Added bench to read json

Cargo.toml

@@ -313,6 +313,10 @@ harness = false
 name = "write_json"
 harness = false
 
+[[bench]]
+name = "read_json"
+harness = false
+
 [[bench]]
 name = "slices_iterator"
 harness = false

benches/read_json.rs

@@ -0,0 +1,65 @@
+use arrow2::array::Array;
+use arrow2::datatypes::DataType;
+use criterion::{criterion_group, criterion_main, Criterion};
+
+use arrow2::io::json::{read, write};
+use arrow2::util::bench_util::*;
+
+fn prep(array: impl Array + 'static) -> (Vec<u8>, DataType) {
+    let mut data = vec![];
+    let blocks = write::Serializer::new(
+        vec![Ok(Box::new(array) as Box<dyn Array>)].into_iter(),
+        vec![],
+    );
+    // the operation of writing is IO-bounded.
+    write::write(&mut data, blocks).unwrap();
+
+    let dt = read::infer(&serde_json::from_slice(&data).unwrap()).unwrap();
+    (data, dt)
+}
+
+fn bench_read(data: &[u8], dt: &DataType) {
+    let json = serde_json::from_slice(data).unwrap();
+    read::deserialize(&json, dt.clone()).unwrap();
+}
+
+fn add_benchmark(c: &mut Criterion) {
+    (10..=20).step_by(2).for_each(|log2_size| {
+        let size = 2usize.pow(log2_size);
+
+        let array = create_primitive_array::<i32>(size, 0.1);
+
+        let (data, dt) = prep(array);
+
+        c.bench_function(&format!("read i32 2^{}", log2_size), |b| {
+            b.iter(|| bench_read(&data, &dt))
+        });
+
+        let array = create_primitive_array::<f64>(size, 0.1);
+
+        let (data, dt) = prep(array);
+
+        c.bench_function(&format!("read f64 2^{}", log2_size), |b| {
+            b.iter(|| bench_read(&data, &dt))
+        });
+
+        let array = create_string_array::<i32>(size, 10, 0.1, 42);
+
+        let (data, dt) = prep(array);
+
+        c.bench_function(&format!("read utf8 2^{}", log2_size), |b| {
+            b.iter(|| bench_read(&data, &dt))
+        });
+
+        let array = create_boolean_array(size, 0.1, 0.1);
+
+        let (data, dt) = prep(array);
+
+        c.bench_function(&format!("read bool 2^{}", log2_size), |b| {
+            b.iter(|| bench_read(&data, &dt))
+        });
+    })
+}
+
+criterion_group!(benches, add_benchmark);
+criterion_main!(benches);