v0.34.0_8

src/logging/format.rs

@@ -138,11 +138,21 @@ impl Logs {
     pub fn push(&self, entry: LogEntry) {
         let has_viewers = self.live.receiver_count() != 0;
         let has_sink = self.settings.load().enabled();
-        // The usual history-only configuration needs no deep copy at all.
-        // When external consumers are present, clone exactly for history and
-        // keep the original entry available for streaming/sink delivery.
+        // Reserve the bounded sink slot BEFORE cloning a log entry. Under
+        // saturation, the failed enqueue must not copy 30+ owned fields.
+        let sink_permit = if has_sink {
+            match self.sink.try_reserve() {
+                Ok(permit) => Some(permit),
+                Err(_) => {
+                    self.sink_dropped.fetch_add(1, Ordering::Relaxed);
+                    None
+                }
+            }
+        } else {
+            None
+        };
         let mut external = Some(entry);
-        let history_entry = if has_viewers || has_sink {
+        let history_entry = if has_viewers || sink_permit.is_some() {
             external.as_ref().expect("entry").clone()
         } else {
             external.take().expect("entry")
@@ -165,10 +175,8 @@ impl Logs {
             if has_viewers {
                 let _ = self.live.send(entry.clone());
             }
-            // Snapshot the sink choice once. This preserves sink drop
-            // accounting and avoids a second ArcSwap load per request.
-            if has_sink && self.sink.try_send(entry).is_err() {
-                self.sink_dropped.fetch_add(1, Ordering::Relaxed);
+            if let Some(permit) = sink_permit {
+                permit.send(entry);
             }
         }
     }