Re: [PATCH] connected.c: reprepare packs for corner cases

From: Jonathan Tan <jonathantanmy@google.com>
Date: Mar 12, 2020, 16:39 UTC
Message-ID: <20200312163939.176298-1-jonathantanmy@google.com>
In-Reply-To: <pull.579.git.1584027403779.gitgitgadget@gmail.com>

Show 7 quoted lines

> Placing a reprepare_packed_git() call inside chck_connected() before
> looping through the packed_git list seems like the safest way to
> avoid this issue in the future. While reprepare_packed_git() does
> another scan of the pack directory, it is not terribly expensive as
> long as we do not run it in a loop. We check connectivity only a
> few times per command, so this will not have a meaningful performance
> impact. In exchange, we get extra safety around this check.

This also means that check_connected() now does the equivalent of reprepare_packed_git() in both its branches (the rev-list one, which spawns a new process and thus rereads the pack directory, and the fast one). This will at least help callers to reason about its behavior more simply, so it sounds like a good change to me.

>     I included how I found this (integrating v2.26.0-rc0 into Scalar), but I
>     am able to reproduce it on my Linux machine using real fetches from
>     github.com. I'm not sure why I was unable to reproduce the issue in test
>     cases using the file:// URLs or the HTTP tests.

If you remember how to reproduce it using real fetches from github.com, could you give us reproduction steps?

Thanks for attempting to reproduce it in a test script.

Show 15 quoted lines

> diff --git a/connected.c b/connected.c
> index 7e9bd1bc622..ac52b07b474 100644
> --- a/connected.c
> +++ b/connected.c
> @@ -61,7 +61,11 @@ int check_connected(oid_iterate_fn fn, void *cb_data,
>  		 * object is a promisor object. Instead, just make sure we
>  		 * received, in a promisor packfile, the objects pointed to by
>  		 * each wanted ref.
> +		 *
> +		 * Before checking for promisor packs, be sure we have the
> +		 * latest pack-files loaded into memory.
>  		 */
> +		reprepare_packed_git(the_repository);
>  		do {
>  			struct packed_git *p;

The code itself looks good to me.