From: Herbert Xu <herbert@gondor.apana.org.au>
To: "C. McEnroe" <june@causal.agency>
Cc: dash@vger.kernel.org
Subject: Re: [PATCH v2] Cache the expanded prompt for editline
Date: Wed, 13 Jan 2021 17:18:02 +1100 [thread overview]
Message-ID: <20210113061802.GA6215@gondor.apana.org.au> (raw)
In-Reply-To: <20201223210257.78887-1-june@causal.agency>
C. McEnroe <june@causal.agency> wrote:
> Previously, the prompt would be expanded every time editline called the
> getprompt callback. I think the code may have been written assuming that
> editline only calls getprompt once per prompt, but it may actually call
> it many times, for instance every time you type backspace. This results
> not only in slower editing from expanding complex prompts repeatedly, it
> also consumes more and more stack memory each time getprompt is called.
> This can be seen by setting PS1 to some command substitution, typing
> many characters at the prompt, then holding backspace and observing
> memory usage. Thankfully all this stack memory is freed between prompts
> by the stackmark calls around el_gets.
>
> This change causes prompt expansion to always happen in the setprompt
> call, as it would when editline is disabled, and a cached copy of the
> prompt is saved for getprompt to return every time editline calls it.
> Since getprompt is no longer doing expansion, the stackmark calls
> surrounding el_gets can be removed.
> ---
>
> v2: Missed adding breaks when replacing returns with assignments.
What if someone actually wanted the prompt to change?
Cheers,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
next prev parent reply other threads:[~2021-01-13 6:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-23 19:47 [PATCH] Cache the expanded prompt for editline C. McEnroe
2020-12-23 21:02 ` [PATCH v2] " C. McEnroe
2021-01-13 6:18 ` Herbert Xu [this message]
2021-01-14 15:43 ` June Bug
2021-01-14 20:12 ` Herbert Xu
2021-01-14 20:22 ` June Bug
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