Parallel Letter Frequency

rust/parallel-letter-frequency/benches/benchmark.rs

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+#![feature(test)]
+extern crate parallel_letter_frequency;
+extern crate test;
+
+use std::collections::HashMap;
+use test::Bencher;
+
+#[bench]
+fn bench_tiny_parallel(b: &mut Bencher) {
+    let tiny = &["a"];
+    b.iter(|| parallel_letter_frequency::frequency(tiny, 3));
+}
+
+#[bench]
+fn bench_tiny_sequential(b: &mut Bencher) {
+    let tiny = &["a"];
+    b.iter(|| frequency(tiny));
+}
+
+#[bench]
+fn bench_small_parallel(b: &mut Bencher) {
+    let texts = all_texts(1);
+    b.iter(|| parallel_letter_frequency::frequency(&texts, 3));
+}
+
+#[bench]
+fn bench_small_sequential(b: &mut Bencher) {
+    let texts = all_texts(1);
+    b.iter(|| frequency(&texts));
+}
+
+#[bench]
+fn bench_large_parallel(b: &mut Bencher) {
+    let texts = all_texts(30);
+    b.iter(|| parallel_letter_frequency::frequency(&texts, 3));
+}
+
+#[bench]
+fn bench_large_sequential(b: &mut Bencher) {
+    let texts = all_texts(30);
+    b.iter(|| frequency(&texts));
+}
+
+/// Simple sequential char frequency. Can it be beat?
+pub fn frequency(texts: &[&str]) -> HashMap<char, usize> {
+    let mut map = HashMap::new();
+
+    for line in texts {
+        for chr in line.chars().filter(|c| c.is_alphabetic()) {
+            if let Some(c) = chr.to_lowercase().next() {
+                (*map.entry(c).or_insert(0)) += 1;
+            }
+        }
+    }
+
+    map
+}
+
+fn all_texts(repeat: usize) -> Vec<&'static str> {
+    [ODE_AN_DIE_FREUDE, WILHELMUS, STAR_SPANGLED_BANNER]
+        .iter()
+        .cycle()
+        .take(3 * repeat)
+        .flat_map(|anthem| anthem.iter().cloned())
+        .collect()
+}
+
+// Poem by Friedrich Schiller. The corresponding music is the European Anthem.
+pub const ODE_AN_DIE_FREUDE: [&str; 8] = [
+    "Freude schöner Götterfunken",
+    "Tochter aus Elysium,",
+    "Wir betreten feuertrunken,",
+    "Himmlische, dein Heiligtum!",
+    "Deine Zauber binden wieder",
+    "Was die Mode streng geteilt;",
+    "Alle Menschen werden Brüder,",
+    "Wo dein sanfter Flügel weilt.",
+];
+
+// Dutch national anthem
+pub const WILHELMUS: [&str; 8] = [
+    "Wilhelmus van Nassouwe",
+    "ben ik, van Duitsen bloed,",
+    "den vaderland getrouwe",
+    "blijf ik tot in den dood.",
+    "Een Prinse van Oranje",
+    "ben ik, vrij, onverveerd,",
+    "den Koning van Hispanje",
+    "heb ik altijd geëerd.",
+];
+
+// American national anthem
+pub const STAR_SPANGLED_BANNER: [&str; 8] = [
+    "O say can you see by the dawn's early light,",
+    "What so proudly we hailed at the twilight's last gleaming,",
+    "Whose broad stripes and bright stars through the perilous fight,",
+    "O'er the ramparts we watched, were so gallantly streaming?",
+    "And the rockets' red glare, the bombs bursting in air,",
+    "Gave proof through the night that our flag was still there;",
+    "O say does that star-spangled banner yet wave,",
+    "O'er the land of the free and the home of the brave?",
+];