/**
* 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();
}
}
}
/**
* Deletes the heap file from the database, freeing all of its pages.
*
* @throws ChainException
*/
public void deleteFile() throws ChainException {
if (delete) throw new ChainException(null, "files have already been deleted");
for (int i = 0; i < pages.size(); i++)
try {
global.Minibase.DiskManager.deallocate_page(pages.get(i));
} catch (Exception e) {
throw new ChainException(null, "fail to deallocate page");
}
global.Minibase.DiskManager.delete_file_entry(name);
pages = null;
pids = null;
recordNumber = 0;
delete = true;
}