db.java

来自「minibase diskmanger buffermanger」· Java 代码 · 共 345 行

package diskmgr;

import java.io.*;
import bufmgr.*;
import global.*;


public class DB implements GlobalConst {
  
	/** the number of bit in one page
	 */
	private static final int bits_per_page = MINIBASE_PAGESIZE * 8;
  
	/** the database file
	 */
	private RandomAccessFile fp;

	/** total number of page in the database file
	 */
	private int num_pages;

	/** name of the database file
	 */
	private String name;


	/** Functions to return some characteristics of the database.
	 */
	public String db_name() {
		return name;
	} // end of db_name


	public int db_num_pages() {
		return num_pages;
	} // end of db_num_pages


	public int db_page_size() {
		return MINIBASE_PAGESIZE;
	} // end of db_page_size

  
	/** default constructor.
	 */
	public DB() {
	} // end of DB


	/** DB Constructors.
	 * Create a database with the specified number of pages where the page
	 * size is the default page size.
	 *
	 * @param name DB name
	 * @param num_pages number of pages in DB
	 *
	 * @exception IOException I/O errors
	 * @exception InvalidPageNumberException invalid page number
	 * @exception FileIOException file I/O error
	 * @exception DiskMgrException error caused by other layers
	 */
	public void openDB(String fname, int num_pgs)
		throws IOException, InvalidPageNumberException, FileIOException, 
		       DiskMgrException
	{

		// type your code here
		// Note: readability of your code will be considered during marking

	} // end of openDB
  
  
	/** Open the database with the given name.
	 *
	 * @param name DB_name
	 *
	 * @exception IOException I/O errors
	 * @exception FileIOException file I/O error
	 * @exception InvalidPageNumberException invalid page number
	 * @exception DiskMgrException error caused by other layers
	 */
	public void openDB(String fname)
		throws IOException, InvalidPageNumberException, FileIOException, 
		       DiskMgrException 
	{

		// type your code here
		// Note: readability of your code will be considered during marking

	} // end of openDB
  
  
	/** Close DB file.
	 * @exception IOException I/O errors.
	 */
	public void closeDB()
		throws IOException
	{
		fp.close();
	} // end of closeDB
  
  
	/** Destroy the database, removing the file that stores it. 
	 * @exception IOException I/O errors.
	 */
	public void DBDestroy() 
		throws IOException
	{
		fp.close();

		File DBfile = new File(name);
		DBfile.delete();
	} // end of DBDestroy
  
  
	/** Allocate a set of pages where the run size is taken to be 1 by default.
	 *  Gives back the page number of the first page of the allocated run.
	 *  with default run_size =1
	 *
	 * @param start_page_num page number to start with 
	 *
	 * @exception OutOfSpaceException database is full
	 * @exception InvalidRunSizeException invalid run size 
	 * @exception InvalidPageNumberException invalid page number
	 * @exception FileIOException DB file I/O errors
	 * @exception IOException I/O errors
	 * @exception DiskMgrException error caused by other layers
	 */
	public void allocate_page(PageId start_page_num)
		throws OutOfSpaceException, InvalidRunSizeException, 
		       InvalidPageNumberException, FileIOException, 
		       DiskMgrException, IOException
	{
		allocate_page(start_page_num, 1);
	} // allocate_page
  
  
	/** user specified run_size
	 *
	 * @param start_page_num the starting page id of the run of pages
	 * @param run_size the number of page need allocated
	 *
	 * @exception OutOfSpaceException No space left
	 * @exception InvalidRunSizeException invalid run size 
	 * @exception InvalidPageNumberException invalid page number
	 * @exception FileIOException file I/O error
	 * @exception IOException I/O errors
	 * @exception DiskMgrException error caused by other layers
	 */
	public void allocate_page(PageId start_page_num, int run_size)
		throws OutOfSpaceException, InvalidRunSizeException, 
		       InvalidPageNumberException, FileIOException, 
		       DiskMgrException, IOException
	{

		// type your code here
		// Note: readability of your code will be considered during marking

	} // end of allocate_page
  
  
	/** Deallocate a set of pages starting at the specified page number
	 *  with run size = 1
	 *
	 * @param start_page_num the start pageId to be deallocate
	 * @param run_size the number of pages to be deallocated
	 *
	 * @exception InvalidRunSizeException invalid run size 
	 * @exception InvalidPageNumberException invalid page number
	 * @exception FileIOException file I/O error
	 * @exception IOException I/O errors
	 * @exception DiskMgrException error caused by other layers
	 * 
	 */
	public void deallocate_page(PageId start_page_num)
		throws InvalidRunSizeException, InvalidPageNumberException, 
		       IOException, FileIOException, DiskMgrException
	{
		deallocate_page(start_page_num, 1);
	} // end of deallocate_page
  
