Avoid slowing down the CI too much with benchmarks

Runs the benchmarks faster (but with a lower statistical significance)
on CI.

Author: lovasoa

.travis.yml

@@ -12,7 +12,7 @@ env:
   - FEATURES="rayon"
 script:
   - cargo build --verbose --no-default-features --features "$FEATURES"
-  - cargo test --verbose --no-default-features --features "$FEATURES"
-  - cargo bench --verbose --no-default-features --features "$FEATURES"
+  - cargo test --tests --benches --no-default-features --features "$FEATURES"
+  - cargo bench --bench decoding_benchmark --no-default-features --features "$FEATURES" -- --warm-up-time 1 --measurement-time 1 --sample-size 25
 
 cache: cargo

Cargo.toml

@@ -17,7 +17,7 @@ rayon = { version = "1.0", optional = true }
 [dev-dependencies]
 png = "0.14"
 walkdir = "2.0"
-criterion = "0.2"
+criterion = "0.3"
 
 [[bench]]
 name = "decoding_benchmark"

appveyor.yml

@@ -16,5 +16,5 @@ build: false
 
 test_script:
   - cargo build --verbose
-  - cargo test --verbose
-  - cargo bench --verbose
+  - cargo test --tests --benches
+  - cargo bench --bench decoding_benchmark --no-default-features --features "$FEATURES" -- --warm-up-time 1 --measurement-time 1 --sample-size 25

benches/decoding_benchmark.rs

@@ -1,8 +1,7 @@
 extern crate criterion;
 extern crate jpeg_decoder;
 
-
-use criterion::{black_box, Criterion, criterion_group, criterion_main};
+use criterion::{black_box, Criterion};
 
 use jpeg_decoder as jpeg;
 use jpeg_decoder::ImageInfo;
@@ -17,7 +16,8 @@ fn read_metadata(image: &[u8]) -> ImageInfo {
     decoder.info().unwrap()
 }
 
-pub fn criterion_benchmark(c: &mut Criterion) {
+fn main() {
+    let mut c = Criterion::default().configure_from_args();
     c.bench_function("decode a 512x512 JPEG", |b| b.iter(|| {
         read_image(include_bytes!("tower.jpg"))
     }));
@@ -29,7 +29,5 @@ pub fn criterion_benchmark(c: &mut Criterion) {
     c.bench_function("extract metadata from an image", |b| b.iter(|| {
         read_metadata(include_bytes!("tower.jpg"))
     }));
-}
-
-criterion_group!(benches, criterion_benchmark);
-criterion_main!(benches);
+    c.final_summary();
+}