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From Nicolas Lalevée <nicolas.lale...@hibnet.org>
Subject Re: Log Flushing
Date Tue, 19 Apr 2011 15:56:19 GMT

Le 19 avr. 2011 à 16:42, Antoine Levy-Lambert a écrit :

> On 4/19/2011 8:29 AM, Nicolas Lalevée wrote:
>> Thank you very much for the pointers. The patch for the bug report #50507 seems to
tackle the streaming issue.
>> 
>> I guess that in Ant we always want to see the log by line, rather than with usual
unix tools where the output is streamed. With unix tools, streaming is useful when pipelining
commands. I guess we never do that with Ant.
>> 
>> In the suggested patch, line ending "awareness" is only enabled when we merge both
the standard output stream and the error one.
> I think the line ending awareness is enabled by the patch in the case when there is no
redirection of either standard err or standard out to files or properties. I do not think
it is the same as merging standard out and standard err, except that if a line of standard
err is produced by the executable between two lines of standard out it will be visible that
way.
> 
> If one of the two stream, out and err, is not redirected to a file or copied to a property,
lines should still be preserved, so other use cases should be changed functionally if currently
they break lines.

Well, if the two streams are not merged, then there should not be any issue then, as each
stream will push things into its own "thing". "thing" being a file, or a socket, or even a
wrapped standard stream. In that last case of the "wrapped standard stream", it is then the
responsibility of the wrapper to properly output it I think.

But as you pointed to me in the chat, there is indeed some issue with the LineOrientedOutputStream
which is quite sensible with too many flush. It will create a new line on each flush.
I then suggest to make the LineOrientedOutputStream#flush function do nothing, which will
fix Conor's bug.
And the patch in #50507 will actually just fix the bug #50507.

>> So if somebody really want to do output stream pipelining, he most probably doesn't
want mixing these streams. For such used case, the best approach would then be to extends
the ExecTask and override createHandler() to implement its proper pipelining.

I was talking about doing stuff like this:
$ svn status | grep -e "^\?" | cut -d " " -f 8

But looking closer we do have such things in Ant with the redirector stuff. So forget what
I wrote.

Nicolas


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