Merge branch 'flow' into fix/apply-tg-connect-timeout-upstream

src/config/defaults.rs

@@ -209,6 +209,10 @@ pub(crate) fn default_server_max_connections() -> u32 {
     10_000
 }
 
+pub(crate) fn default_listen_backlog() -> u32 {
+    1024
+}
+
 pub(crate) fn default_accept_permit_timeout_ms() -> u64 {
     DEFAULT_ACCEPT_PERMIT_TIMEOUT_MS
 }

src/config/hot_reload.rs

@@ -570,6 +570,7 @@ fn warn_non_hot_changes(old: &ProxyConfig, new: &ProxyConfig, non_hot_changed: b
     }
     if old.server.proxy_protocol != new.server.proxy_protocol
         || !listeners_equal(&old.server.listeners, &new.server.listeners)
+        || old.server.listen_backlog != new.server.listen_backlog
         || old.server.listen_addr_ipv4 != new.server.listen_addr_ipv4
         || old.server.listen_addr_ipv6 != new.server.listen_addr_ipv6
         || old.server.listen_tcp != new.server.listen_tcp

src/config/types.rs

@@ -1277,6 +1277,11 @@ pub struct ServerConfig {
     #[serde(default)]
     pub listeners: Vec<ListenerConfig>,
 
+    /// TCP `listen(2)` backlog for client-facing sockets (also used for the metrics HTTP listener).
+    /// The effective queue is capped by the kernel (for example `somaxconn` on Linux).
+    #[serde(default = "default_listen_backlog")]
+    pub listen_backlog: u32,
+
     /// Maximum number of concurrent client connections.
     /// 0 means unlimited.
     #[serde(default = "default_server_max_connections")]
@@ -1305,6 +1310,7 @@ impl Default for ServerConfig {
             metrics_whitelist: default_metrics_whitelist(),
             api: ApiConfig::default(),
             listeners: Vec::new(),
+            listen_backlog: default_listen_backlog(),
             max_connections: default_server_max_connections(),
             accept_permit_timeout_ms: default_accept_permit_timeout_ms(),
         }