Merge pull request #11757 from kacpherek/perf/render-api-tracking

an edit in game/ no longer rebuilds the renderer: dev rebuild 22.7 s -> 12.0 s

Cargo.toml

@@ -82,6 +82,21 @@ libmimalloc-sys = { path = "third_party/libmimalloc-sys" }
 [profile.dev]
 debug = "line-tables-only"
 
+# The native mod API is generated by a build script that parses every file of game/ with syn on
+# each gameplay edit; unoptimized that took ~6 s of every rebuild, optimized ~1.5 s.
+[profile.dev.package.horizon-mod-api-gen]
+opt-level = 3
+[profile.dev.package.syn]
+opt-level = 3
+[profile.dev.package.proc-macro2]
+opt-level = 3
+[profile.release.package.horizon-mod-api-gen]
+opt-level = 3
+[profile.release.package.syn]
+opt-level = 3
+[profile.release.package.proc-macro2]
+opt-level = 3
+
 [profile.release]
 lto = "thin"
 codegen-units = 1

crates/horizon-mod-api-gen/src/build.rs

@@ -6,7 +6,7 @@ use std::{collections::HashSet, fs, path::Path};
 /// Generate only this crate's files, tracking every source read by the generator.
 /// `root` is supplied at run time by the consuming crate's build script.
 pub fn generate(root: &Path, out_dir: &Path, target: Target) -> Result<(), String> {
-    track(root)?;
+    track(root, target)?;
     let generated = sources(root, super::FillMode::Require)?;
     let outputs = match target {
         Target::Render => vec![("native_render_generated.rs", generated.render)],
@@ -35,7 +35,7 @@ pub fn generate(root: &Path, out_dir: &Path, target: Target) -> Result<(), Strin
     Ok(())
 }
 
-pub(super) fn track(root: &Path) -> Result<(), String> {
+pub(super) fn track(root: &Path, target: Target) -> Result<(), String> {
     fn directory(path: &Path, extension: &str, recursive: bool) -> Result<(), String> {
         // Track the directory as well: adding a helper source or fragment changes the inputs.
         println!("cargo:rerun-if-changed={}", path.display());
@@ -53,7 +53,18 @@ pub(super) fn track(root: &Path) -> Result<(), String> {
         println!("cargo:rerun-if-changed={}", root.join(path).display());
     }
     directory(&root.join("tools/native-hook-fragments"), "json", false)?;
-    directory(&root.join("crates/horizon-client/src/game"), "rs", true)?;
+    match target {
+        // The host API is made from every `impl Game` method under game/.
+        Target::Client => directory(&root.join("crates/horizon-client/src/game"), "rs", true)?,
+        // The render hooks read only native_hooks.rs (and their own functions, tracked below).
+        // Tracking all of game/ here rebuilt the renderer, and horizon-client-lib above it, on
+        // every gameplay edit.
+        Target::Render => println!(
+            "cargo:rerun-if-changed={}",
+            root.join("crates/horizon-client/src/game/native_hooks.rs")
+                .display()
+        ),
+    }
     let catalog = serde_json::from_str(
         &fs::read_to_string(root.join("native-hooks.json")).map_err(|e| e.to_string())?,
     )

crates/horizon-mod-api-gen/src/lib.rs

@@ -1159,7 +1159,7 @@ mod injection_tests;
 /// Generate a dispatch fixture without preventing xtask from filling placeholders.
 #[doc(hidden)]
 pub fn generate_test_hooks(root: &Path, out_dir: &Path) -> Result<(), String> {
-    build::track(root)?;
+    build::track(root, Target::Client)?;
     let code = sources(root, FillMode::Ignore)?.hooks;
     fs::write(out_dir.join("mod_api_generated.rs"), code).map_err(|e| e.to_string())
 }