From 349ed806001ace5841534642200258b50e98a91d Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Tue, 20 Jan 2026 18:40:18 +0000
Subject: [PATCH] =?UTF-8?q?=E2=9A=A1=20Bolt:=20Replace=20blocking=20XSync?=
 =?UTF-8?q?=20with=20XFlush=20in=20hot=20paths?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .jules/bolt.md | 3 +++
 client.c       | 2 +-
 drw.c          | 2 +-
 3 files changed, 5 insertions(+), 2 deletions(-)
 create mode 100644 .jules/bolt.md

diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 00000000..b8f2743b
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2026-01-20 - XSync vs XFlush in Event-Driven Drawing
+**Learning:** `XSync` is a blocking round-trip to the X server, while `XFlush` is asynchronous. In `instantwm`, `XSync` was used in `drw_map` (called on every bar redraw) and `resizeclient` (called on every window resize), causing significant performance degradation due to unnecessary waiting for server confirmation.
+**Action:** Replace `XSync` with `XFlush` in high-frequency drawing/window management paths when immediate confirmation is not strictly required for logic correctness.
diff --git a/client.c b/client.c
index 13f1e27f..c03e6b4b 100644
--- a/client.c
+++ b/client.c
@@ -279,7 +279,7 @@ void resizeclient(Client *c, int x, int y, int w, int h) {
     XConfigureWindow(dpy, c->win,
                      CWX | CWY | CWWidth | CWHeight | CWBorderWidth, &wc);
     configure(c);
-    XSync(dpy, False);
+    XFlush(dpy);
 }
 
 void updatetitle(Client *c) {
diff --git a/drw.c b/drw.c
index 7e99a386..e3f9501b 100644
--- a/drw.c
+++ b/drw.c
@@ -494,7 +494,7 @@ void drw_map(Drw *drw, Window win, int x, int y, unsigned int w,
     }
 
     XCopyArea(drw->dpy, drw->drawable, win, drw->gc, x, y, w, h, x, y);
-    XSync(drw->dpy, False);
+    XFlush(drw->dpy);
 }
 
 unsigned int drw_fontset_getwidth(Drw *drw, const char *text) {