Add grep benchmarks and CodSpeed CI workflow

Add a divan-based benchmark suite (benches/grep_bench.rs) modeled on the
sed benchmarks, covering literal/fixed-string/regex search, case-insensitive
matching, counting, inversion, line numbers, word/whole-line matching, and
quiet mode. Wire up the dev-dependencies (codspeed-divan-compat, tempfile,
uucore benchmark feature) and a [[bench]] entry.

Add a Benchmarks GitHub Actions workflow running the suite through CodSpeed,
adapted from the sed setup.

benches/grep_bench.rs

@@ -0,0 +1,255 @@
+// Benchmarks for the grep utility
+//
+// SPDX-License-Identifier: MIT
+//
+// This file is part of the uutils grep package.
+// It is licensed under the MIT License.
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+use divan::{Bencher, black_box};
+use uu_grep::uumain;
+use uucore::benchmark::{create_test_file, run_util_function};
+
+/// Build an access-log-like data set with `n` lines.
+///
+/// Roughly a quarter of the lines use a non-default HTTP method / status /
+/// user-agent so that selective patterns match a realistic subset rather than
+/// every line or no line at all.
+fn access_log(n: usize) -> Vec<u8> {
+    let mut data = Vec::new();
+    for i in 0..n {
+        let method = if i % 4 == 0 { "POST" } else { "GET" };
+        let status = if i % 7 == 0 { 404 } else { 200 };
+        let agent = if i % 3 == 0 {
+            "Mozilla/5.0 (X11; Linux x86_64) Chrome/120.0"
+        } else {
+            "curl/8.5.0"
+        };
+        let line = format!(
+            "192.168.{}.{} - - [01/Jan/2024:00:00:00 +0000] \"{} /index.html HTTP/1.1\" {} 1234 \"-\" \"{}\"\n",
+            (i / 256) % 256,
+            i % 256,
+            method,
+            status,
+            agent,
+        );
+        data.extend_from_slice(line.as_bytes());
+    }
+    data
+}
+
+/// Benchmark a literal search that matches nothing.
+///
+/// This is the purest measure of raw scan throughput: the whole file is read
+/// and searched but no output is produced.
+#[divan::bench]
+fn literal_no_match(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(2_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(
+            uumain,
+            &["ZZZ_NONEXISTENT_PATTERN_ZZZ", file_path_str],
+        ));
+    });
+}
+
+/// Benchmark a literal search that matches a subset of lines.
+#[divan::bench]
+fn literal_match_some(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(2_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &["POST", file_path_str]));
+    });
+}
+
+/// Benchmark a literal search that matches every line (counting only).
+///
+/// `-c` keeps the output bounded so the benchmark measures matching rather than
+/// terminal I/O.
+#[divan::bench]
+fn literal_match_all_count(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(2_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &["-c", "HTTP", file_path_str]));
+    });
+}
+
+/// Benchmark a fixed-string search (`-F`).
+#[divan::bench]
+fn fixed_string(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(2_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(
+            uumain,
+            &["-F", "Chrome/120.0", file_path_str],
+        ));
+    });
+}
+
+/// Benchmark a case-insensitive search (`-i`).
+#[divan::bench]
+fn case_insensitive(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(2_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &["-i", "mozilla", file_path_str]));
+    });
+}
+
+/// Benchmark counting matches (`-c`).
+#[divan::bench]
+fn count(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(2_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &["-c", "POST", file_path_str]));
+    });
+}
+
+/// Benchmark an inverted match (`-v`).
+///
+/// Most lines do not contain "POST", so this selects the majority of lines;
+/// `-c` bounds the output.
+#[divan::bench]
+fn invert_match_count(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(2_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &["-vc", "POST", file_path_str]));
+    });
+}
+
+/// Benchmark printing line numbers (`-n`).
+#[divan::bench]
+fn line_number(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(1_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &["-nc", "POST", file_path_str]));
+    });
+}
+
+/// Benchmark word-boundary matching (`-w`).
+#[divan::bench]
+fn word_match(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(2_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &["-wc", "GET", file_path_str]));
+    });
+}
+
+/// Benchmark an extended regular expression with alternation (`-E`).
+#[divan::bench]
+fn extended_regex(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(2_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(
+            uumain,
+            &["-Ec", "(POST|DELETE|PUT)", file_path_str],
+        ));
+    });
+}
+
+/// Benchmark a basic regular expression with an anchor and character class.
+#[divan::bench]
+fn basic_regex(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(2_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(
+            uumain,
+            &["-c", "^192\\.168\\.[0-9]*\\.0 ", file_path_str],
+        ));
+    });
+}
+
+/// Benchmark a Perl-compatible regular expression (`-P`).
+#[divan::bench]
+fn perl_regex(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(2_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(
+            uumain,
+            &["-Pc", "\"\\d{3}\" \\d+", file_path_str],
+        ));
+    });
+}
+
+/// Benchmark `--only-matching` (`-o`) extracting a substring from each line.
+#[divan::bench]
+fn only_matching(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(1_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(
+            uumain,
+            &["-Eoc", "[0-9]+\\.[0-9]+\\.[0-9]+\\.[0-9]+", file_path_str],
+        ));
+    });
+}
+
+/// Benchmark quiet mode (`-q`), which can stop at the first match.
+#[divan::bench]
+fn quiet_first_match(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let file_path = create_test_file(&access_log(2_000_000), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &["-q", "POST", file_path_str]));
+    });
+}
+
+/// Benchmark searching short numeric lines (many small lines).
+#[divan::bench]
+fn short_lines(bencher: Bencher) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let mut data = Vec::new();
+    for i in 0..10_000_000 {
+        data.extend_from_slice(format!("{i}\n").as_bytes());
+    }
+    let file_path = create_test_file(&data, temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &["-c", "999", file_path_str]));
+    });
+}
+
+fn main() {
+    divan::main();
+}