[jboss-jira] [JBoss JIRA] (JGRP-1771) Replace Exposed{Input, Output}Stream with ByteArray{Input, Output}Stream

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1771?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12943094#comment-12943094 ] 

Bela Ban commented on JGRP-1771:
--------------------------------

All relevant methods to read from and write to byte buffers will be defined in org.jgroups.util.Bits, similar to java.nio.Bits. This is only needed for *byte arrays* as *ByteBuffers* already contains methods to do that.

h5. Re endian-ness
Java uses the big-endian format all the time, and since JGroups does not have to communicate with non-Java processes, we'll ignore endian-ness for the time being. (Note that ByteBuffer does *not* ignore endian-ness).

Shift operators ({{<<}} {{>>}}) defined by Java and used in Bits don't simply shift left or right, but they shift towards the MSB ({{<<}}) and LSB ({{>>}}) respectively, so the result is the same in little or big endian systems, and that's why communication between processes on different architectures works in Java.
                
> Replace Exposed{Input,Output}Stream with ByteArray{Input,Output}Stream
> ----------------------------------------------------------------------
>
>                 Key: JGRP-1771
>                 URL: https://issues.jboss.org/browse/JGRP-1771
>             Project: JGroups
>          Issue Type: Enhancement
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>             Fix For: 3.5
>
>
> Currently, when reading a message, we create an ExposedByteArrayInputStream and a DataInputStream on top of it. Then we read the message or message list off of the DataInputStream.
> The problem is that DataInputStream creates an 80 byte buffer for every creation, and also an array of 80 chars (additional 160 bytes + array header + pointer).
> Same thing for sending a message or message list.
> SOLUTION:
> * Create a ByteArrayInputStream which implements DataInput and works by reading from the passed in byte array
> ** Eventually, when switching to NIO.2, use a ByteBufferInputStream which works off of NIO ByteBuffers instead of byte arrays
> *** Possibly replace readFrom(DataInput) with readFrom(Buffer) where Buffer implements reading from an NIO ByteBuffer (and possibly also from a simple byte array). Ditto for sending.
> * Similar solution for sending of messages / message lists
> * Also create the corresponding unit tests

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