Add more writeable benches and put them in README

utils/writeable/benches/writeable.rs

@@ -148,6 +148,33 @@ fn writeable_benches(c: &mut Criterion) {
             })
         });
     });
+    c.bench_function("writeable/write_to/short", |b| {
+        b.iter(|| {
+            let mut buf = String::with_capacity(500);
+            WriteableMessage {
+                message: black_box(SHORT_STR),
+            }
+            .write_to(&mut buf)
+        });
+    });
+    c.bench_function("writeable/write_to/medium", |b| {
+        b.iter(|| {
+            let mut buf = String::with_capacity(500);
+            WriteableMessage {
+                message: black_box(MEDIUM_STR),
+            }
+            .write_to(&mut buf)
+        });
+    });
+    c.bench_function("writeable/write_to/long", |b| {
+        b.iter(|| {
+            let mut buf = String::with_capacity(500);
+            WriteableMessage {
+                message: black_box(LONG_STR),
+            }
+            .write_to(&mut buf)
+        });
+    });
 }
 
 #[cfg(feature = "bench")]
@@ -209,6 +236,33 @@ fn display_benches(c: &mut Criterion) {
             .to_string()
         });
     });
+    c.bench_function("display/fmt/short", |b| {
+        b.iter(|| {
+            use std::io::Write;
+            let mut buf = Vec::<u8>::with_capacity(500);
+            write!(&mut buf, "{}", DisplayMessage {
+                message: black_box(SHORT_STR),
+            })
+        });
+    });
+    c.bench_function("display/fmt/medium", |b| {
+        b.iter(|| {
+            use std::io::Write;
+            let mut buf = Vec::<u8>::with_capacity(500);
+            write!(&mut buf, "{}", DisplayMessage {
+                message: black_box(MEDIUM_STR),
+            })
+        });
+    });
+    c.bench_function("display/fmt/long", |b| {
+        b.iter(|| {
+            use std::io::Write;
+            let mut buf = Vec::<u8>::with_capacity(500);
+            write!(&mut buf, "{}", DisplayMessage {
+                message: black_box(LONG_STR),
+            })
+        });
+    });
 }
 
 #[cfg(feature = "bench")]
@@ -244,6 +298,19 @@ fn complex_benches(c: &mut Criterion) {
                 .map(|s| writeable::cmp_str(black_box(&COMPLEX_WRITEABLE_MEDIUM), s))
         });
     });
+    c.bench_function("complex/write_to/medium", |b| {
+        b.iter(|| {
+            let mut buf = String::with_capacity(500);
+            black_box(COMPLEX_WRITEABLE_MEDIUM).write_to(&mut buf)
+        });
+    });
+    c.bench_function("complex/fmt/medium", |b| {
+        b.iter(|| {
+            use std::io::Write;
+            let mut buf = Vec::<u8>::with_capacity(500);
+            write!(&mut buf, "{}", black_box(COMPLEX_WRITEABLE_MEDIUM))
+        })
+    });
 }
 
 criterion_group!(benches, overview_bench,);

utils/writeable/src/lib.rs

@@ -17,9 +17,7 @@
     )
 )]
 
-//! `writeable` is a utility crate of the [`ICU4X`] project.
-//!
-//! It includes [`Writeable`], a core trait representing an object that can be written to a
+//! This crate defines [`Writeable`], a trait representing an object that can be written to a
 //! sink implementing `std::fmt::Write`. It is an alternative to `std::fmt::Display` with the
 //! addition of a function indicating the number of bytes to be written.
 //!
@@ -28,6 +26,18 @@
 //! 1. More efficient, since the sink can pre-allocate bytes.
 //! 2. Smaller code, since the format machinery can be short-circuited.
 //!
+//! This crate also exports [`TryWriteable`], a writeable that supports a custom error.
+//!
+//! # Benchmarks
+//!
+//! The benchmarks to generate the following data can be found in the `benches` directory.
+//!
+//! | Case | `Writeable` | `Display` |
+//! |---|---|---|
+//! | Create string from single-string message (139 chars) | 19.999 ns | 22.133 ns |
+//! | Create string from complex message | 35.838 ns | 87.703 ns |
+//! | Write complex message to buffer | 56.855 ns | 64.971 ns |
+//!
 //! # Examples
 //!
 //! ```