depot.java

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  }
  /**
   * Get the size of the value of a record.
   * @param key a byte array of a key.
   * @return the size of the value of the corresponding record.
   * @throws DepotException if an error occures or no record corresponds.
   * @note Because this method does not read the entity of a record, it is faster than `get'.
   */
  public int vsiz(byte[] key) throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      int rv = dpvsiz(index, key, key.length);
      if(rv == -1) throw new DepotException(dpecode());
      return rv;
    }
  }
  /**
   * Initialize the iterator of the database handle.
   * @throws DepotException if an error occures.
   * @note The iterator is used in order to access the key of every record stored in a database.
   */
  public void iterinit() throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      if(dpiterinit(index) == 0) throw new DepotException(dpecode());
    }
  }
  /**
   * Get the next key of the iterator.
   * @return a byte array of the key of the next record.
   * @throws DepotException if an error occures or no record corresponds.
   * @note It is possible to access every record by iteration of calling this method.
   * However, it is not assured if updating the database is occurred while the iteration.
   * Besides, the order of this traversal access method is arbitrary, so it is not assured
   * that the order of storing matches the one of the traversal access.
   */
  public byte[] iternext() throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      byte[] val = dpiternext(index);
      if(val == null) throw new DepotException(dpecode());
      return val;
    }
  }
  /**
   * Set alignment of the database handle.
   * @param align the basic size of alignment.
   * @throws DepotException if an error occures.
   * @note If alignment is set to a database, the efficiency of overwriting values are improved.
   * The size of alignment is suggested to be average size of the values of the records to be
   * stored.  If alignment is positive, padding whose size is multiple number of the alignment
   * is placed.  If alignment is negative, as `vsiz' is the size of a value, the size of padding
   * is calculated with `(vsiz / pow(2, abs(align) - 1))'.  Because alignment setting is not
   * saved in a database, you should specify alignment every opening a database.
   */
  public void setalign(int align) throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      if(dpsetalign(index, align) == 0) throw new DepotException(dpecode());
    }
  }
  /**
   * Synchronize updating contents with the file and the device.
   * @throws DepotException if an error occures.
   * @note This method is useful when another process uses the connected database file.
   */
  public void sync() throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      if(dpsync(index) == 0) throw new DepotException(dpecode());
    }
  }
  /**
   * Optimize the database.
   * @param bnum the number of the elements of the bucket array.  If it is not more than 0, the
   * default value is specified.
   * @throws DepotException if an error occures.
   * @note In an alternating succession of deleting and storing with overwrite or concatenate,
   * dispensable regions accumulate.  This method is useful to do away with them.
   */
  public void optimize(int bnum) throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      if(dpoptimize(index, bnum) == 0) throw new DepotException(dpecode());
    }
  }
  /**
   * Get the name of the database.
   * @return the string of the name of the database.
   * @throws DepotException if an error occures.
   */
  public String name() throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      String buf = dpname(index);
      if(buf == null) throw new DepotException(dpecode());
      return buf;
    }
  }
  /**
   * Get the size of the database file.
   * @return the size of the database file.
   * @throws DepotException if an error occures.
   */
  public int fsiz() throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      int rv = dpfsiz(index);
      if(rv == -1) throw new DepotException(dpecode());
      return rv;
    }
  }
  /**
   * Get the number of the elements of the bucket array.
   * @return the number of the elements of the bucket array.
   * @throws DepotException if an error occures.
   */
  public int bnum() throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      int rv = dpbnum(index);
      if(rv == -1) throw new DepotException(dpecode());
      return rv;
    }
  }
  /**
   * Get the number of the used elements of the bucket array.
   * @return the number of the used elements of the bucket array.
   * @throws DepotException if an error occures.
   * @note This method is inefficient because it accesses all elements of the bucket array.
   */
  public int busenum() throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      int rv = dpbusenum(index);
      if(rv == -1) throw new DepotException(dpecode());
      return rv;
    }
  }
  /**
   * Get the number of the records stored in the database.
