chore: add bench to illustrate diff

benchmarks/Cargo.toml

@@ -36,5 +36,9 @@ harness = false
 name = "maps_sets_inner_de"
 harness = false
 
+[[bench]]
+name = "object_length"
+harness = false
+
 [features]
 default = ["borsh/std", "borsh/derive"]

benchmarks/benches/object_length.rs

@@ -0,0 +1,55 @@
+use benchmarks::{Generate, ValidatorStake};
+use borsh::{to_vec, BorshDeserialize, BorshSerialize};
+use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion, Throughput};
+use rand::SeedableRng;
+
+fn ser_obj_length<T>(group_name: &str, num_samples: usize, c: &mut Criterion)
+where
+    for<'a> T: Generate + BorshSerialize + BorshDeserialize + 'static,
+{
+    let mut rng = rand_xorshift::XorShiftRng::from_seed([0u8; 16]);
+    let mut group = c.benchmark_group(group_name);
+
+    let objects: Vec<_> = (0..num_samples).map(|_| T::generate(&mut rng)).collect();
+    let borsh_datas: Vec<Vec<u8>> = objects.iter().map(|t| to_vec(t).unwrap()).collect();
+    let borsh_sizes: Vec<_> = borsh_datas.iter().map(|d| d.len()).collect();
+
+    for i in 0..objects.len() {
+        let size = borsh_sizes[i];
+        let obj = &objects[i];
+        assert_eq!(
+            borsh::to_vec(obj).unwrap().len(),
+            borsh::object_length(obj).unwrap()
+        );
+
+        let benchmark_param_display = format!("idx={}; size={}", i, size);
+
+        group.throughput(Throughput::Bytes(size as u64));
+        group.bench_with_input(
+            BenchmarkId::new(
+                "borsh::to_vec(obj).unwrap().len()",
+                benchmark_param_display.clone(),
+            ),
+            obj,
+            |b, d| {
+                b.iter(|| borsh::to_vec(d).unwrap().len());
+            },
+        );
+        group.bench_with_input(
+            BenchmarkId::new(
+                "borsh::object_length(obj).unwrap()",
+                benchmark_param_display.clone(),
+            ),
+            obj,
+            |b, d| {
+                b.iter(|| borsh::object_length(d).unwrap());
+            },
+        );
+    }
+    group.finish();
+}
+fn ser_length_validator_stake(c: &mut Criterion) {
+    ser_obj_length::<ValidatorStake>("ser_account", 3, c);
+}
+criterion_group!(ser_length, ser_length_validator_stake,);
+criterion_main!(ser_length);