add merge_archive benchmarks

Cargo.toml

@@ -87,3 +87,7 @@ harness = false
 [[bench]]
 name = "read_metadata"
 harness = false
+
+[[bench]]
+name = "merge_archive"
+harness = false

benches/merge_archive.rs

@@ -0,0 +1,120 @@
+use bencher::{benchmark_group, benchmark_main};
+
+use std::io::{Cursor, Read, Seek, Write};
+
+use bencher::Bencher;
+use getrandom::getrandom;
+use zip::{result::ZipResult, write::SimpleFileOptions, ZipArchive, ZipWriter};
+
+fn generate_random_archive(
+    num_entries: usize,
+    entry_size: usize,
+    options: SimpleFileOptions,
+) -> ZipResult<(usize, ZipArchive<Cursor<Vec<u8>>>)> {
+    let buf = Cursor::new(Vec::new());
+    let mut zip = ZipWriter::new(buf);
+
+    let mut bytes = vec![0u8; entry_size];
+    for i in 0..num_entries {
+        let name = format!("random{}.dat", i);
+        zip.start_file(name, options)?;
+        getrandom(&mut bytes).unwrap();
+        zip.write_all(&bytes)?;
+    }
+
+    let buf = zip.finish()?.into_inner();
+    let len = buf.len();
+
+    Ok((len, ZipArchive::new(Cursor::new(buf))?))
+}
+
+fn perform_merge<R: Read + Seek, W: Write + Seek>(
+    src: ZipArchive<R>,
+    mut target: ZipWriter<W>,
+) -> ZipResult<ZipWriter<W>> {
+    target.merge_archive(src)?;
+    Ok(target)
+}
+
+fn perform_raw_copy_file<R: Read + Seek, W: Write + Seek>(
+    mut src: ZipArchive<R>,
+    mut target: ZipWriter<W>,
+) -> ZipResult<ZipWriter<W>> {
+    for i in 0..src.len() {
+        let entry = src.by_index(i)?;
+        target.raw_copy_file(entry)?;
+    }
+    Ok(target)
+}
+
+const NUM_ENTRIES: usize = 100;
+const ENTRY_SIZE: usize = 1024;
+
+fn merge_archive_stored(bench: &mut Bencher) {
+    let options = SimpleFileOptions::default().compression_method(zip::CompressionMethod::Stored);
+    let (len, src) = generate_random_archive(NUM_ENTRIES, ENTRY_SIZE, options).unwrap();
+
+    bench.bytes = len as u64;
+
+    bench.iter(|| {
+        let buf = Cursor::new(Vec::new());
+        let zip = ZipWriter::new(buf);
+        let mut zip = perform_merge(src.clone(), zip).unwrap();
+        let buf = zip.finish().unwrap().into_inner();
+        assert_eq!(buf.len(), len);
+    });
+}
+
+fn merge_archive_compressed(bench: &mut Bencher) {
+    let options = SimpleFileOptions::default().compression_method(zip::CompressionMethod::Deflated);
+    let (len, src) = generate_random_archive(NUM_ENTRIES, ENTRY_SIZE, options).unwrap();
+
+    bench.bytes = len as u64;
+
+    bench.iter(|| {
+        let buf = Cursor::new(Vec::new());
+        let zip = ZipWriter::new(buf);
+        let mut zip = perform_merge(src.clone(), zip).unwrap();
+        let buf = zip.finish().unwrap().into_inner();
+        assert_eq!(buf.len(), len);
+    });
+}
+
+fn merge_archive_raw_copy_file_stored(bench: &mut Bencher) {
+    let options = SimpleFileOptions::default().compression_method(zip::CompressionMethod::Stored);
+    let (len, src) = generate_random_archive(NUM_ENTRIES, ENTRY_SIZE, options).unwrap();
+
+    bench.bytes = len as u64;
+
+    bench.iter(|| {
+        let buf = Cursor::new(Vec::new());
+        let zip = ZipWriter::new(buf);
+        let mut zip = perform_raw_copy_file(src.clone(), zip).unwrap();
+        let buf = zip.finish().unwrap().into_inner();
+        assert_eq!(buf.len(), len);
+    });
+}
+
+fn merge_archive_raw_copy_file_compressed(bench: &mut Bencher) {
+    let options = SimpleFileOptions::default().compression_method(zip::CompressionMethod::Deflated);
+    let (len, src) = generate_random_archive(NUM_ENTRIES, ENTRY_SIZE, options).unwrap();
+
+    bench.bytes = len as u64;
+
+    bench.iter(|| {
+        let buf = Cursor::new(Vec::new());
+        let zip = ZipWriter::new(buf);
+        let mut zip = perform_raw_copy_file(src.clone(), zip).unwrap();
+        let buf = zip.finish().unwrap().into_inner();
+        assert_eq!(buf.len(), len);
+    });
+}
+
+benchmark_group!(
+    benches,
+    merge_archive_stored,
+    merge_archive_compressed,
+    merge_archive_raw_copy_file_stored,
+    merge_archive_raw_copy_file_compressed,
+);
+benchmark_main!(benches);