FEAT: Benchmarks for arraystring.try_push / push

These benches inform encode_utf8 changes, if any.

Cargo.toml

@@ -32,6 +32,10 @@ bencher = "0.1.4"
 name = "extend"
 harness = false
 
+[[bench]]
+name = "arraystring"
+harness = false
+
 [features]
 default = ["std"]
 std = []

benches/arraystring.rs

@@ -0,0 +1,90 @@
+
+extern crate arrayvec;
+#[macro_use] extern crate bencher;
+
+use arrayvec::ArrayString;
+
+use bencher::Bencher;
+
+fn try_push_c(b: &mut Bencher) {
+    let mut v = ArrayString::<[u8; 512]>::new();
+    b.iter(|| {
+        v.clear();
+        while v.try_push('c').is_ok() {
+        }
+        v.len()
+    });
+    b.bytes = v.capacity() as u64;
+}
+
+fn try_push_alpha(b: &mut Bencher) {
+    let mut v = ArrayString::<[u8; 512]>::new();
+    b.iter(|| {
+        v.clear();
+        while v.try_push('α').is_ok() {
+        }
+        v.len()
+    });
+    b.bytes = v.capacity() as u64;
+}
+
+// Yes, pushing a string char-by-char is slow. Use .push_str.
+fn try_push_string(b: &mut Bencher) {
+    let mut v = ArrayString::<[u8; 512]>::new();
+    let input = "abcαβγ“”";
+    b.iter(|| {
+        v.clear();
+        for ch in input.chars().cycle() {
+            if !v.try_push(ch).is_ok() {
+                break;
+            }
+        }
+        v.len()
+    });
+    b.bytes = v.capacity() as u64;
+}
+
+fn push_c(b: &mut Bencher) {
+    let mut v = ArrayString::<[u8; 512]>::new();
+    b.iter(|| {
+        v.clear();
+        while !v.is_full() {
+            v.push('c');
+        }
+        v.len()
+    });
+    b.bytes = v.capacity() as u64;
+}
+
+fn push_alpha(b: &mut Bencher) {
+    let mut v = ArrayString::<[u8; 512]>::new();
+    b.iter(|| {
+        v.clear();
+        while !v.is_full() {
+            v.push('α');
+        }
+        v.len()
+    });
+    b.bytes = v.capacity() as u64;
+}
+
+fn push_string(b: &mut Bencher) {
+    let mut v = ArrayString::<[u8; 512]>::new();
+    let input = "abcαβγ“”";
+    b.iter(|| {
+        v.clear();
+        for ch in input.chars().cycle() {
+            if !v.is_full() {
+                v.push(ch);
+            } else {
+                break;
+            }
+        }
+        v.len()
+    });
+    b.bytes = v.capacity() as u64;
+}
+
+benchmark_group!(benches, try_push_c, try_push_alpha, try_push_string, push_c,
+                 push_alpha, push_string);
+benchmark_main!(benches);