Updating existing JDK code to use InputStream.transferTo()

Remi Forax forax at univ-mlv.fr
Wed May 13 21:45:10 UTC 2015

On 05/13/2015 05:29 PM, Pavel Rappo wrote:
>> It now can be reviewed as usual at:
>> 	http://cr.openjdk.java.net/~prappo/8080272/webrev.00/
>> Feel free to review. Thanks.
> Let me start then.
> 1. I've seen several cases where current behaviour
>      while ((n = in.read(buffer)) > 0)
>                                  ~~~
> has been changed to
>      while ((read = this.read(buffer, 0, TRANSFER_BUFFER_SIZE)) >= 0)
>                                                                 ~~~
> Those things jump out at you, but don't seem to be harmful, since the only case
> where:
>      java.io.InputStream.read(byte[], int off, int len)
>      java.io.InputStream#read(byte[])
> may return 0, is when len == 0. And it's never the case here. Unless, of course,
> some misbehaving implementation of InputStream is used.

The other reason to have read that returns 0 is if the underlying 
channel is in non-blocking mode.
A read on an InputStream created by Channels.newInputStream on a 
SelectableChannel may return 0
and the code will go in a loop until the SelectableChannel can read 
while(read() > 0) avoid that issue.

The other things that may be a problem with this patch is that a lot of 
codes replaced by transferTo use
either a bigger or a smaller size of buffer than transferTo.
Given that we don't know if the buffer size is something important for a 
code or if the buffer size can be changed, i think it's better to split 
this patch in several parts and to send each parts to the right mailing 


More information about the core-libs-dev mailing list