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

From: Derrick Stolee <stolee@gmail.com>
Date: Mar 12, 2020, 17:34 UTC
Message-ID: <fea393f7-de8a-73a3-6139-aa1f6a78089b@gmail.com>
In-Reply-To: <20200312163939.176298-1-jonathantanmy@google.com>

On 3/12/2020 12:39 PM, Jonathan Tan wrote:

Show 21 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?

Sure. Run `git init`, then replace the `.git/config` file with this:

[core]
        repositoryformatversion = 1
        filemode = false
        bare = false
        logallrefupdates = true
        symlinks = false
        ignorecase = true
        repositoryFormat = 1
[protocol]
        version = 1
[remote "origin"]
        url = https://github.com/derrickstolee/TreeSearch
        fetch = +refs/heads/*:refs/remotes/origin/*
        promisor = true
        partialclonefilter = blob:none
[branch "master"]
        remote = origin
        merge = refs/heads/master

then run "git fetch origin". I purposefully put a very small repo that I have laying around, but this repros with git/git.

Thanks, -Stolee