resurrect bench

*   fix compilation, which broke with 9093549. Criterion changed
    Throughput::Bytes to take a u64 rather than a u32 as part of the
    0.2 -> 0.3 update.
*   build on CI so this doesn't break again.
*   add instructions for generating input data, and .gitignore it.
*   fix warnings.

Author: scottlamb

.github/workflows/rust.yml

@@ -14,6 +14,6 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - name: Build
-      run: cargo build --verbose
+      run: cargo build --verbose --all-targets
     - name: Run tests
       run: cargo test --verbose

.gitignore

@@ -1,3 +1,5 @@
+/big_buck_bunny_1080p_h264.mov
+/big_buck_bunny_1080p.h264
 /target/
 **/*.swp
 Cargo.lock

benches/bench.rs

@@ -1,11 +1,19 @@
+//! Benchmark on a large video file.
+//!
+//! Expects a copy of [Big Buck Bunny](https://peach.blender.org/download/):
+//! ```text
+//! $ curl --OL https://download.blender.org/peach/bigbuckbunny_movies/big_buck_bunny_1080p_h264.mov
+//! $ ffmpeg -i big_buck_bunny_1080p_h264.mov -c copy big_buck_bunny_1080p.h264
+//! ```
+
 #[macro_use]
 extern crate criterion;
 extern crate h264_reader;
 
 use criterion::Criterion;
 use std::fs::File;
-use criterion::Benchmark;
 use criterion::Throughput;
+use std::convert::TryFrom;
 use std::io::Read;
 use h264_reader::annexb::AnnexBReader;
 use h264_reader::annexb::NalReader;
@@ -33,7 +41,7 @@ impl NalHandler for NullNalHandler {
 }
 
 struct NullNalReader {
-    decoder: RbspDecoder<NullNalHandler>,
+    _decoder: RbspDecoder<NullNalHandler>,
     start: u64,
     push: u64,
     end: u64,
@@ -53,26 +61,29 @@ impl NalReader for NullNalReader {
 }
 
 fn h264_reader(c: &mut Criterion) {
-    let mut f = File::open("big_buck_bunny_1080p_24fps_h264.h264").expect("file not found");
-    let size = f.metadata().unwrap().len() as usize;
-    let mut buf = vec![0; size];
+    let mut f = File::open("big_buck_bunny_1080p.h264").expect("file not found");
+    let len = f.metadata().unwrap().len();
+    let mut buf = vec![0; usize::try_from(len).unwrap()];
     f.read(&mut buf[..]).unwrap();
     let mut ctx = Context::default();
     let nal_handler = NullNalHandler {};
     let nal_reader = NullNalReader {
-        decoder: RbspDecoder::new(nal_handler),
+        _decoder: RbspDecoder::new(nal_handler),
         start: 0,
         push: 0,
         end: 0,
     };
     let mut annexb_reader = AnnexBReader::new(nal_reader);
-    c.bench("parse", Benchmark::new("parse", move |b| {
+
+    let mut group = c.benchmark_group("parse");
+    group.throughput(Throughput::Bytes(len));
+    group.bench_function("parse", move |b| {
         b.iter(|| {
             annexb_reader.start(&mut ctx);
             annexb_reader.push(&mut ctx, &buf[..]);
             annexb_reader.end_units(&mut ctx);
-        } );
-    }).throughput(Throughput::Bytes(size as u32)));
+        })
+    });
 }
 
 criterion_group!(benches, h264_reader);