInt>Settings.pageSize)
// { //goTOnextPAge;
xBufferChannel.position(Settings.nextPagePos);
nextPage = xBufferChannel.getInt();
bufMngr.unpinBuffer(xBufferChannel);
if (nextPage > 0) {
loadSSPage(nextPage); // prepares XBufferChannel and loads page into it.
// System.out.println("loaded:"+nextPage);
} else return null;
workingPage = nextPage;
xBufferChannel.position(
Settings.dataStartPos); // instead of calling open(somehow opens nextpage)
// }
}
} // end while
}
public void endDoc() throws IOException {
bufMngr.unpinBuffer(xBufferChannel, true);
}
public void add(int CID, String qName, int parentCID) throws IOException, DBException {
boolean keyFound = false;
byte[] qNameArray;
int qLength;
// we need this in case that keys being added exceed page size:
// storage format in ssIndex: cid(int),qlen(int),qSeq(byte array),parentCId(int)
qNameArray = qName.getBytes();
qLength = qNameArray.length; // qname only
xBufferChannel.position(freeOffset); // Every Iteration it must be set.
int capacity = Settings.pageSize - freeOffset;
int reqSpace = qLength + 3 * Settings.sizeOfInt;
if (reqSpace <= capacity) {
xBufferChannel.putInt(CID); // CID
// logManager.LogManager.log(0,"QNAME: "+ qName);
// logManager.LogManager.log(0,"Position: "+ xBufferChannel.position());
xBufferChannel.putInt(qLength);
xBufferChannel.put(qNameArray, 0, qLength);
xBufferChannel.putInt(parentCID); // parentCId
numOfKeys++;
freeOffset += (qLength + 3 * Settings.sizeOfInt);
} else {
// must add page
// twinNode=new BTreeNode(indexName,(byte)0,(byte)1, -1);//numOfKeys is not valid yet
XBufferChannel hlpr = bufMngr.getFreePage();
workingPage = hlpr.getPageNumber();
logManager.LogManager.log(5, "Structural Sum P: " + workingPage);
// numOfKeys=keysAdded;
// unTakenRecs=numOfKeys;maybe we need this in the future
xBufferChannel.position(Settings.nextPagePos);
xBufferChannel.putInt(workingPage);
// if(workingPage==19995)
// logManager.LogManager.log(5, "nextPage:19915"+"workingPage:
// "+xBufferChannel.getPageNumber());
xBufferChannel.position(Settings.freeOffsetPos); // not needed
xBufferChannel.putInt(freeOffset);
// if(freeOffset==511)
// logManager.LogManager.log(5,"freeOffset: "+ freeOffset);
xBufferChannel.position(Settings.numOfKeysPos);
xBufferChannel.putInt(numOfKeys);
// if(numOfKeys==26)
// logManager.LogManager.log(5,"numOfKeys: "+ numOfKeys);
bufMngr.unpinBuffer(xBufferChannel, true);
changeWorkingPageTo(hlpr);
// write remaining record:
xBufferChannel.putInt(CID); // CID
xBufferChannel.putInt(qLength);
xBufferChannel.put(qNameArray, 0, qLength);
xBufferChannel.putInt(parentCID); // parentCId
numOfKeys++;
freeOffset += (qLength + 3 * Settings.sizeOfInt);
}
// unTakenRecs=numOfKeys;maybe we need this in the future
// here nexP should be -1 cause there is no page after!
xBufferChannel.position(Settings.freeOffsetPos);
xBufferChannel.putInt(freeOffset);
xBufferChannel.position(Settings.numOfKeysPos);
xBufferChannel.putInt(numOfKeys);
/// bufMngr.unpinBuffer(xBufferChannel, true);
}