iterator
Class IoBuf

java.lang.Object
  iterator.IoBuf

All Implemented Interfaces:

GlobalConst

public class IoBuf

extends java.lang.Object

implements GlobalConst

Field Summary

static int	READ_BUFFER
static int	WRITE_BUFFER

Fields inherited from interface global.GlobalConst

INVALID_PAGE, MAX_NAME, MAX_SPACE, MAXATTRNAME, MAXFILENAME, MAXINDEXNAME, MINIBASE_BUFFER_POOL_SIZE, MINIBASE_DB_SIZE, MINIBASE_DEFAULT_SHAREDMEM_SIZE, MINIBASE_MAX_TRANSACTIONS, MINIBASE_MAXARRSIZE, MINIBASE_PAGESIZE, NUMBUF

Constructor Summary

IoBuf()

Method Summary

long	flush() returns the numbers of tuples written
Tuple	Get(Tuple buf) get a tuple from current buffer,pass reference buf to this method usage:temp_tuple = tuple.Get(buf);
void	init(byte[][] bufs, int n_pages, int tSize, Heapfile temp_fd) Initialize some necessary inormation, call Iobuf to create the object, and call init to finish instantiation
void	IoBuf() Constructor - use init to initialize.
void	Put(Tuple buf) Writes a tuple to the output buffer
void	reread() if WRITE_BUFFER is true, call this mehtod to switch to read buffer.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

WRITE_BUFFER

public static final int WRITE_BUFFER

See Also:

Constant Field Values

READ_BUFFER

public static final int READ_BUFFER

See Also:

Constant Field Values

Constructor Detail

IoBuf

public IoBuf()

Method Detail

IoBuf

public void IoBuf()

Constructor - use init to initialize.

init

public void init(byte[][] bufs,
                 int n_pages,
                 int tSize,
                 Heapfile temp_fd)

Initialize some necessary inormation, call Iobuf to create the object, and call init to finish instantiation

Parameters:

n_pages - the number of pages of this buffer

tSize - the page size the size of tuple being stored here; i.e., Tuple.size()

temp_fd - the reference to a Heapfile

Put

public void Put(Tuple buf)
         throws NoOutputBuffer,
                java.io.IOException,
                java.lang.Exception

Writes a tuple to the output buffer

Parameters:

buf - the tuple written to buffer

Throws:

NoOutputBuffer - the buffer is a input bufer now

java.io.IOException - some I/O fault

java.lang.Exception - other exceptions

Get

public Tuple Get(Tuple buf)
          throws java.io.IOException,
                 java.lang.Exception

get a tuple from current buffer,pass reference buf to this method usage:temp_tuple = tuple.Get(buf);

Parameters:

buf - write the result to buf

Returns:

the result tuple

Throws:

java.io.IOException - some I/O fault

java.lang.Exception - other exceptions

flush

public long flush()
           throws java.io.IOException,
                  java.lang.Exception

returns the numbers of tuples written

Returns:

the numbers of tuples written

Throws:

java.io.IOException - some I/O fault

java.lang.Exception - other exceptions

reread

public void reread()
            throws java.io.IOException,
                   java.lang.Exception

if WRITE_BUFFER is true, call this mehtod to switch to read buffer.

Throws:

java.io.IOException - some I/O fault

java.lang.Exception - other exceptions