From cb9cbacdd3bcfa98c2b9527be97a25a839d7a951 Mon Sep 17 00:00:00 2001
From: DualFroz <me@dualfroz.com>
Date: Fri, 11 Sep 2026 23:33:21 +0200
Subject: [PATCH] fix(server): Do not panic when a channel read fails

A read timeout or an abrupt client hang-up unwound the channel thread,
which flooded the logs with "closing channel" panics and skipped the
connected clients counter decrement, leaking a client slot each time.

Fixes #256
---
 server/src/channel/handle.rs         |  6 ++--
 server/tests/channel_read_timeout.rs | 50 ++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 server/tests/channel_read_timeout.rs

diff --git a/server/src/channel/handle.rs b/server/src/channel/handle.rs
index 74a5f90..05e136c 100644
--- a/server/src/channel/handle.rs
+++ b/server/src/channel/handle.rs
@@ -216,9 +216,11 @@ impl ChannelHandle {
                     }
                 }
                 Err(err) => {
-                    tracing::error!("closing channel thread with traceback: {}", err);
+                    // NOTE: Panicking here would unwind past the connected clients
+                    //   counter decrement in `client()`, leaking a client slot.
+                    tracing::debug!("closing channel thread: {}", err);
 
-                    panic!("closing channel");
+                    break 'handler;
                 }
             }
         }
diff --git a/server/tests/channel_read_timeout.rs b/server/tests/channel_read_timeout.rs
new file mode 100644
index 0000000..8a28460
--- /dev/null
+++ b/server/tests/channel_read_timeout.rs
@@ -0,0 +1,50 @@
+// Sonic
+//
+// Fast, lightweight and schema-less search backend
+// Copyright: 2026, DualFroz <me@dualfroz.com>
+// License: Mozilla Public License v2.0 (MPL v2.0)
+
+mod common;
+
+use std::io::{BufRead, BufReader, Write};
+use std::net::TcpStream;
+use std::time::Duration;
+
+use crate::common::prelude::*;
+
+const TCP_TIMEOUT: u64 = 1;
+
+#[test]
+fn read_timeout_releases_client_slot() {
+    let ctx =
+        start_empty(|command| command.env("SONIC_CHANNEL__TCP_TIMEOUT", TCP_TIMEOUT.to_string()));
+
+    {
+        let mut stream = TcpStream::connect(ctx.addr).unwrap();
+        let mut reader = BufReader::new(stream.try_clone().unwrap());
+        let mut line = String::new();
+
+        reader.read_line(&mut line).unwrap();
+
+        stream
+            .write_all(format!("START search {SONIC_PASSWORD}\n").as_bytes())
+            .unwrap();
+
+        line.clear();
+        reader.read_line(&mut line).unwrap();
+        assert!(line.starts_with("STARTED"), "unexpected greeting: {line:?}");
+
+        // Stay idle until the server hits its read timeout, then hang up.
+        std::thread::sleep(Duration::from_secs(TCP_TIMEOUT + 1));
+    }
+
+    std::thread::sleep(Duration::from_millis(200));
+
+    let multiplexer = SonicMultiplexer::new().unwrap();
+    let control =
+        SonicChannelControlBlocking::connect(ctx.addr, SONIC_PASSWORD, &multiplexer).unwrap();
+
+    let stats = control.info().unwrap();
+
+    assert_eq!(stats.clients_connected, 1);
+}