edu.rit.mp.buf

Class EmptyByteBuf

java.lang.Object

edu.rit.mp.Buf

edu.rit.mp.ByteBuf

edu.rit.mp.buf.EmptyByteBuf

public class EmptyByteBuf
extends ByteBuf

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

Constructor Summary

Constructors

Constructor and Description
EmptyByteBuf() Construct a new empty byte buffer.

Method Summary

Modifier and Type	Method and Description
void	copy(Buf theSrc) Copy items from the given buffer to this buffer.
byte	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, byte item) Store the given item in this buffer.

Methods inherited from class edu.rit.mp.ByteBuf

buffer, buffer, buffer, buffer, buffer, buffer, colSliceBuffer, colSliceBuffers, 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

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

Constructor Detail

EmptyByteBuf

public EmptyByteBuf()

Construct a new empty byte buffer.

Method Detail

get

public byte 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 ByteBuf

Parameters:

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

Returns:

Item at index i.

put

public void put(int i,
                byte 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 ByteBuf

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 ByteBuf

Parameters:

theSrc - Source of items to copy into this buffer.

Throws:

java.lang.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:

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