From: Jeff King <peff@peff.net>
To: "Martin Ågren" <martin.agren@gmail.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH v2 3/6] leak_pending: use `object_array_clear()`, not `free()`
Date: Fri, 22 Sep 2017 23:47:17 -0400 [thread overview]
Message-ID: <20170923034717.i65irpbmlxtzwo3h@sigill.intra.peff.net> (raw)
In-Reply-To: <d4df674923b0dbc5c2e232cdc56a75205653d275.1506120292.git.martin.agren@gmail.com>
On Sat, Sep 23, 2017 at 01:34:51AM +0200, Martin Ågren wrote:
> Setting `leak_pending = 1` tells `prepare_revision_walk()` not to
> release the `pending` array, and makes that the caller's responsibility.
> See 4a43d374f (revision: add leak_pending flag, 2011-10-01) and
> 353f5657a (bisect: use leak_pending flag, 2011-10-01).
>
> Commit 1da1e07c8 (clean up name allocation in prepare_revision_walk,
> 2014-10-15) fixed a memory leak in `prepare_revision_walk()` by
> switching from `free()` to `object_array_clear()`. However, where we use
> the `leak_pending`-mechanism, we're still only calling `free()`.
Thanks for digging up the history here. Reviewing those it seems clear
that doing a full object_array_clear() is the right thing.
> Use `object_array_clear()` instead. Copy some helpful comments from
> 353f5657a to the other callers that we update to clarify the memory
> responsibilities, and to highlight that the commits are not affected
> when we clear the array -- it is indeed correct to both tidy up the
> commit flags and clear the object array.
>
> Document `leak_pending` in revision.h to help future users get this
> right.
This all looks good to me. Since the main use of "leak_pending" seems to
be to clear commit marks, I have a feeling that a better API would have
been something like:
/* normal setup and use */
init_revisions(&rev);
setup_revisions(&rev, ...);
prepare_revision_walk(&rev);
while (get_revision(&rev))
...;
/* optional, but sensible if there may be other callers */
clear_commit_marks(&rev);
/* actually free any held memory */
clear_revisions(&rev);
which would imply rev_info holding onto the "old" pending list
automatically until we decommission the rev_info in the final step.
But that's obviously a much bigger change. What you have here looks like
a nice clean fix to the leak problems.
-Peff
next prev parent reply other threads:[~2017-09-23 3:47 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-20 19:47 [PATCH] diff-lib: clear `pending` object-array in `index_differs_from()` Martin Ågren
2017-09-20 20:02 ` Jeff King
2017-09-21 3:56 ` Martin Ågren
2017-09-21 4:52 ` Jeff King
2017-09-22 23:34 ` [PATCH v2 0/6] reroll ma/plugleaks; more `object_array`-fixes Martin Ågren
2017-09-22 23:34 ` [PATCH v2 1/6] builtin/commit: fix memory leak in `prepare_index()` Martin Ågren
2017-09-22 23:34 ` [PATCH v2 2/6] commit: fix memory leak in `reduce_heads()` Martin Ågren
2017-09-22 23:34 ` [PATCH v2 3/6] leak_pending: use `object_array_clear()`, not `free()` Martin Ågren
2017-09-23 3:47 ` Jeff King [this message]
2017-09-22 23:34 ` [PATCH v2 4/6] object_array: " Martin Ågren
2017-09-23 4:04 ` Jeff King
2017-09-23 9:41 ` Martin Ågren
2017-09-22 23:34 ` [PATCH v2 5/6] object_array: add and use `object_array_pop()` Martin Ågren
2017-09-23 4:27 ` Jeff King
2017-09-23 9:49 ` Martin Ågren
2017-09-23 15:47 ` Jeff King
2017-09-22 23:34 ` [PATCH v2 6/6] pack-bitmap[-write]: use `object_array_clear()`, don't leak Martin Ågren
2017-09-23 4:35 ` Jeff King
2017-09-23 4:37 ` [PATCH v2 0/6] reroll ma/plugleaks; more `object_array`-fixes Jeff King
2017-09-23 9:54 ` Martin Ågren
2017-09-23 16:13 ` Jeff King
2017-09-23 16:38 ` Jeff King
2017-09-24 19:59 ` Martin Ågren
2017-09-25 16:08 ` Jeff King
2017-10-01 15:04 ` Martin Ågren
2017-09-24 7:01 ` Junio C Hamano
2017-09-24 20:00 ` Martin Ågren
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