ARROW-11651: [Rust][DataFusion] Implement Postgres String Functions: Length Functions

Splitting up apache/arrow#9243

This implements the following functions:

- String functions
  - [x] bit_Length
  - [x] char_length
  - [x] character_length
  - [x] length
  - [x] octet_length

Closes #9509 from seddonm1/length-functions

Lead-authored-by: Mike Seddon <seddonm1@gmail.com>
Co-authored-by: Jorge C. Leitao <jorgecarleitao@gmail.com>
Signed-off-by: Andrew Lamb <andrew@nerdnetworks.org>

Author: 2 people

rust/arrow/Cargo.toml

@@ -114,6 +114,10 @@ harness = false
 name = "length_kernel"
 harness = false
 
+[[bench]]
+name = "bit_length_kernel"
+harness = false
+
 [[bench]]
 name = "sort_kernel"
 harness = false

rust/arrow/benches/bit_length_kernel.rs

@@ -0,0 +1,46 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#[macro_use]
+extern crate criterion;
+use criterion::Criterion;
+
+extern crate arrow;
+
+use arrow::{array::*, compute::kernels::length::bit_length};
+
+fn bench_bit_length(array: &StringArray) {
+    criterion::black_box(bit_length(array).unwrap());
+}
+
+fn add_benchmark(c: &mut Criterion) {
+    fn double_vec<T: Clone>(v: Vec<T>) -> Vec<T> {
+        [&v[..], &v[..]].concat()
+    }
+
+    // double ["hello", " ", "world", "!"] 10 times
+    let mut values = vec!["one", "on", "o", ""];
+    for _ in 0..10 {
+        values = double_vec(values);
+    }
+    let array = StringArray::from(values);
+
+    c.bench_function("bit_length", |b| b.iter(|| bench_bit_length(&array)));
+}
+
+criterion_group!(benches, add_benchmark);
+criterion_main!(benches);