/**
* Reads a record from the file, given its id.
*
* @throws IllegalArgumentException if the rid is invalid
*/
public byte[] selectRecord(RID rid) {
PageId pid = rid.pageno;
if (!pids.contains(pid.pid)) throw new IllegalArgumentException("the RID is invalid");
Page page = new Page();
global.Minibase.BufferManager.pinPage(pid, page, false);
global.Minibase.BufferManager.unpinPage(pid, false);
return page.getData();
}
/**
* If the given name already denotes a file, this opens it; otherwise, this creates a new empty
* file. A null name produces a temporary heap file which requires no DB entry.
*/
public HeapFile(String name) throws ChainException {
this.name = name;
PageId firstPageId;
Page page = new Page();
pages = new ArrayList<PageId>();
pids = new HashSet<Integer>();
if (name == null) {
// Temporary heap file
firstPageId = global.Minibase.BufferManager.newPage(page, 1);
current = new HFPage(page);
current.setCurPage(firstPageId);
pages.add(firstPageId);
pids.add(firstPageId.pid);
global.Minibase.BufferManager.unpinPage(firstPageId, true);
} else {
firstPageId = global.Minibase.DiskManager.get_file_entry(name);
if (firstPageId == null) {
firstPageId = global.Minibase.BufferManager.newPage(page, 1);
global.Minibase.DiskManager.add_file_entry(name, firstPageId);
global.Minibase.BufferManager.unpinPage(firstPageId, true);
pages.add(firstPageId);
pids.add(firstPageId.pid);
global.Minibase.BufferManager.pinPage(firstPageId, page, false);
recordNumber = 0;
current = new HFPage(page);
current.setCurPage(firstPageId);
global.Minibase.BufferManager.unpinPage(firstPageId, true);
return;
}
// add the new HFPages
global.Minibase.BufferManager.pinPage(firstPageId, page, false);
// System.err.println("hahahaha"+page.getData());
current = new HFPage(page);
current.setData(page.getData());
pages.add(firstPageId);
pids.add(firstPageId.pid);
recordNumber += amount(current);
global.Minibase.BufferManager.unpinPage(firstPageId, false);
PageId currentPageId = current.getNextPage();
while (currentPageId.pid != 0 & currentPageId.pid != -1) {
HFPage temp = new HFPage();
global.Minibase.BufferManager.pinPage(currentPageId, temp, false);
pages.add(currentPageId);
pids.add(currentPageId.pid);
recordNumber += amount(temp);
global.Minibase.BufferManager.unpinPage(currentPageId, false);
currentPageId = temp.getNextPage();
}
}
}
/**
* Inserts a new record into the file and returns its RID.
*
* @throws IllegalArgumentException if the record is too large
*/
public RID insertRecord(byte[] record) throws IllegalArgumentException, ChainException {
if (record.length > GlobalConst.MAX_TUPSIZE)
throw new IllegalArgumentException("the record's size is too large");
for (int i = 0; i < pages.size(); i++) {
PageId pid = pages.get(i);
Page page = new Page();
global.Minibase.BufferManager.pinPage(pid, page, false);
HFPage hfpage = new HFPage(page);
hfpage.setCurPage(pid);
hfpage.setData(page.getData());
if (hfpage.getFreeSpace() > record.length) {
RID rid = hfpage.insertRecord(record);
recordNumber++;
global.Minibase.BufferManager.unpinPage(pid, true);
return rid;
}
global.Minibase.BufferManager.unpinPage(pid, false);
}
Page page = new Page();
PageId pid = global.Minibase.BufferManager.newPage(page, 1);
HFPage hfpage = new HFPage(page);
// initialize HFPage
hfpage.initDefaults();
hfpage.setCurPage(pid);
// hfpage.print();
RID rid = hfpage.insertRecord(record);
pages.add(pid);
pids.add(pid.pid);
hfpage.setNextPage(pid);
hfpage.setPrevPage(current.getCurPage());
current = hfpage;
global.Minibase.BufferManager.unpinPage(pid, true);
// hfpage.print();
// System.out.println ("The PID is "+pid);
recordNumber++;
return rid;
}