Re: Do porcelain command require lock management?

From: brian m. carlson <sandals@crustytoothpaste.net>
Date: Oct 25, 2020, 23:02 UTC
Message-ID: <20201025230203.GH860779@camp.crustytoothpaste.net>
In-Reply-To: <20201024144637.cvwa22f2y4tvfn4z@chatter.i7.local>

On 2020-10-24 at 14:46:37, Konstantin Ryabitsev wrote:

Show 12 quoted lines

> Hello:
> 
> A script I'm writing performs a succession of porcelain commands to
> create a commit in a bare git repository:
> 
> git hash-object
> git mktree
> git commit-tree
> git update-ref
> 
> Do I need to manage external locking around these commands to avoid any
> concurrency problems, or will git take care of that?

I'm almost certain that Git will do the same locking and object creation semantics that it does in porcelain commands as in the plumbing commands you're using. For example, I happen to know that all loose object creation goes through one function, which should gracefully handle concurrent accesses. Git is in general safe against concurrent accesses and is designed not to lose or corrupt data in this case.

However, I will point out that ref updates may conflict and if so, Git will fail instead of waiting. So while your repository will remain consistent and won't experience corruption, that doesn't mean that all operations will complete successfully. Some sort of retry mechanism or other error handling will probably be warranted.

-- 
brian m. carlson (he/him or they/them)
Houston, Texas, US