Exemplo n.º 1
0
  /** 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;
  }
Exemplo n.º 2
0
  /**
   * 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();
  }
Exemplo n.º 3
0
 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);
   }
 }