Precompile native modules off request path

src/wasm/worker.cpp

@@ -1049,6 +1049,36 @@ public:
 		return(unit);
 	}
 
+	static bool serialized_module_needs_refresh(const String& wasm_path)
+	{
+		struct stat wasm_stat;
+		struct stat cached_stat;
+		String cached_path = cached_wasm_path(wasm_path);
+		if(stat(wasm_path.c_str(), &wasm_stat) != 0)
+			return(false);
+		if(stat(cached_path.c_str(), &cached_stat) != 0)
+			return(true);
+		return(cached_stat.st_mtim.tv_sec < wasm_stat.st_mtim.tv_sec ||
+			(cached_stat.st_mtim.tv_sec == wasm_stat.st_mtim.tv_sec && cached_stat.st_mtim.tv_nsec <= wasm_stat.st_mtim.tv_nsec));
+	}
+
+	static String serialize_module_artifact(const String& wasm_path)
+	{
+		if(!serialized_module_needs_refresh(wasm_path))
+			return("");
+		std::vector<u8> bytes;
+		if(!wasm_read_file(wasm_path, bytes))
+			return("cannot read " + wasm_path);
+		wasmtime::Engine engine = make_engine();
+		String error;
+		auto module = compile_and_cache_module(engine, cached_wasm_path(wasm_path), bytes, error);
+		if(!module)
+			return(error);
+		if(serialized_module_needs_refresh(wasm_path))
+			return("cannot publish serialized module for " + wasm_path);
+		return("");
+	}
+
 private:
 	static String cached_wasm_path(const String& wasm_path)
 	{