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From: Paul Tan <pyokagan@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Git List <git@vger.kernel.org>,
	Stefan Beller <sbeller@google.com>,
	Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: Re: [PATCH/WIP v3 07/31] am: extract patch, message and authorship with git-mailinfo
Date: Sat, 20 Jun 2015 00:15:41 +0800	[thread overview]
Message-ID: <CACRoPnQdR7qC6gH7j9_8gQUYKShLRQCr6GNtmn+XCpe9P4P-nA@mail.gmail.com> (raw)
In-Reply-To: <CAPc5daVbpB_T4cY1xvLrBKPUZw0JNMXqNAOsKE-R7NPO2nrnZA@mail.gmail.com>

On Fri, Jun 19, 2015 at 11:09 PM, Junio C Hamano <gitster@pobox.com> wrote:
> You do realize that strbuf internally does alloc/free so as a solution to
> fragmentation issue you are at the mercy of the same alloc/free, don't you?

Yes, of course, but it has the "alloc" variable to keep track of the
size of the allocated buffer, and provided that ALLOC_GROW() uses a
sensible factor to grow the buffer, it won't be calling malloc/free
that much to be a problem.

Of course, we could do the same and just add a "alloc" variable as
well and then use it with strbuf_attach()/strbuf_detach(), but at this
point why not just store it in an strbuf then and avoid the extra
"alloc" struct member?

> The primary thing I care about is to discourage callers of the API element
> am_state from touching these fields with strbuf functions. If it is char * then
> the would think twice before modifying (which would involve allocating the
> new buffer, forming the new value and assigning into it). With the fields left
> as strbuf after they are read or formed by the API (by reading by the API
> implementation from $GIT_DIR/rebase-apply/), it is too tempting to do
> strbuf_add(), strbuf_trim(), etc., without restoring the value to the original
> saying "I'm the last user of it anyway"--that is the sloppiness we can prevent
> by not leaving it as strbuf.

I don't think this is a good deterrent. If the code wanted to, it
could just use strbuf_attach()/strbuf_detach() as well, no?

I believe this kind of issue would be better solved with a big WARNING
comment and code review.

Also, there may be use cases where the user may wish to modify the
commit message/author fields. E.g., user may wish to modify the
message of the commit that results from am --continue to take into
account the conflicts that caused the am to fail.

Regards,
Paul

  parent reply	other threads:[~2015-06-19 16:16 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-18 11:25 [PATCH/WIP v3 00/31] Make git-am a builtin Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 01/31] wrapper: implement xopen() Paul Tan
2015-06-24 16:28   ` Johannes Schindelin
2015-06-24 16:59     ` Stefan Beller
2015-06-24 18:39       ` Johannes Schindelin
2015-07-01  9:41         ` Paul Tan
2015-07-01  9:53           ` Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 02/31] wrapper: implement xfopen() Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 03/31] am: implement skeletal builtin am Paul Tan
2015-06-18 20:26   ` Junio C Hamano
2015-06-19  9:56     ` Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 04/31] am: implement patch queue mechanism Paul Tan
2015-06-18 17:47   ` Stefan Beller
2015-06-18 20:43   ` Junio C Hamano
2015-06-19 12:49     ` Paul Tan
2015-06-24 14:59   ` Johannes Schindelin
2015-06-25 15:16     ` Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 05/31] am: split out mbox/maildir patches with git-mailsplit Paul Tan
2015-06-18 20:52   ` Junio C Hamano
2015-06-18 11:25 ` [PATCH/WIP v3 06/31] am: detect mbox patches Paul Tan
2015-06-18 21:02   ` Junio C Hamano
2015-06-24  8:41     ` Paul Tan
2015-06-24 15:10   ` Johannes Schindelin
2015-06-25 13:40     ` Paul Tan
2015-06-26  7:42       ` Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 07/31] am: extract patch, message and authorship with git-mailinfo Paul Tan
2015-06-18 21:10   ` Junio C Hamano
2015-06-19  9:22     ` Paul Tan
2015-06-19 16:13       ` Junio C Hamano
2015-06-24  7:54         ` Paul Tan
2015-06-24 15:59           ` Junio C Hamano
2015-06-25 11:54             ` Paul Tan
     [not found]       ` <CAPc5daVbpB_T4cY1xvLrBKPUZw0JNMXqNAOsKE-R7NPO2nrnZA@mail.gmail.com>
2015-06-19 16:15         ` Paul Tan [this message]
2015-06-19 20:12           ` Johannes Schindelin
2015-06-24 16:36   ` Johannes Schindelin
2015-06-26  8:11     ` Paul Tan
2015-06-26 20:41       ` Junio C Hamano
2015-06-18 11:25 ` [PATCH/WIP v3 08/31] am: apply patch with git-apply Paul Tan
2015-06-18 21:23   ` Junio C Hamano
2015-06-18 11:25 ` [PATCH/WIP v3 09/31] am: commit applied patch Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 10/31] am: refresh the index at start Paul Tan
2015-06-18 21:28   ` Junio C Hamano
2015-06-19  8:07     ` Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 11/31] am: refuse to apply patches if index is dirty Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 12/31] am: implement --resolved/--continue Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 13/31] am: implement --skip Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 14/31] am: implement --abort Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 15/31] am: don't accept patches when there's a session in progress Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 16/31] am: implement quiet option Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 17/31] am: exit with user friendly message on patch failure Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 18/31] am: implement am --signoff Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 19/31] cache-tree: introduce write_index_as_tree() Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 20/31] am: implement 3-way merge Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 21/31] am: --rebasing Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 22/31] am: don't use git-mailinfo if --rebasing Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 23/31] am: handle stray state directory Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 24/31] am: implement -k/--keep, --keep-non-patch Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 25/31] am: implement --[no-]message-id, am.messageid Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 26/31] am: support --keep-cr, am.keepcr Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 27/31] am: implement --[no-]scissors Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 28/31] am: pass git-apply's options to git-apply Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 29/31] am: implement --ignore-date Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 30/31] am: implement --committer-date-is-author-date Paul Tan
2015-06-18 11:25 ` [PATCH/WIP v3 31/31] am: implement -S/--gpg-sign, commit.gpgsign Paul Tan

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