fix: avoid resending terminal cells for metadata updates (#4137)

1 files changed, 86 insertions, 0 deletions

diff --git a/src/server/render_scale_benchmark.rs b/src/server/render_scale_benchmark.rs
index 7503f06d..82f7ba91 100644
--- a/src/server/render_scale_benchmark.rs
+++ b/src/server/render_scale_benchmark.rs
@@ -312,6 +312,91 @@ fn print_token_rule_profiles() {
     }
 }
 
+fn print_surface_reuse_profiles() {
+    println!("surface encode + decode at {COLS}x{ROWS}");
+    println!("  layout       panes  cells_changed  reuse  median_us  bytes_per_update");
+    for (label, build) in [
+        ("background", workspaces as fn(usize) -> Vec<Workspace>),
+        ("active", active_panes),
+    ] {
+        for count in [1, 15] {
+            let mut pipeline = RenderPipeline::new(build(count));
+            pipeline.render_once();
+            let rendered = super::client_shell::render_pane_surface(
+                &mut pipeline.app,
+                Some(crate::ui::TabSurfaceTarget {
+                    workspace_index: 0,
+                    tab_index: 0,
+                }),
+                Rect::new(0, 0, COLS, ROWS),
+                true,
+                false,
+                HostCellSize::default(),
+                &pipeline.graphics_delivery,
+                1,
+            );
+            let surface = PaneSurfaceFrame {
+                boot_id: "bench-boot".into(),
+                projection_revision: 1,
+                surface_revision: 0,
+                frame: rendered.frame,
+                panes: rendered.panes,
+                splits: rendered.splits,
+                popup: rendered.popup,
+                graphics: rendered.graphics,
+            };
+            for cells_changed in [false, true] {
+                for enabled in [false, true] {
+                    let mut state = super::render_stream::ClientRenderState::new(
+                        crate::protocol::RenderEncoding::SemanticFrame,
+                    );
+                    state.enable_surface_reuse(enabled);
+                    let mut decoder = crate::protocol::surface_reuse::Decoder::default();
+                    let initial = state.prepare_pane_surface(surface.clone()).unwrap();
+                    if enabled {
+                        decoder.decode(initial.message().clone()).unwrap();
+                    }
+                    state.commit_sent_frame(initial);
+                    let mut samples = Vec::new();
+                    let mut bytes_per_update = 0;
+                    for index in 0..WARMUP_COUNT + SAMPLE_COUNT {
+                        let mut candidate = surface.clone();
+                        candidate.projection_revision = index as u64 + 2;
+                        if cells_changed {
+                            candidate.frame.cells[0].symbol =
+                                if index % 2 == 0 { "a" } else { "b" }.into();
+                        }
+                        let started = Instant::now();
+                        let prepared = state.prepare_pane_surface(candidate).unwrap();
+                        let mut bytes = Vec::new();
+                        crate::protocol::write_message(&mut bytes, prepared.message()).unwrap();
+                        bytes_per_update = bytes.len();
+                        let decoded = crate::protocol::read_message(
+                            &mut bytes.as_slice(),
+                            crate::protocol::MAX_FRAME_SIZE,
+                        )
+                        .unwrap();
+                        black_box(if enabled {
+                            decoder.decode(decoded).unwrap()
+                        } else {
+                            decoded
+                        });
+                        state.commit_sent_frame(prepared);
+                        if index >= WARMUP_COUNT {
+                            samples.push(started.elapsed());
+                        }
+                    }
+                    let stats = summarize(samples);
+                    println!(
+                    "  {label:<10}  {count:>5}  {cells_changed:>13}  {enabled:>5}  {:>9}  {bytes_per_update:>16}",
+                    stats.median_us
+                );
+                }
+            }
+        }
+    }
+}
+
 #[tokio::test(flavor = "current_thread")]
 #[ignore = "manual client-rendered pipeline scaling profile"]
 async fn render_scale_profile() {
@@ -320,4 +405,5 @@ async fn render_scale_profile() {
     print_profiles("active panes (one workspace)", active_panes);
     print_snapshot_encoding_profiles("active panes", active_panes);
     print_token_rule_profiles();
+    print_surface_reuse_profiles();
 }