Re: [1/5] Parsing code in revision.h

From: Linus Torvalds <torvalds@osdl.org>
Date: Apr 17, 2005, 20:06 UTC
Message-ID: <Pine.LNX.4.58.0504171254500.7211@ppc970.osdl.org>
In-Reply-To: <Pine.LNX.4.58.0504171253030.7211@ppc970.osdl.org>

On Sun, 17 Apr 2005, Linus Torvalds wrote:

Show 5 quoted lines

> 
> Yes. I'm not opposed to yours, I was just opposed to some of the things 
> around it you did, so I wrote mine as a kind of place-holder. I'll happily 
> take patches to turn it from a rally simple and stupid one into a more 
> polished version.

Btw, before I forget - I did have another reason. I actually think that the date is potentially a lot more important than "how many parents deep".

In particular, it's entirely possible that the top of my head might be a veru recent merge that merges with a small fix relative to a very old parent (making that old parent be just two hops away from the head), while the thing I want to merge might also have that old parent (for similar reasons) as a relatively "close" parent from a pure link-counting standpoint.

The reason I bring this up is that quite often people end up basing their work on a specific release version, so a merge (especially in specialized areas) may thus bring such an old parent pretty close to the head, and it can actually be quite possible (indeed probable) that such a parent ends up being a common parent.

However, it can easily be a very _bad_ parent.

In ascii barfic:

	        ----------------------- patch ---------
	       /                                        \
	      /                                          \
	- old release -- ... lots of development .. -----HEAD
	     \  \
	      \  \
	       \  ---------------------patch-- MERGE-HEAD      
	        \                             /
		  .. lots of development ..  /

it looks like "old release" is pretty close to both HEAD and MERGE-HEAD, right?

But that's just an artifact of the fact that they both had a trivial merge against some older code, and if the two "lots of development" things have ever done an earlier merge, there's quite possibly a _much_ better common parent there somewhere.

I dunno.

		Linus