// see DbFile.java for javadocs
public ArrayList<Page> insertTuple(TransactionId tid, Tuple t)
throws DbException, IOException, TransactionAbortedException {
// some code goes here
BufferPool bp = Database.getBufferPool();
int id = getId(), i, slots;
ArrayList<Page> retlist = new ArrayList<Page>();
PageId pid = null;
HeapPage p = null;
for (i = 0; i < numPages(); i++) {
pid = new HeapPageId(id, i);
p = (HeapPage) bp.getPage(tid, pid, Permissions.READ_WRITE);
slots = p.getNumEmptySlots();
if (slots > 0) {
p.insertTuple(t);
retlist.add(p);
return retlist;
}
}
// create new page and add tuple to it
pid = new HeapPageId(id, i);
raf.setLength(raf.length() + BufferPool.PAGE_SIZE);
p = (HeapPage) bp.getPage(tid, pid, Permissions.READ_WRITE);
p.insertTuple(t);
retlist.add(p);
return retlist;
}
/** Unit test for HeapFile.readPage() */
@Test
public void readPage() throws Exception {
HeapPageId pid = new HeapPageId(hf.getId(), 0);
HeapPage page = (HeapPage) hf.readPage(pid);
// NOTE(ghuo): we try not to dig too deeply into the Page API here; we
// rely on HeapPageTest for that. perform some basic checks.
assertEquals(484, page.getNumEmptySlots());
assertTrue(page.isSlotUsed(1));
assertFalse(page.isSlotUsed(20));
}
// see DbFile.java for javadocs
public Page deleteTuple(TransactionId tid, Tuple t)
throws DbException, TransactionAbortedException {
// some code goes here
BufferPool bp = Database.getBufferPool();
RecordId rid = t.getRecordId();
if (rid == null) {
throw new DbException("Tuple is not a member of this file");
}
HeapPage p = (HeapPage) bp.getPage(tid, rid.getPageId(), Permissions.READ_WRITE);
p.deleteTuple(t);
return p;
}
// see DbFile.java for javadocs
public Page readPage(PageId pid) {
// some code goes here
if (pid.pageNumber() >= numPages()) {
throw new IllegalArgumentException("page not in file");
}
Page returnme = null;
byte[] data = HeapPage.createEmptyPageData();
long offset = (long) BufferPool.PAGE_SIZE * pid.pageNumber();
try {
raf.seek(offset);
for (int i = 0; i < data.length; i++) {
data[i] = raf.readByte();
}
returnme = new HeapPage((HeapPageId) pid, data);
} catch (EOFException eofe) {
eofe.printStackTrace();
} catch (IOException ioe) {
ioe.printStackTrace();
}
return returnme;
}
// Assumes pages cannot be modified while iterating over them
// Iterates over only valid tuples
public HeapPageIterator(HeapPage page) {
_page = page;
_currentTuple = 0;
_numTuples = _page.getNumValidTuples();
}