$ curl -s https://cache.nixos.org/gypp7g48p2fcpjx952i84dhw4ak95np1.narinfo --show-headers
HTTP/2 404 
server: Varnish
retry-after: 0
content-type: text/plain
accept-ranges: bytes
date: Mon, 22 Jun 2026 06:06:44 GMT
via: 1.1 varnish
x-served-by: cache-vie6368-VIE
x-cache: MISS
x-cache-hits: 0
access-control-allow-origin: *
content-length: 3

404⏎                                                                                                          

Also this one, it was 7 days old commit

8c14fa3ccacd..ea68a74f45ad  nixpkgs-26.05-darwin

In reply to @vcunat:matrix.org
It's certainly fine not to cache those, as long as it doesn't cost us much.

We do get charged for 404s and 200s just the same.

Idk what the ratio between uncached 404s and 200s is. We can look this up in fastly.

Caching 404s definitely saves money. But idk how much.

But we currently don't cache them exactly so that we don't have read after write inconsistencies.

        let now = jiff::Timestamp::now().as_second();
        let jobs_in_last_30s_start = self.stats.jobs_in_last_30s_start.load(Ordering::Relaxed);
        let jobs_in_last_30s_count = self.stats.jobs_in_last_30s_count.load(Ordering::Relaxed);

        // ensure that we dont submit more than 4 jobs in 30s
        if now <= (jobs_in_last_30s_start + 30)
            && jobs_in_last_30s_count >= 4
            // ensure that we havent already finished some of them, because then its fine again
            && self.stats.get_current_jobs() >= 4
        {
            return false;
        } else if now > (jobs_in_last_30s_start + 30) {
            // reset count
            self.stats
                .jobs_in_last_30s_start
                .store(0, Ordering::Relaxed);
            self.stats
                .jobs_in_last_30s_count
                .store(0, Ordering::Relaxed);
        }