fix(macos): drain autoreleased CoreWLAN objects in get_wifi_transmit_rate

Cargo.toml

@@ -42,6 +42,7 @@ objc2-system-configuration = { version = "0.3", features = ["SCNetworkConfigurat
 plist = "1.8"
 
 [target.'cfg(target_os = "macos")'.dependencies]
+objc2 = { version = "0.6" }
 objc2-core-wlan = { version = "0.3" }
 objc2-foundation = { version = "0.3" }
 

src/os/macos/wifi.rs

@@ -1,14 +1,26 @@
+use objc2::rc::autoreleasepool;
 use objc2_core_wlan::CWWiFiClient;
 use objc2_foundation::NSString;
 
 /// Returns the macOS Wi-Fi transmit rate in bps for the given interface name.
+///
+/// The CoreWLAN calls below produce autoreleased Obj-C/XPC objects
+/// (`CWFRequestParameters`, `CWFInterface`, the `CWFXPCRequestProtocolCoreWLAN`
+/// proxy). This is called from long-lived threads with no draining autorelease
+/// pool (e.g. `netwatch`'s interface monitor re-enumerates on every network
+/// event), so without an explicit pool those objects are added to a pool that
+/// never drains and accumulate without bound — a steady multi-MB/hour macOS
+/// leak. A scoped pool per call frees them immediately.
 pub(crate) fn get_wifi_transmit_rate(iface_name: &str) -> Option<u64> {
-    let client = unsafe { CWWiFiClient::sharedWiFiClient() };
-    let name = NSString::from_str(iface_name);
+    autoreleasepool(|_pool| {
+        let client = unsafe { CWWiFiClient::sharedWiFiClient() };
+        let name = NSString::from_str(iface_name);
 
-    let wifi_iface = unsafe { client.interfaceWithName(Some(&name)) };
-    wifi_iface.map(|i| {
-        let transmit_rate = unsafe { i.transmitRate() };
-        return (transmit_rate * 1e6) as u64;
+        let wifi_iface = unsafe { client.interfaceWithName(Some(&name)) };
+        wifi_iface.map(|i| {
+            let transmit_rate = unsafe { i.transmitRate() };
+            (transmit_rate * 1e6) as u64
+        })
     })
 }
+