From 33ff3488f89b3e89ed31780ff7ab72128abe5312 Mon Sep 17 00:00:00 2001
From: brian cully <bjc@spork.org>
Date: Mon, 29 Dec 2025 12:19:06 -0500
Subject: wasm: add benchmarking

---
 Cargo.toml      |  4 +++-
 site/index.html |  2 +-
 src/lib.rs      | 43 +++++++++++++++++++++++++++++++++++++++----
 3 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index bd6395a..c0df418 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,5 +18,7 @@ features = ["js"]
 version = "2.3"
 
 [dependencies.web-sys]
-features = ["Document", "DocumentTimeline", "Element", "Event", "HtmlElement", "HtmlCanvasElement", "CanvasRenderingContext2d", "Node", "Window"]
+features = ["CanvasRenderingContext2d", "Document", "DocumentTimeline",
+            "Element", "Event", "HtmlCanvasElement", "HtmlElement", "HtmlInputElement",
+            "Node", "Performance", "Window"]
 version = "0.3"
diff --git a/site/index.html b/site/index.html
index dd747c1..e978b31 100644
--- a/site/index.html
+++ b/site/index.html
@@ -22,7 +22,7 @@
 
     <section class='bench'>
       <h2>bench</h2>
-      <input name='iters' value='1000'>
+      <input name='iters' value='100000'>
       <button>bench</button>
     </section>
 
diff --git a/src/lib.rs b/src/lib.rs
index 7dd08e9..60fdc0f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,4 @@
-use std::rc::Rc;
+use std::{cell::RefCell, rc::Rc};
 use std::sync::Mutex;
 
 use log::{Level, debug, info};
@@ -26,17 +26,27 @@ fn document() -> web_sys::Document {
 
 fn canvas() -> JSResult<web_sys::HtmlCanvasElement> {
     let x = document().query_selector("section.watch canvas")?.ok_or("no canvas")?;
-    Ok(x.dyn_into::<web_sys::HtmlCanvasElement>()?)
+    Ok(x.dyn_into()?)
 }
 
 fn fps() -> JSResult<web_sys::HtmlElement> {
     let x = document().query_selector("section.watch .fps")?.ok_or("no fps counter")?;
-    Ok(x.dyn_into::<web_sys::HtmlElement>()?)
+    Ok(x.dyn_into()?)
 }
 
 fn go() -> JSResult<web_sys::HtmlElement> {
     let x = document().query_selector("section.watch button")?.ok_or("no go button")?;
-    Ok(x.dyn_into::<web_sys::HtmlElement>()?)
+    Ok(x.dyn_into()?)
+}
+
+fn iters() -> JSResult<web_sys::HtmlInputElement> {
+    let x = document().query_selector("section.bench input")?.ok_or("no go button")?;
+    Ok(x.dyn_into()?)
+}
+
+fn bench() -> JSResult<web_sys::HtmlElement> {
+    let x = document().query_selector("section.bench button")?.ok_or("no go button")?;
+    Ok(x.dyn_into()?)
 }
 
 #[wasm_bindgen(start)]
@@ -51,7 +61,11 @@ pub fn init() -> JSResult<()> {
     let mut s = State::new(canvas()?, fps()?)?;
     s.render_frame(0.0)?;
 
+    let shared_s = Rc::new(RefCell::new(s));
+    let s1 = shared_s.clone();
+
     let render_loop = RenderLoop::new(move |t| {
+        let mut s = shared_s.borrow_mut();
         s.update()?;
         s.render_frame(t)?;
         Ok(!*paused.lock().unwrap())
@@ -75,5 +89,26 @@ pub fn init() -> JSResult<()> {
     // handler.
     go_handler.forget();
 
+    let bench_handler: HandlerClosure = Closure::new(move |e| {
+        debug!("bench clicked {:?}", e);
+        let iters = iters()?.value().parse::<u32>().map_err(|_| "iters isn't int")?;
+
+        let mut s = s1.borrow_mut();
+        let perf = window().performance().unwrap();
+        let start = perf.now();
+        for _ in 0..iters {
+            s.update()?;
+        }
+        let end = perf.now();
+        let delta = end - start;
+        let iters_per_ms = Into::<f64>::into(iters) / delta;
+
+        info!("bench done. {iters} iters in {delta} ms ({iters_per_ms} iters per ms)");
+        Ok(())
+    });
+    bench()?.set_onclick(Some(bench_handler.as_ref().unchecked_ref()));
+    // ibid.
+    bench_handler.forget();
+
     Ok(())
 }
-- 
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