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Wed, 18 Sep 2024 00:31:25 -0400 (EDT) Received: by vm-mail (OpenSMTPD) with ESMTPSA id 89d7c03f (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Wed, 18 Sep 2024 04:31:05 +0000 (UTC) Date: Wed, 18 Sep 2024 06:31:25 +0200 From: Patrick Steinhardt To: karthik nayak Cc: git@vger.kernel.org Subject: Re: [PATCH 0/3] reftable: graceful concurrent writes Message-ID: References: Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Sep 17, 2024 at 11:26:58AM -0700, karthik nayak wrote: > Patrick Steinhardt writes: > > > Hi, > > > > the reftable backend cannot properly handle concurrent writes due to two > > reasons: > > > > - It will bail out immediately when it sees a locked "tables.list" > > file. This is being addressed by introducing a configurable locking > > timeout, similar to how we have it for both loose and packed refs. > > > > - It will bail out when it notices that its stack is out-of-date after > > having locked the "tables.list" file. This is addressed by reloading > > the stack as requested after locking it, which is fine because our > > transactional API would verify queued ref updates against their > > expected state after the lock was acquired anyway. > > > > So with this patch series we can now spawn concurrent writers and they > > are expected to succeed, which is demonstrated by the test added by the > > last patch. > > > > I only had a comment in the first commit. The rest two look good to me. > I do wonder if we really need a flag? But that's just a nit. I didn't carefully vet all locations where we could pass that flag, so right now we only pass it in a single location. Also, we need to keep in mind that this is library code: even if we had converted all callsites to pass the new flag I still it's a sensibe thing to wish for to disable the automatic refresh and abort instead. Thanks for your review! Patrick