Пример #1
0
 /**
  * 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();
 }
Пример #2
0
  /**
   * 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();
      }
    }
  }
Пример #3
0
  /**
   * 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;
  }