perf counter macros

rust-engine-proc/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "rust-engine-proc"
+version = "0.1.0"
+edition = "2018"
+
+[lib]
+proc-macro = true
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+syn = { version = "1.0", features = ["full"] }
+quote = "1.0"

rust-engine-proc/src/lib.rs

@@ -0,0 +1,28 @@
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{AttributeArgs, ItemFn, Lit, Meta, parse_macro_input, parse_quote};
+
+#[proc_macro_attribute]
+pub fn perf(attr: TokenStream, item: TokenStream) -> TokenStream {
+    let attrs = parse_macro_input!(attr as AttributeArgs);
+    let name = match &attrs[0] {
+        syn::NestedMeta::Lit(Lit::Str(l)) => l.value(),
+        _ => panic!("Invalid attribute"),
+    };
+    let counter_type = match &attrs[1] {
+        syn::NestedMeta::Meta(Meta::Path(p)) => p,
+        _ => panic!("Invalid attribute"),
+    };
+    let mut function = parse_macro_input!(item as ItemFn);
+    function.block.stmts.insert(0, parse_quote! {
+        let __perf_start = std::time::Instant::now();
+    });
+    function.block.stmts.push(parse_quote! {
+        unsafe {
+            #counter_type::write_perf(#name, __perf_start.elapsed().as_micros());
+        }
+    });
+    quote!(#function).into()
+}