Improve gateway scheduling and runtime admission

apps/aether-gateway/src/clock.rs

@@ -1,5 +1,8 @@
+use std::sync::atomic::{AtomicU64, Ordering};
 use std::time::{SystemTime, UNIX_EPOCH};
 
+static REQUEST_DISTRIBUTION_COUNTER: AtomicU64 = AtomicU64::new(0);
+
 pub(crate) fn current_unix_secs() -> u64 {
     SystemTime::now()
         .duration_since(UNIX_EPOCH)
@@ -13,3 +16,9 @@ pub(crate) fn current_unix_ms() -> u64 {
         .unwrap_or_default()
         .as_millis() as u64
 }
+
+pub(crate) fn request_distribution_seed() -> u64 {
+    let now_ms = current_unix_ms();
+    let counter = REQUEST_DISTRIBUTION_COUNTER.fetch_add(1, Ordering::Relaxed);
+    now_ms.rotate_left(21) ^ counter
+}