Add benchmark

Author: bschoenmaeckers

pyo3-benches/benches/bench_pystring_from_fmt.rs

@@ -0,0 +1,27 @@
+use criterion::{criterion_group, criterion_main, Criterion};
+use pyo3::types::PyString;
+use pyo3::Python;
+use std::hint::black_box;
+
+fn bench_pystring_from_fmt(c: &mut Criterion) {
+    Python::attach(|py| {
+        c.bench_function("PyString::from_fmt simple", |b| {
+            b.iter(|| {
+                let format_args = format_args!("Hello {}!", "world");
+                let s = Ok(PyString::new(py, &format!("{format_args}")));
+                assert!(s.is_ok());
+            })
+        });
+        c.bench_function("PyString::from_fmt complex", |b| {
+            b.iter(|| {
+                let value = (black_box(42), black_box("foo"), [0; 0]);
+                let format_args = format_args!("This is some complex value: {value:?}");
+                let s = Ok(PyString::new(py, &format!("{format_args}")));
+                assert!(s.is_ok());
+            })
+        });
+    });
+}
+
+criterion_group!(benches, bench_pystring_from_fmt);
+criterion_main!(benches);