Re: [PATCH 0/2] strbuf: improve API

From: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Date: Jun 2, 2016, 12:58 UTC
Message-ID: <vpqwpm7n3wx.fsf@anie.imag.fr>
In-Reply-To: <5750147C.5060609@alum.mit.edu>

Michael Haggerty <mhagger@alum.mit.edu> writes:

> 1. The amount of added code complexity is small and quite
>    encapsulated.

Actually, STRBUF_OWNS_MEMORY can even be seen as a simplification if done properly: we already have the case where the strbuf does not own the memory with strbuf_slopbuf. I already pointed places in strbuf_grow() which could be simplified after the patch. Re-reading the code it seems at lesat the call to strbuf_grow(sb, 0); in strbuf_detach becomes useless. The same in strbuf_attach() probably is, too.

So, the final strbuf.[ch] code might not be "worse" that the previous.

I'm unsure about the complexity of the future code using the new API. I don't forsee cases where using the new API would lead to a high maintenance cost, but I don't claim I considered all possible uses.

Show 5 quoted lines

> 2. The ability to use strbufs without having to allocate memory might
>    make enough *psychological* difference that it encourages some
>    devs to use strbufs where they would otherwise have done manual
>    memory management. I think this would be a *big* win in terms of
>    potential bugs and security vulnerabilities avoided.

Note that this can also be seen as a counter-argument, since it may psychologically encourage people to micro-optimize code and use contributors/reviewers neurons to spend time on "shall this be on-stack or malloced?".

I think we already have a tendency to micro-optimize non-critical code too much in Git's codebase, so it's not necessarily a step in the right direction.

In conclusion, I don't have a conclusion, sorry ;-).

-- 
Matthieu Moy
http://www-verimag.imag.fr/~moy/