adds benchmark for reconstruct

Cargo.toml

@@ -50,3 +50,6 @@ quickcheck = "0.9"
 
 [build-dependencies]
 cc = { version = "1.0", optional = true }
+
+[[bench]]
+name = "reconstruct"

benches/reconstruct.rs

@@ -0,0 +1,108 @@
+#![feature(test)]
+
+extern crate test;
+
+use {
+    rand::{prelude::*, Rng},
+    reed_solomon_erasure::galois_8::Field,
+    test::Bencher,
+};
+
+type ReedSolomon = reed_solomon_erasure::ReedSolomon<Field>;
+
+const SHARD_SIZE: usize = 1024;
+
+fn run_reconstruct_bench(bencher: &mut Bencher, num_data_shards: usize, num_parity_shards: usize) {
+    let mut rng = rand::thread_rng();
+    let mut shards = vec![vec![0u8; SHARD_SIZE]; num_data_shards + num_parity_shards];
+    for shard in &mut shards[..num_data_shards] {
+        rng.fill(&mut shard[..]);
+    }
+    let reed_solomon = ReedSolomon::new(num_data_shards, num_parity_shards).unwrap();
+    reed_solomon.encode(&mut shards[..]).unwrap();
+    let shards: Vec<_> = shards.into_iter().map(Some).collect();
+
+    bencher.iter(|| {
+        let mut shards = shards.clone();
+        for _ in 0..num_parity_shards {
+            *shards.choose_mut(&mut rng).unwrap() = None;
+        }
+        reed_solomon.reconstruct(&mut shards[..]).unwrap();
+        assert!(shards.iter().all(Option::is_some));
+    });
+}
+
+#[bench]
+fn bench_reconstruct_2_2(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 2, 2)
+}
+
+#[bench]
+fn bench_reconstruct_4_2(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 4, 2)
+}
+
+#[bench]
+fn bench_reconstruct_4_4(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 4, 4)
+}
+
+#[bench]
+fn bench_reconstruct_8_2(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 8, 2)
+}
+
+#[bench]
+fn bench_reconstruct_8_4(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 8, 4)
+}
+
+#[bench]
+fn bench_reconstruct_8_8(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 8, 8)
+}
+
+#[bench]
+fn bench_reconstruct_16_2(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 16, 2)
+}
+
+#[bench]
+fn bench_reconstruct_16_4(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 16, 4)
+}
+
+#[bench]
+fn bench_reconstruct_16_8(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 16, 8)
+}
+
+#[bench]
+fn bench_reconstruct_16_16(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 16, 16)
+}
+
+#[bench]
+fn bench_reconstruct_32_2(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 32, 2)
+}
+
+#[bench]
+fn bench_reconstruct_32_4(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 32, 4)
+}
+
+#[bench]
+fn bench_reconstruct_32_8(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 32, 8)
+}
+
+#[bench]
+fn bench_reconstruct_32_16(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 32, 16)
+}
+
+#[bench]
+fn bench_reconstruct_32_32(bencher: &mut Bencher) {
+    run_reconstruct_bench(bencher, 32, 32)
+}