  
	/** Deallocate a set of pages starting at the specified page number and
	 * a run size can be specified.
	 *
	 * @param start_page_num the start pageId to be deallocate
	 * @param run_size the number of pages to be deallocated
	 * 
	 * @exception InvalidRunSizeException invalid run size 
	 * @exception InvalidPageNumberException invalid page number
	 * @exception FileIOException file I/O error
	 * @exception IOException I/O errors
	 * @exception DiskMgrException error caused by other layers
	 */
	public void deallocate_page(PageId start_page_num, int run_size)
		throws InvalidRunSizeException, InvalidPageNumberException, 
		       IOException, FileIOException, DiskMgrException
	{

		// type your code here
		// Note: readability of your code will be considered during marking

	} // deallocate_page
  
  
	/** Adds a file entry to the header page(s).
	 *
	 * @param fname file entry name
	 * @param start_page_num the start page number of the file entry
	 *
	 * @exception FileNameTooLongException invalid file name (too long)
	 * @exception InvalidPageNumberException invalid page number
	 * @exception InvalidRunSizeException invalid DB run size
	 * @exception DuplicateEntryException entry for DB is not unique
	 * @exception OutOfSpaceException database is full
	 * @exception FileIOException file I/O error
	 * @exception IOException I/O errors
	 * @exception DiskMgrException error caused by other layers
	 */
	public void add_file_entry(String fname, PageId start_page_num)
		throws FileNameTooLongException, InvalidPageNumberException, 
		       InvalidRunSizeException, DuplicateEntryException,
		       OutOfSpaceException, FileIOException, IOException, 
		       DiskMgrException 
	{

		// type your code here
		// Note: readability of your code will be considered during marking

	} // end of add_file_entry
  
  
	/** Delete the entry corresponding to a file from the header page(s).
	 *
	 * @param fname file entry name
	 *
	 * @exception FileEntryNotFoundException file does not exist
	 * @exception FileIOException file I/O error
	 * @exception IOException I/O errors
	 * @exception InvalidPageNumberException invalid page number
	 * @exception DiskMgrException error caused by other layers
	 */
	public void delete_file_entry(String fname)
		throws FileEntryNotFoundException, IOException, FileIOException,
		       InvalidPageNumberException, DiskMgrException
	{

		// type your code here
		// Note: readability of your code will be considered during marking

	} // end of delete_file_entry
  
  
	/** Get the entry corresponding to the given file.
	 *
	 * @param name file entry name
	 *
	 * @exception IOException I/O errors
	 * @exception FileIOException file I/O error
	 * @exception InvalidPageNumberException invalid page number
	 * @exception DiskMgrException error caused by other layers
	 */
	public PageId get_file_entry(String name)
		throws IOException, FileIOException, InvalidPageNumberException, 
		       DiskMgrException
	{

		// type your code here
		// Note: readability of your code will be considered during marking

		return null;
	} // end of get_file_entry
  
  
	/** Read the contents of the specified page into a Page object
	 *
	 * @param pageno pageId which will be read
	 * @param apage page object which holds the contents of page
	 *
	 * @exception InvalidPageNumberException invalid page number
	 * @exception FileIOException file I/O error
	 * @exception IOException I/O errors
	 */
	public void read_page(PageId pageno, Page apage)
		throws InvalidPageNumberException, FileIOException, IOException
	{

		// type your code here
		// Note: readability of your code will be considered during marking

	} // end of read_page
  
  
	/** Write the contents in a page object to the specified page.
	 *
	 * @param pageno pageId will be wrote to disk
	 * @param apage the page object will be wrote to disk
	 *
	 * @exception InvalidPageNumberException invalid page number
	 * @exception FileIOException file I/O error
	 * @exception IOException I/O errors
	 */
	public void write_page(PageId pageno, Page apage)
		throws InvalidPageNumberException, FileIOException, IOException
	{

		// type your code here
		// Note: readability of your code will be considered during marking

	} // end of write_page
  
  
	/** short cut to access the pinPage function in bufmgr package.
	 * 
	 * @see bufmgr.pinPage
	 */
	private void pinPage(PageId pageno, Page page, boolean emptyPage)
		throws DiskMgrException
	{
		try {
			SystemDefs.JavabaseBM.pinPage(pageno, page, emptyPage);
		}
		catch(Exception e) {
			throw new DiskMgrException(e, "DB.java:pinPage() failed");
		}
	} // end of pinPage

  
	/** short cut to access the unpinPage function in bufmgr package.
	 * 
	 * @see bufmgr.unpinPage
	 */
	private void unpinPage(PageId pageno, boolean dirty)
		throws DiskMgrException
	{
		try {
			SystemDefs.JavabaseBM.unpinPage(pageno, dirty);
		}
		catch(Exception e) {
			throw new DiskMgrException(e, "DB.java:unpinPage() failed");
		}
	} // end of unpinPage
}