feat(divan_compat): share instance of codspeed helper across benches

Author: GuillaumeLagrange

crates/divan_compat/src/compat/bench/mod.rs

@@ -11,7 +11,7 @@ pub use self::{
 };
 
 use codspeed::codspeed::CodSpeed;
-use std::{cell::RefCell, rc::Rc};
+use std::cell::RefCell;
 
 /// Using this in place of `()` for `GenI` prevents `Bencher::with_inputs` from
 /// working with `()` unintentionally.
@@ -23,18 +23,18 @@ pub struct BencherConfig<GenI = Unit> {
 }
 
 pub struct Bencher<'a, 'b, C = BencherConfig> {
-    pub(crate) codspeed: Rc<RefCell<CodSpeed>>,
+    pub(crate) codspeed: &'a RefCell<CodSpeed>,
     pub(crate) uri: String,
     pub(crate) config: C,
-    pub(crate) _marker: std::marker::PhantomData<&'a &'b ()>,
+    pub(crate) _marker: std::marker::PhantomData<&'b ()>,
 }
 
 #[allow(clippy::needless_lifetimes)]
 impl<'a, 'b> Bencher<'a, 'b> {
-    pub(crate) fn new(uri: String) -> Self {
+    pub(crate) fn new(codspeed: &'a RefCell<CodSpeed>, uri: String) -> Self {
         Self {
-            codspeed: Rc::new(RefCell::new(CodSpeed::new())),
             config: BencherConfig { gen_input: Unit },
+            codspeed,
             uri,
             _marker: std::marker::PhantomData,
         }

crates/divan_compat/src/compat/mod.rs

@@ -14,7 +14,10 @@ mod entry;
 mod uri;
 mod util;
 
+use std::{cell::RefCell, rc::Rc};
+
 pub use bench::*;
+use codspeed::codspeed::CodSpeed;
 
 pub fn main() {
     // Outlined steps of original divan::main and their equivalent in codspeed instrumented mode
@@ -31,6 +34,7 @@ pub fn main() {
     // filtering is managed by the `cargo-codspeed` wrappers before we reach this point.
 
     // 4. Scan the tree and execute benchmarks
+    let codspeed = Rc::new(RefCell::new(CodSpeed::new()));
     for entry in bench_entries.iter() {
         let entry_uri = uri::generate(entry.meta.display_name, &entry.meta);
 
@@ -42,14 +46,14 @@ pub fn main() {
         }
         match entry.bench {
             entry::BenchEntryRunner::Plain(bench_fn) => {
-                bench_fn(bench::Bencher::new(entry_uri));
+                bench_fn(bench::Bencher::new(&codspeed, entry_uri));
             }
             entry::BenchEntryRunner::Args(bench_runner) => {
                 let bench_runner = bench_runner();
 
                 for (arg_index, arg_name) in bench_runner.arg_names().iter().enumerate() {
                     let uri_with_arg = uri::append_arg(entry_uri.as_str(), arg_name);
-                    let bencher = bench::Bencher::new(uri_with_arg);
+                    let bencher = bench::Bencher::new(&codspeed, uri_with_arg);
 
                     bench_runner.bench(bencher, arg_index);
                 }