From 8b0c37bc8385b8fa4fd37cd7383fa75e1d6c3496 Mon Sep 17 00:00:00 2001
From: Nils Andreas Svee <me@lochnair.net>
Date: Sun, 5 Jul 2026 12:44:30 +0700
Subject: [PATCH] refactor: simplify control flow and error handling in metrics
 and netlink

---
 src/metrics.rs        | 20 ++++++++----------
 src/netlink.rs        | 24 ++++++++++------------
 src/ratecontroller.rs | 48 ++++++++++++++++++++++---------------------
 3 files changed, 45 insertions(+), 47 deletions(-)

diff --git a/src/metrics.rs b/src/metrics.rs
index 1fcf806..35d8762 100644
--- a/src/metrics.rs
+++ b/src/metrics.rs
@@ -78,12 +78,13 @@ impl Transport {
 
                 let full_data = format!("{}\n", data);
                 // take the stream out, write, put it back or set None on failure
-                if let Some(s) = stream {
-                    if let Err(e) = std::io::Write::write_all(s, full_data.as_bytes()) {
-                        warn!("TCP send failed: {}", e);
-                        *stream = None;
-                        *reconnect_backoff = (*reconnect_backoff * 2).min(MAX_RECONNECT_BACKOFF);
-                    }
+                let write_error = stream
+                    .as_mut()
+                    .and_then(|s| std::io::Write::write_all(s, full_data.as_bytes()).err());
+                if let Some(e) = write_error {
+                    warn!("TCP send failed: {}", e);
+                    *stream = None;
+                    *reconnect_backoff = (*reconnect_backoff * 2).min(MAX_RECONNECT_BACKOFF);
                 }
             }
         }
@@ -209,11 +210,8 @@ impl Metrics {
             }
 
             // greedily drain without blocking
-            loop {
-                match self.metrics_rx.try_recv() {
-                    Ok(metric) => batch.push(metric),
-                    Err(_) => break,
-                }
+            while let Ok(metric) = self.metrics_rx.try_recv() {
+                batch.push(metric);
                 if batch.len() >= batch_size {
                     break;
                 }
diff --git a/src/netlink.rs b/src/netlink.rs
index d100553..84e3df8 100644
--- a/src/netlink.rs
+++ b/src/netlink.rs
@@ -85,19 +85,17 @@ impl Netlink {
         while let Some(reply) = iter.recv() {
             let (header, attrs) = reply?;
 
-            if header.ifindex == ifindex {
-                if let Ok(kind) = attrs.get_kind() {
-                    if kind
-                        .to_str()
-                        .map_err(|_| NetlinkError::NlQdiscError("Invalid UTF-8".to_string()))?
-                        == "cake"
-                    {
-                        return Ok(Qdisc {
-                            ifindex,
-                            parent: header.parent,
-                        });
-                    }
-                }
+            if header.ifindex == ifindex
+                && let Ok(kind) = attrs.get_kind()
+                && kind
+                    .to_str()
+                    .map_err(|_| NetlinkError::NlQdiscError("Invalid UTF-8".to_string()))?
+                    == "cake"
+            {
+                return Ok(Qdisc {
+                    ifindex,
+                    parent: header.parent,
+                });
             }
         }
 
diff --git a/src/ratecontroller.rs b/src/ratecontroller.rs
index fbd5385..824afba 100644
--- a/src/ratecontroller.rs
+++ b/src/ratecontroller.rs
@@ -446,8 +446,8 @@ impl Ratecontroller {
                     delta_delay_up: self.state_ul.delta_stat,
                 });
 
-                if let Some(ref mut fd) = stats_fd {
-                    if let Err(e) = fd.write_all(
+                let stats_write_error = stats_fd.as_mut().and_then(|fd| {
+                    fd.write_all(
                         format!(
                             "{},{},{},{},{},{},{},{}\n",
                             stats_time.secs(),
@@ -460,34 +460,36 @@ impl Ratecontroller {
                             self.state_ul.current_rate as u64
                         )
                         .as_bytes(),
-                    ) {
-                        warn!("Failed to write statistics: {}", e);
-                    }
+                    )
+                    .err()
+                });
+                if let Some(e) = stats_write_error {
+                    warn!("Failed to write statistics: {}", e);
                 }
 
                 lastchg_t = now_t;
             }
 
-            if let Some(ref mut fd) = speed_hist_fd {
-                if now_t.duration_since(lastdump_t).as_secs_f64() > 300.0 {
-                    for i in 0..self.config.speed_hist_size as usize {
-                        let hist_time = Time::new(ClockId::Realtime);
-                        if let Err(e) = fd.write_all(
-                            format!(
-                                "{},{},{},{}\n",
-                                hist_time.as_secs_f64(),
-                                i,
-                                self.state_ul.safe_rates[i],
-                                self.state_dl.safe_rates[i]
-                            )
-                            .as_bytes(),
-                        ) {
-                            warn!("Failed to write speed history file: {}", e);
-                        }
+            if let Some(ref mut fd) = speed_hist_fd
+                && now_t.duration_since(lastdump_t).as_secs_f64() > 300.0
+            {
+                for i in 0..self.config.speed_hist_size as usize {
+                    let hist_time = Time::new(ClockId::Realtime);
+                    if let Err(e) = fd.write_all(
+                        format!(
+                            "{},{},{},{}\n",
+                            hist_time.as_secs_f64(),
+                            i,
+                            self.state_ul.safe_rates[i],
+                            self.state_dl.safe_rates[i]
+                        )
+                        .as_bytes(),
+                    ) {
+                        warn!("Failed to write speed history file: {}", e);
                     }
-
-                    lastdump_t = now_t;
                 }
+
+                lastdump_t = now_t;
             }
         }
     }