Benchmark parallel-letter-frequency. Closes exercism#244

Author: glennpratt

.travis.yml

@@ -8,11 +8,13 @@ sudo: false
 rust:
   - stable
   - beta
-  - nightly
 env:
   - DENYWARNINGS=
   - DENYWARNINGS=1
 matrix:
+  include:
+    - rust: nightly
+      env: BENCHMARK=1
   allow_failures:
     - rust: nightly
     - rust: beta

_test/check-exercises.sh

@@ -51,6 +51,11 @@ for exercise in exercises/*/tests; do
             # Run the test and get the status
             cargo test
         fi
+
+        # Run benchmarks if present.
+        if [ -n "$BENCHMARK" ] && [ -d benches ]; then
+            cargo bench
+        fi
     )
 
     status=$?

exercises/parallel-letter-frequency/Cargo.lock

@@ -1,3 +1,6 @@
 [package]
 name = "parallel-letter-frequency"
 version = "0.0.0"
+
+[dev-dependencies]
+sequential-letter-frequency = { path = "sequential-letter-frequency" }

exercises/parallel-letter-frequency/Cargo.toml

@@ -0,0 +1,24 @@
+#![feature(test)]
+extern crate parallel_letter_frequency;
+extern crate sequential_letter_frequency;
+extern crate test;
+
+use sequential_letter_frequency::*;
+use test::Bencher;
+
+#[bench]
+fn bench_sequential(b: &mut Bencher) {
+    b.iter(|| sequential_letter_frequency::frequency(&all_texts()));
+}
+
+#[bench]
+fn bench_parallel(b: &mut Bencher) {
+    b.iter(|| parallel_letter_frequency::frequency(&all_texts(), 3));
+}
+
+fn all_texts() -> Vec<&'static str> {
+    [ODE_AN_DIE_FREUDE, WILHELMUS, STAR_SPANGLED_BANNER]
+        .iter()
+        .flat_map(|anthem| anthem.iter().cloned())
+        .collect()
+}

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

@@ -0,0 +1 @@
+!**src

exercises/parallel-letter-frequency/sequential-letter-frequency/.gitignore

@@ -0,0 +1,3 @@
+[package]
+name = "sequential-letter-frequency"
+version = "0.0.0"

exercises/parallel-letter-frequency/sequential-letter-frequency/Cargo.toml

@@ -0,0 +1,49 @@
+use std::collections::HashMap;
+
+/// 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
+}
+
+// Poem by Friedrich Schiller. The corresponding music is the European Anthem.
+pub const ODE_AN_DIE_FREUDE: [&'static 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: [&'static 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: [&'static 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?"];

exercises/parallel-letter-frequency/sequential-letter-frequency/src/lib.rs

@@ -1,39 +1,9 @@
 use std::collections::HashMap;
 
 extern crate parallel_letter_frequency as frequency;
+extern crate sequential_letter_frequency;
 
-// Poem by Friedrich Schiller. The corresponding music is the European Anthem.
-const ODE_AN_DIE_FREUDE: [&'static 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
-const WILHELMUS: [&'static 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
-const STAR_SPANGLED_BANNER: [&'static 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?"];
+use sequential_letter_frequency::*;
 
 #[test]
 fn test_no_texts() {
@@ -121,3 +91,16 @@ fn test_all_three_anthems_3_workers() {
     assert_eq!(freqs.get(&'t'), Some(&56));
     assert_eq!(freqs.get(&'ü'), Some(&2));
 }
+
+#[test]
+fn test_matches_sequential() {
+    let mut v = Vec::new();
+    for anthem in [ODE_AN_DIE_FREUDE, WILHELMUS, STAR_SPANGLED_BANNER].iter() {
+        for line in anthem.iter() {
+            v.push(*line);
+        }
+    }
+    let freqs = frequency::frequency(&v[..], 3);
+    let ref_freqs = sequential_letter_frequency::frequency(&v[..]);
+    assert_eq!(freqs, ref_freqs);
+}