   * @return the number of the records stored in the database.
   * @throws DepotException if an error occures.
   */
  public int rnum() throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      int rv = dprnum(index);
      if(rv == -1) throw new DepotException(dpecode());
      return rv;
    }
  }
  /**
   * Check whether the database handle is a writer or not.
   * @return true if the handle is a writer, false if not.
   * @throws DepotException if an error occures.
   */
  public boolean writable() throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      return dpwritable(index) == 0 ? false : true;
    }
  }
  /**
   * Check whether the database has a fatal error or not.
   * @return true if the database has a fatal error, false if not.
   * @throws DepotException if an error occures.
   */
  public boolean fatalerror() throws DepotException {
    if(index < 0) throw new DepotException();
    synchronized(ADBM.class){
      return dpfatalerror(index) == 0 ? false : true;
    }
  }
  /**
   * Store a record.
   * @param key a byte array of a key.
   * @param val a byte array of a value.
   * @param replace whether the existing value is to be overwritten or not.
   * @throws DepotException if an error occures or replace is cancelled.
   */
  public void store(byte[] key, byte[] val, boolean replace) throws DepotException {
    put(key, val, replace ? DOVER : DKEEP);
  }
  /**
   * Delete a record.
   * @param key a byte array of a key.
   * @throws DepotException if an error occures or no record corresponds.
   */
  public void delete(byte[] key) throws DepotException {
    out(key);
  }
  /**
   * Fetch a record.
   * @param key a byte array of a key.
   * @return a byte array of the value of the corresponding record.
   * @throws DepotException if an error occures or no record corresponds.
   */
  public byte[] fetch(byte[] key) throws DepotException {
    return get(key, 0, -1);
  }
  /**
   * Get the first key.
   * @return a byte array of the key of the first record.
   * @throws DepotException if an error occures or no record corresponds.
   */
  public byte[] firstkey() throws DepotException {
    iterinit();
    return iternext();
  }
  /**
   * Get the next key.
   * @return a byte array of the key of the next record.
   * @throws DepotException if an error occures or no record corresponds.
   */
  public byte[] nextkey() throws DepotException {
    return iternext();
  }
  /**
   * Check whether a fatal error occured or not.
   * @return true if the database has a fatal error, false if not.
   * @throws DepotException if an error occures.
   */
  public boolean error() throws DepotException {
    return fatalerror();
  }
  //----------------------------------------------------------------
  // native methods
  //----------------------------------------------------------------
  private static synchronized final native void dpinit();
  private static synchronized final native String dpversion();
  private static synchronized final native int dpecode();
  private static synchronized final native String dperrmsg(int ecode);
  private static synchronized final native int dpopen(String name, int omode, int bnum);
  private static synchronized final native int dpclose(int index);
  private static synchronized final native int dpput(int index, byte[] key, int ksiz,
                                                     byte[] val, int vsiz, int dmode);
  private static synchronized final native int dpout(int index, byte[] key, int ksiz);
  private static synchronized final native byte[] dpget(int index, byte[] key, int ksiz,
                                                        int start, int max);
  private static synchronized final native int dpvsiz(int index, byte[] key, int ksiz);
  private static synchronized final native int dpiterinit(int index);
  private static synchronized final native byte[] dpiternext(int index);
  private static synchronized final native int dpsetalign(int index, int align);
  private static synchronized final native int dpsync(int index);
  private static synchronized final native int dpoptimize(int index, int bnum);
  private static synchronized final native String dpname(int index);
  private static synchronized final native int dpfsiz(int index);
  private static synchronized final native int dpbnum(int index);
  private static synchronized final native int dpbusenum(int index);
  private static synchronized final native int dprnum(int index);
  private static synchronized final native int dpwritable(int index);
  private static synchronized final native int dpfatalerror(int index);
  private static synchronized final native int dpremove(String name);
}



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