edu.rit.mp.buf
Class EmptyShortBuf

java.lang.Object
  edu.rit.mp.Buf
      edu.rit.mp.ShortBuf
          edu.rit.mp.buf.EmptyShortBuf

public class EmptyShortBuf
extends ShortBuf

Class EmptyShortBuf provides a short buffer that contains no items for messages using the Message Protocol (MP). When a message is sent from an EmptyShortBuf, the message item type is short and the message length is 0. When a message is received into an EmptyShortBuf, the message item type must be short, but all items in the message are discarded.

Field Summary

Fields inherited from class edu.rit.mp.Buf

myLength

Constructor Summary

EmptyShortBuf()
Construct a new empty short buffer.

Method Summary

void	copy(Buf theSrc) Copy items from the given buffer to this buffer.
short	get(int i) Obtain the given item from this buffer.
Buf	getReductionBuf(Op op) Create a buffer for performing parallel reduction using the given binary operation.
void	put(int i, short item) Store the given item in this buffer.
protected int	receiveItems(int i, int num, ByteBuffer buffer) Receive as many items as possible from the given byte buffer to this buffer.
protected int	sendItems(int i, ByteBuffer buffer) Send as many items as possible from this buffer to the given byte buffer.

Methods inherited from class edu.rit.mp.ShortBuf

buffer, buffer, buffer, buffer, buffer, buffer, colSliceBuffer, colSliceBuffers, defaultCopy, emptyBuffer, fill, getTemporaryBuf, patchBuffer, patchBuffers, rowSliceBuffer, rowSliceBuffers, sliceBuffer, sliceBuffer, sliceBuffers, sliceBuffers

Methods inherited from class edu.rit.mp.Buf

length

Methods inherited from class java.lang.Object

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

Constructor Detail

EmptyShortBuf

public EmptyShortBuf()

Construct a new empty short buffer.

Method Detail

get

public short get(int i)

Obtain the given item from this buffer.

The get() method must not block the calling thread; if it does, all message I/O in MP will be blocked.

Specified by:

get in class ShortBuf

Parameters:

i - Item index in the range 0 .. length()-1.

Returns:

Item at index i.

put

public void put(int i,
                short item)

Store the given item in this buffer.

The put() method must not block the calling thread; if it does, all message I/O in MP will be blocked.

Specified by:

put in class ShortBuf

Parameters:

i - Item index in the range 0 .. length()-1.

item - Item to be stored at index i.

copy

public void copy(Buf theSrc)

Copy items from the given buffer to this buffer. The number of items copied is this buffer's length or theSrc's length, whichever is smaller. If theSrc is this buffer, the copy() method does nothing.

Overrides:

copy in class ShortBuf

Parameters:

theSrc - Source of items to copy into this buffer.

Throws:

ClassCastException - (unchecked exception) Thrown if theSrc's item data type is not the same as this buffer's item data type.

getReductionBuf

public Buf getReductionBuf(Op op)

Create a buffer for performing parallel reduction using the given binary operation. The results of the reduction are placed into this buffer.

Operations performed on the returned reduction buffer have the same effect as operations performed on this buffer, except whenever a source item S is put into a destination item D in this buffer, D is set to D op S, that is, the reduction of D and S using the given binary operation (rather than just setting D to S).

Specified by:

getReductionBuf in class Buf

Parameters:

op - Binary operation.

Throws:

ClassCastException - (unchecked exception) Thrown if this buffer's element data type and the given binary operation's argument data type are not the same.

sendItems

protected int sendItems(int i,
                        ByteBuffer buffer)

Send as many items as possible from this buffer to the given byte buffer.

The sendItems() method must not block the calling thread; if it does, all message I/O in MP will be blocked.

Specified by:

sendItems in class Buf

Parameters:

i - Index of first item to send, in the range 0 .. length-1.

buffer - Byte buffer.

Returns:

Number of items sent.

receiveItems

protected int receiveItems(int i,
                           int num,
                           ByteBuffer buffer)

Receive as many items as possible from the given byte buffer to this buffer.

The receiveItems() method must not block the calling thread; if it does, all message I/O in MP will be blocked.

Specified by:

receiveItems in class Buf

Parameters:

i - Index of first item to receive, in the range 0 .. length-1.

num - Maximum number of items to receive.

buffer - Byte buffer.

Returns:

Number of items received.