New performance timings (#3096)

Co-authored-by: Laurenz <laurmaedje@gmail.com>

3 files changed, 93 insertions, 0 deletions

diff --git a/crates/typst-macros/src/lib.rs b/crates/typst-macros/src/lib.rs
index 28d02a6e..8ca7bcac 100644
--- a/crates/typst-macros/src/lib.rs
+++ b/crates/typst-macros/src/lib.rs
@@ -10,6 +10,7 @@ mod elem;
 mod func;
 mod scope;
 mod symbols;
+mod time;
 mod ty;
 
 use proc_macro::TokenStream as BoundaryStream;
@@ -342,3 +343,43 @@ pub fn symbols(stream: BoundaryStream) -> BoundaryStream {
         .unwrap_or_else(|err| err.to_compile_error())
         .into()
 }
+
+/// Times the function invokations.
+///
+/// When tracing is enabled in the typst-cli, this macro will record the
+/// invokations of the function and store them in a global map. The map can be
+/// accessed through the `typst_trace::RECORDER` static.
+///
+/// You can also specify the span of the function invokation:
+/// - `#[time(span = ..)]` to record the span, which will be used for the
+///   `EventKey`.
+///
+/// By default, all tracing is ommited using the `wasm32` target flag.
+/// This is done to avoid bloating the web app which doesn't need tracing.
+///
+/// ```ignore
+/// #[time]
+/// fn fibonacci(n: u64) -> u64 {
+///     if n <= 1 {
+///         1
+///     } else {
+///         fibonacci(n - 1) + fibonacci(n - 2)
+///     }
+/// }
+///
+/// #[time(span = span)]
+/// fn fibonacci_spanned(n: u64, span: Span) -> u64 {
+///     if n <= 1 {
+///         1
+///     } else {
+///         fibonacci(n - 1) + fibonacci(n - 2)
+///     }
+/// }
+/// ```
+#[proc_macro_attribute]
+pub fn time(stream: BoundaryStream, item: BoundaryStream) -> BoundaryStream {
+    let item = syn::parse_macro_input!(item as syn::ItemFn);
+    time::time(stream.into(), &item)
+        .unwrap_or_else(|err| err.to_compile_error())
+        .into()
+}
diff --git a/crates/typst-macros/src/time.rs b/crates/typst-macros/src/time.rs
new file mode 100644
index 00000000..fbe1ebc6
--- /dev/null
+++ b/crates/typst-macros/src/time.rs
@@ -0,0 +1,51 @@
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::parse::{Parse, ParseStream};
+use syn::Result;
+
+use crate::util::{kw, parse_key_value, parse_string};
+
+/// Expand the `#[time(..)]` macro.
+pub fn time(stream: TokenStream, item: &syn::ItemFn) -> Result<TokenStream> {
+    let meta: Meta = syn::parse2(stream)?;
+    Ok(create(meta, item))
+}
+
+/// The `..` in `#[time(..)]`.
+pub struct Meta {
+    pub span: Option<syn::Expr>,
+    pub name: Option<String>,
+}
+
+impl Parse for Meta {
+    fn parse(input: ParseStream) -> Result<Self> {
+        Ok(Self {
+            name: parse_string::<kw::name>(input)?,
+            span: parse_key_value::<kw::span, syn::Expr>(input)?,
+        })
+    }
+}
+
+fn create(meta: Meta, item: &syn::ItemFn) -> TokenStream {
+    let name = meta.name.unwrap_or_else(|| item.sig.ident.to_string());
+    let span = meta
+        .span
+        .as_ref()
+        .map(|span| quote! { Some(#span) })
+        .unwrap_or_else(|| quote! { None });
+
+    let sig = &item.sig;
+    let vis = &item.vis;
+    let block = &item.block;
+    quote! {
+        #vis #sig {
+            #[cfg(not(target_arch = "wasm32"))]
+            let __scope = ::typst_timing::TimingScope::new(#name, {
+                use ::typst::foundations::NativeElement;
+                #span
+            });
+
+            #block
+        }
+    }
+}
diff --git a/crates/typst-macros/src/util.rs b/crates/typst-macros/src/util.rs
index 32c0aa4e..4f7cc5fb 100644
--- a/crates/typst-macros/src/util.rs
+++ b/crates/typst-macros/src/util.rs
@@ -252,6 +252,7 @@ impl Parse for BareType {
 
 pub mod kw {
     syn::custom_keyword!(name);
+    syn::custom_keyword!(span);
     syn::custom_keyword!(title);
     syn::custom_keyword!(scope);
     syn::custom_keyword!(constructor);