From 00704fbdfe71c5a50b6b179ee463798b63360be6 Mon Sep 17 00:00:00 2001
From: Brent Echols <brentiechols@gmail.com>
Date: Sat, 15 Aug 2026 14:17:10 -0700
Subject: [PATCH] perf: defer send buffer locking while receiving

---
 src/proto/streams/streams.rs | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/src/proto/streams/streams.rs b/src/proto/streams/streams.rs
index ba326d0d..46955159 100644
--- a/src/proto/streams/streams.rs
+++ b/src/proto/streams/streams.rs
@@ -536,8 +536,6 @@ impl Inner {
         }
 
         let actions = &mut self.actions;
-        let mut send_buffer = send_buffer.inner.lock().unwrap();
-        let send_buffer = &mut *send_buffer;
 
         self.counts.transition(stream, |counts, stream| {
             tracing::trace!(
@@ -551,8 +549,9 @@ impl Inner {
                     Ok(()) => Ok(()),
                     Err(RecvHeaderBlockError::Oversize(resp)) => {
                         if let Some(resp) = resp {
+                            let mut send_buffer = send_buffer.inner.lock().unwrap();
                             let sent = actions.send.send_headers(
-                                resp, send_buffer, stream, counts, &mut actions.task);
+                                resp, &mut send_buffer, stream, counts, &mut actions.task);
                             debug_assert!(sent.is_ok(), "oversize response should not fail");
 
                             actions.send.schedule_implicit_reset(
@@ -581,7 +580,7 @@ impl Inner {
                 actions.recv.recv_trailers(frame, stream)
             };
 
-            actions.reset_on_recv_stream_err(send_buffer, stream, counts, res)
+            actions.reset_on_recv_stream_err_deferred(send_buffer, stream, counts, res)
         })
     }
 
@@ -633,8 +632,6 @@ impl Inner {
         };
 
         let actions = &mut self.actions;
-        let mut send_buffer = send_buffer.inner.lock().unwrap();
-        let send_buffer = &mut *send_buffer;
 
         self.counts.transition(stream, |counts, stream| {
             let sz = frame.flow_controlled_len();
@@ -648,7 +645,7 @@ impl Inner {
                     .recv
                     .release_connection_capacity(sz as WindowSize, &mut None);
             }
-            actions.reset_on_recv_stream_err(send_buffer, stream, counts, res)
+            actions.reset_on_recv_stream_err_deferred(send_buffer, stream, counts, res)
         })
     }
 
@@ -1739,6 +1736,21 @@ impl Actions {
         })
     }
 
+    fn reset_on_recv_stream_err_deferred<B>(
+        &mut self,
+        send_buffer: &SendBuffer<B>,
+        stream: &mut store::Ptr,
+        counts: &mut Counts,
+        res: Result<(), Error>,
+    ) -> Result<(), Error> {
+        if matches!(res, Err(Error::Reset(..))) {
+            let mut send_buffer = send_buffer.inner.lock().unwrap();
+            self.reset_on_recv_stream_err(&mut send_buffer, stream, counts, res)
+        } else {
+            res
+        }
+    }
+
     fn reset_on_recv_stream_err<B>(
         &mut self,
         buffer: &mut Buffer<Frame<B>>,