From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Thu, 24 Feb 2022 16:38:17 GMT
Subject: Re: [PATCH v5 26/30] fsmonitor--daemon: periodically truncate list of modified files
Message-ID: <nycvar.QRO.7.76.6.2202241736560.11118@tvgsbejvaqbjf.bet>
In-Reply-To: <19993c130d22b1f5f7beaee1a23ac2d6b377fec3.1644612979.git.gitgitgadget@gmail.com>

Hi Jeff,

On Fri, 11 Feb 2022, Jeff Hostetler via GitGitGadget wrote:

> From: Jeff Hostetler <jeffhost@microsoft.com>
>
> Teach fsmonitor--daemon to periodically truncate the list of
> modified files to save some memory.
>
> Clients will ask for the set of changes relative to a token that they
> found in the FSMN index extension in the index.  (This token is like a
> point in time, but different).  Clients will then update the index to
> contain the response token (so that subsequent commands will be
> relative to this new token).
>
> Therefore, the daemon can gradually truncate the in-memory list of
> changed paths as they become obsolete (older than the previous token).
> Since we may have multiple clients making concurrent requests with a
> skew of tokens and clients may be racing to the talk to the daemon,
> we lazily truncate the list.
>
> We introduce a 5 minute delay and truncate batches 5 minutes after
> they are considered obsolete.

I tried to poke holes into this strategy for a while, but failed whichever
way I looked. Meaning: I am now convinced that this strategy is sound.

Thanks,
Dscho