Add benchmarks to compare different structures

Cargo.toml

@@ -1,16 +1,21 @@
+[[bench]]
+harness = false
+name = "comparison"
+path = "benches/comparison.rs"
+
 [package]
 authors = ["Paul Mason <paul@form1.co.nz>"]
 categories = ["science","data-structures"]
 description = "A Decimal Implementation written in pure Rust suitable for financial calculations."
 documentation = "https://docs.rs/rust_decimal/"
 edition = "2018"
+exclude = [ "tests/generated/*" ]
 keywords = ["decimal","financial","fixed","precision"]
 license = "MIT"
 name = "rust_decimal"
 readme = "./README.md"
 repository = "https://github.com/paupino/rust-decimal"
 version = "1.15.0"
-exclude = [ "tests/generated/*" ]
 
 [package.metadata.docs.rs]
 all-features = true
@@ -30,6 +35,7 @@ tokio-postgres = { default-features = false, optional = true, version = "0.7" }
 [dev-dependencies]
 bincode = "1.3"
 bytes = "1.0"
+criterion = { default-features = false, version = "0.3" }
 csv = "1"
 futures = "0.3"
 serde_derive = "1.0"
@@ -46,10 +52,10 @@ legacy-ops = []
 maths = []
 maths-nopanic = ["maths"]
 rust-fuzz = ["arbitrary"]
+serde-arbitrary-precision = ["serde", "serde_json/arbitrary_precision"]
 serde-bincode = ["serde-str"] # Backwards compatability
 serde-float = ["serde"]
 serde-str = ["serde"]
-serde-arbitrary-precision = ["serde", "serde_json/arbitrary_precision"]
 std = ["arrayvec/std"]
 tokio-pg = ["db-tokio-postgres"] # Backwards compatability
 

benches/comparison.rs

@@ -0,0 +1,50 @@
+//! See how `rust-decimal` performs compared to native floating numbers.
+
+use criterion::{
+    black_box, criterion_group, criterion_main, measurement::Measurement, BenchmarkGroup, BenchmarkId, Criterion,
+};
+use rust_decimal::Decimal;
+
+const DECIMAL_2_01: Decimal = Decimal::from_parts(201, 0, 0, false, 2);
+const DECIMAL_13_7: Decimal = Decimal::from_parts(137, 0, 0, false, 1);
+const F64_2_01: f64 = 2.01;
+const F64_13_7: f64 = 13.7;
+
+macro_rules! add_benchmark_group {
+    ($criterion:expr, $f:ident, $op:tt) => {
+        fn $f<M, const N: usize>(group: &mut BenchmarkGroup<'_, M>)
+        where
+            M: Measurement,
+        {
+            group.bench_with_input(BenchmarkId::new("f64 (diff)", N), &N, |ben, _| {
+                ben.iter(|| black_box(F64_2_01 $op F64_13_7))
+            });
+
+            group.bench_with_input(BenchmarkId::new("f64 (equal)", N), &N, |ben, _| {
+                ben.iter(|| black_box(F64_2_01 $op F64_2_01))
+            });
+
+            group.bench_with_input(BenchmarkId::new("rust-decimal (diff)", N), &N, |ben, _| {
+                ben.iter(|| black_box(DECIMAL_2_01 $op DECIMAL_13_7))
+            });
+
+            group.bench_with_input(BenchmarkId::new("rust-decimal (equal)", N), &N, |ben, _| {
+                ben.iter(|| black_box(DECIMAL_2_01 $op DECIMAL_2_01))
+            });
+        }
+
+        let mut group = $criterion.benchmark_group(stringify!($f));
+        $f::<_, 100>(&mut group);
+        group.finish();
+    };
+}
+
+fn criterion_benchmark(c: &mut Criterion) {
+    add_benchmark_group!(c, addition, +);
+    add_benchmark_group!(c, division, /);
+    add_benchmark_group!(c, multiplication, *);
+    add_benchmark_group!(c, subtraction, -);
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);