Kevin Guthrie

make Lru::shard_weight a lock-free read Add a per-shard atomic shadow of total weight (shard_weights: [AtomicUsize; N]) maintained alongside the existing global weight counter at every weight-mutating site (admit, increment_weight, evict_shard_at, remove, insert_tail). Rewrite Lru::shard_weight() to read from the shadow with a Relaxed load instead of acquiring the shard's RwLock to read the LruUnit::used_weight field. This mirrors the pattern already established for shard_lens/shard_len(). Like shard_len(), the same 'best-effort, no cross-thread ordering' caveat applies: the sum of shard_weight(i) is not guaranteed to equal weight() at any single instant, since the global and per-shard atomics are updated independently with Relaxed ordering. Motivation: callers (eviction-balance heuristics, observability) that want to scan all N shards every few seconds should not pay N brief read-lock acquisitions when an atomic shadow is cheap enough to maintain on the write path. Adds a single-threaded regression test verifying the shadow stays consistent with the truth across all five weight-mutating paths.

Add a system for specifying and using service-level dependencies

Add a mechanism for signalling between old and new processes when doing graceful upgrades

Allow server bootstrapping to take place in the context of services with dependents and dependencies

Fix flaky tests: test_tls_psk, test_conn_timeout, test_1xx_caching, listener port collisions test_conn_timeout / test_conn_timeout_with_offload: Replace 192.0.2.1 (TEST-~~~) with a bound-but-not-listening local socket via the new timeout_socket() helper in utils::for_testing. Because listen() is never called, the kernel silently drops SYN packets, guaranteeing a real ConnectTimedout on Linux. The total_connection_timeout tests still use 192.0.2.1 (SEMI_BLACKHOLE) since they test error classification and accept ConnectNoRoute as an alternative. test_tls_psk (s2n): PskTlsServer::start() spawned a background thread with no readiness check. Use an mpsc channel to signal after TcpListener::bind so tests only proceed once the port is ready. Also make the accept loop resilient to handshake failures (continue instead of panic) so a stale probe cannot take down the server. test_1xx_caching: mock_1xx_server used fixed ports (6151/6152) and sleep(100ms) for readiness. Refactored to spawn_mock_1xx_server which binds to port 0 (OS-assigned) and signals readiness via a oneshot channel after bind. Eliminates AddrInUse from TIME_WAIT and sleep races. test_listen_tcp / test_listen_tcp_ipv6_only: Hardcoded ports 7100-7102 collided across parallel CI test jobs. Switch to port 0 with the new ListenerEndpoint::local_addr() / Listener::local_addr() methods to discover the actual bound port.

Fix listen fds not inherited during bootstrap_as_a_service graceful upgrade When bootstrap_as_a_service is enabled, listen_fds() was called to snapshot the fd table before BootstrapService had run, always returning None. Services would then bind fresh sockets instead of inheriting the old process's fds, breaking graceful upgrades. Fix this by eagerly allocating the ListenFds table in Bootstrap::new() so it is non-optional and already distributed to all services before bootstrap runs. When load_fds() later receives the inherited fds from the old process, it populates the same shared table in place, making them visible to all services without any re-distribution.

Replace tokio::sync::Mutex with parking_lot::Mutex for ListenFds ListenFds only guards an in-memory fd table and a blocking send_to_sock call, neither of which benefit from an async mutex. Switch to parking_lot::Mutex and move the fd-send path in main_loop onto the blocking thread pool via spawn_blocking. Because the parking_lot lock cannot be held across bind().await in ListenerEndpointBuilder::listen(), introduce a global per-address async lock map (flurry::HashMap<String, Arc<tokio::sync::Mutex<()>>>) that serializes the check-bind-insert sequence for each address. This prevents two concurrent callers from racing to bind the same address while the ListenFds lock is released.

RUSTSEC-2026-0098 and RUSTSEC-2026-0099 fixes Bump dev-deps to pull in rustls-webpki 0.103.12.

Fix warnings for s2n tls integration

Deflake `test_bind_to_port_range_on_connect`