Lock the rebuild, not the read

When a hot cache key expires on a busy page, every request that misses runs the same slow query at the same time. The lock goes around the rebuild only; reads stay lock-free.

$report = Cache::get('report') ?? Cache::lock('report:build', 10)->block(5, function () {
    return Cache::remember('report', 3600, fn () => Report::build());
});

The first request takes the lock and rebuilds. The others block for up to five seconds, then run Cache::remember, which finds the fresh value and returns it without a second rebuild.

Use it when the rebuild costs more than a few hundred milliseconds. For a cheap key the lock is just overhead.