chore(monitor): add debug log for client dns resolve (#14229)

src/common/src/monitor/connection.rs

@@ -16,24 +16,27 @@ use std::any::type_name;
 use std::cmp::Ordering;
 use std::future::Future;
 use std::io::{Error, IoSlice};
+use std::net::SocketAddr;
 use std::pin::Pin;
 use std::sync::LazyLock;
 use std::task::{Context, Poll};
 use std::time::Duration;
 
 use futures::FutureExt;
 use http::Uri;
+use hyper::client::connect::dns::{GaiAddrs, GaiFuture, GaiResolver, Name};
 use hyper::client::connect::Connection;
 use hyper::client::HttpConnector;
 use hyper::service::Service;
+use itertools::Itertools;
 use pin_project_lite::pin_project;
 use prometheus::{
     register_int_counter_vec_with_registry, register_int_gauge_vec_with_registry, IntCounter,
     IntCounterVec, IntGauge, IntGaugeVec, Registry,
 };
 use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
 use tonic::transport::{Channel, Endpoint};
-use tracing::{info, warn};
+use tracing::{debug, info, warn};
 
 use crate::metrics::LabelGuardedIntCounterVec;
 use crate::monitor::GLOBAL_METRICS_REGISTRY;
@@ -388,6 +391,92 @@ pub fn monitor_connector<C>(
     MonitoredConnection::new(connector, MonitorNewConnectionImpl { connection_type })
 }
 
+pub struct MonitoredGaiAddrs {
+    inner: Vec<SocketAddr>,
+    pos: usize,
+}
+
+impl From<GaiAddrs> for MonitoredGaiAddrs {
+    fn from(value: GaiAddrs) -> Self {
+        Self {
+            inner: value.collect_vec(),
+            pos: 0,
+        }
+    }
+}
+
+impl Iterator for MonitoredGaiAddrs {
+    type Item = SocketAddr;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let res = self.inner.get(self.pos).cloned();
+        self.pos += 1;
+        res
+    }
+}
+
+pub struct MonitoredGaiFuture {
+    name: Name,
+    inner: GaiFuture,
+}
+
+impl std::fmt::Debug for MonitoredGaiFuture {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.pad("MonitoredGaiFuture")
+    }
+}
+
+impl Future for MonitoredGaiFuture {
+    type Output = Result<MonitoredGaiAddrs, Error>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        Pin::new(&mut self.inner).poll(cx).map(|res| match res {
+            Ok(addrs) => {
+                let addrs: MonitoredGaiAddrs = addrs.into();
+                debug!("resolve {} => {:?}", self.name, addrs.inner);
+                Ok(addrs)
+            }
+            Err(err) => Err(err),
+        })
+    }
+}
+
+#[derive(Clone)]
+pub struct MonitoredGaiResolver {
+    inner: GaiResolver,
+}
+
+impl std::fmt::Debug for MonitoredGaiResolver {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.pad("MonitoredGaiResolver")
+    }
+}
+
+impl Default for MonitoredGaiResolver {
+    fn default() -> Self {
+        Self {
+            inner: GaiResolver::new(),
+        }
+    }
+}
+
+impl Service<Name> for MonitoredGaiResolver {
+    type Error = Error;
+    type Future = MonitoredGaiFuture;
+    type Response = MonitoredGaiAddrs;
+
+    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.inner.poll_ready(cx)
+    }
+
+    fn call(&mut self, req: Name) -> Self::Future {
+        MonitoredGaiFuture {
+            name: req.clone(),
+            inner: self.inner.call(req),
+        }
+    }
+}
+
 #[easy_ext::ext(EndpointExt)]
 impl Endpoint {
     pub async fn monitored_connect(
@@ -397,7 +486,9 @@ impl Endpoint {
     ) -> Result<Channel, tonic::transport::Error> {
         #[cfg(not(madsim))]
         {
-            let mut http = HttpConnector::new();
+            let resolver = MonitoredGaiResolver::default();
+            let mut http = HttpConnector::new_with_resolver(resolver);
+
             http.enforce_http(false);
             http.set_nodelay(config.tcp_nodelay);
             http.set_keepalive(config.keepalive_duration);