/** Suck up tuples from the source file. */
private Tuple readNextTuple(DataInputStream dis, int slotId) throws NoSuchElementException {
// if associated bit is not set, read forward to the next tuple, and
// return null.
if (!getSlot(slotId)) {
for (int i = 0; i < td.getSize(); i++) {
try {
dis.readByte();
} catch (IOException e) {
throw new NoSuchElementException("error reading empty tuple");
}
}
return null;
}
// read fields in the tuple
Tuple t = new Tuple(td);
RecordID rid = new RecordID(pid, slotId);
t.setRecordID(rid);
try {
for (int j = 0; j < td.numFields(); j++) {
Field f = td.getType(j).parse(dis);
t.setField(j, f);
}
} catch (java.text.ParseException e) {
// e.printStackTrace();
throw new NoSuchElementException("parsing error!");
}
return t;
}
/**
* Generates a byte array representing the contents of this page. Used to serialize this page to
* disk.
*
* <p>The invariant here is that it should be possible to pass the byte array generated by
* getPageData to the HeapPage constructor and have it produce an identical HeapPage object.
*
* @see #HeapPage
* @return A byte array correspond to the bytes of this page.
*/
public byte[] getPageData() {
// int len = header.length*4 + BufferPool.PAGE_SIZE;
int len = BufferPool.PAGE_SIZE;
ByteArrayOutputStream baos = new ByteArrayOutputStream(len);
DataOutputStream dos = new DataOutputStream(baos);
// create the header of the page
try {
dos.write(header.getHeader());
} catch (IOException e) {
// this really shouldn't happen
e.printStackTrace();
}
// create the tuples
for (int i = 0; i < numSlots; i++) {
// empty slot
if (!getSlot(i)) {
for (int j = 0; j < td.getSize(); j++) {
try {
dos.writeByte(0);
} catch (IOException e) {
e.printStackTrace();
}
}
continue;
}
// non-empty slot
for (int j = 0; j < td.numFields(); j++) {
Field f = tuples[i].getField(j);
try {
f.serialize(dos);
} catch (IOException e) {
e.printStackTrace();
}
}
}
// padding
int zerolen = BufferPool.PAGE_SIZE - numSlots * td.getSize() - header.length();
byte[] zeroes = new byte[zerolen];
try {
dos.write(zeroes, 0, zerolen);
} catch (IOException e) {
e.printStackTrace();
}
try {
dos.flush();
} catch (IOException e) {
e.printStackTrace();
}
return baos.toByteArray();
}
public Tuple getNext() throws NoSuchElementException, TransactionAbortedException {
try {
Tuple tuple = new Tuple(td);
for (int i = 0; i < td.numFields(); i++) {
IntField intf = IntField.createIntField(in.readInt());
tuple.setField(i, intf);
}
return tuple;
} catch (EOFException eof) {
throw new NoSuchElementException(eof.getMessage());
} catch (Exception e) {
e.printStackTrace();
BufferPool.Instance().abortTransaction(tid);
closeConnection();
throw new TransactionAbortedException(e);
}
}