From: Jonathan Nieder <jrnieder@gmail.com>
Date: Tue, 12 Oct 2010 23:03:44 GMT
Subject: Re: [PATCH 7/7] svn-fe: Use the --report-fd feature
Message-ID: <20101012230344.GH15587@burratino>
In-Reply-To: <AANLkTikxsP_DV2Tjwk9vNi1WZFFiFEjQjCjhcbc5FETf@mail.gmail.com>

Sverre Rabbelier wrote:
> On Tue, Oct 12, 2010 at 15:50, David Barr <david.barr@cordelta.com> wrote:

>> On one hand, this makes the interface much uglier.
>
> Can you quantify this? What does it make uglier, and why?

| -svnadmin dump --incremental REPO | svn-fe [url] | git fast-import
| +mkfifo backchannel &&
| +svnadmin dump --incremental REPO |
| +	svn-fe [url] 3<backchannel |
| +	git fast-import --report-fd=3 3>backchannel

The caller has to take care of backflow of data.  Even if the
"cat" command were never used, at least 3>/dev/null would be
necessary to avoid fast-import waiting forever for the frontend
to read from it.

One way to work around this would be for svn-fe to launch fast-import
itself.  The main downside is that that would require a way to
configure how fast-import is to be launched (for use with other
vcs-fast-import backends and in even stranger scenarios).