seed

    fn seed(context: ?*anyopaque) callconv(.c) void {
        const rand: *Random = @ptrCast(@alignCast(context));
        const ev = rand.evented;
        ev.csprng_mutex.lockUncancelable(ev);
        defer ev.csprng_mutex.unlock();
        var buffer: [Csprng.seed_len]u8 = undefined;
        if (!ev.csprng.isInitialized()) {
            @branchHint(.unlikely);
            const cancel_protection = swapCancelProtection(ev, .blocked);
            defer assert(swapCancelProtection(ev, cancel_protection) == .blocked);
            randomSecure(ev, &buffer) catch |err| switch (err) {
                error.Canceled => unreachable, // blocked
                error.EntropyUnavailable => fallbackSeed(ev, &buffer),
            };
            ev.csprng.rng = .init(buffer);
        }
        ev.csprng.rng.fill(&buffer);
        rand.thread.csprng.rng = .init(buffer);
        rand.thread.csprng.rng.fill(rand.buffer);
        rand.buffer.len = 0;
    }