feat(smart-proxy): add UDP transport support with QUIC/HTTP3 routing and datagram handler relay

rust/crates/rustproxy-metrics/src/collector.rs

@@ -26,6 +26,11 @@ pub struct Metrics {
     pub total_http_requests: u64,
     pub http_requests_per_sec: u64,
     pub http_requests_per_sec_recent: u64,
+    // UDP metrics
+    pub active_udp_sessions: u64,
+    pub total_udp_sessions: u64,
+    pub total_datagrams_in: u64,
+    pub total_datagrams_out: u64,
 }
 
 /// Per-route metrics.
@@ -136,6 +141,12 @@ pub struct MetricsCollector {
     pending_http_requests: AtomicU64,
     http_request_throughput: Mutex<ThroughputTracker>,
 
+    // ── UDP metrics ──
+    active_udp_sessions: AtomicU64,
+    total_udp_sessions: AtomicU64,
+    total_datagrams_in: AtomicU64,
+    total_datagrams_out: AtomicU64,
+
     // ── Lock-free pending throughput counters (hot path) ──
     global_pending_tp_in: AtomicU64,
     global_pending_tp_out: AtomicU64,
@@ -180,6 +191,10 @@ impl MetricsCollector {
             backend_pool_hits: DashMap::new(),
             backend_pool_misses: DashMap::new(),
             backend_h2_failures: DashMap::new(),
+            active_udp_sessions: AtomicU64::new(0),
+            total_udp_sessions: AtomicU64::new(0),
+            total_datagrams_in: AtomicU64::new(0),
+            total_datagrams_out: AtomicU64::new(0),
             total_http_requests: AtomicU64::new(0),
             pending_http_requests: AtomicU64::new(0),
             http_request_throughput: Mutex::new(ThroughputTracker::new(retention_seconds)),
@@ -350,6 +365,29 @@ impl MetricsCollector {
         self.pending_http_requests.fetch_add(1, Ordering::Relaxed);
     }
 
+    // ── UDP session recording methods ──
+
+    /// Record a new UDP session opened.
+    pub fn udp_session_opened(&self) {
+        self.active_udp_sessions.fetch_add(1, Ordering::Relaxed);
+        self.total_udp_sessions.fetch_add(1, Ordering::Relaxed);
+    }
+
+    /// Record a UDP session closed.
+    pub fn udp_session_closed(&self) {
+        self.active_udp_sessions.fetch_sub(1, Ordering::Relaxed);
+    }
+
+    /// Record a UDP datagram (inbound or outbound).
+    pub fn record_datagram_in(&self) {
+        self.total_datagrams_in.fetch_add(1, Ordering::Relaxed);
+    }
+
+    /// Record an outbound UDP datagram.
+    pub fn record_datagram_out(&self) {
+        self.total_datagrams_out.fetch_add(1, Ordering::Relaxed);
+    }
+
     // ── Per-backend recording methods ──
 
     /// Record a successful backend connection with its connect duration.
@@ -769,6 +807,10 @@ impl MetricsCollector {
             total_http_requests: self.total_http_requests.load(Ordering::Relaxed),
             http_requests_per_sec: http_rps,
             http_requests_per_sec_recent: http_rps_recent,
+            active_udp_sessions: self.active_udp_sessions.load(Ordering::Relaxed),
+            total_udp_sessions: self.total_udp_sessions.load(Ordering::Relaxed),
+            total_datagrams_in: self.total_datagrams_in.load(Ordering::Relaxed),
+            total_datagrams_out: self.total_datagrams_out.load(Ordering::Relaxed),
         }
     }
 }