Add a rough benchmark for shell.Split.

1 files changed, 74 insertions, 0 deletions

diff --git a/bench_test.go b/bench_test.go
new file mode 100644
index 0000000..23c86a8
--- /dev/null
+++ b/bench_test.go
@@ -0,0 +1,74 @@
+package shell_test
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+	"math/rand"
+	"testing"
+
+	"bitbucket.org/creachadair/shell"
+)
+
+var input string
+
+// Generate a long random string with balanced quotations for perf testing.
+func init() {
+	var buf bytes.Buffer
+
+	src := rand.NewSource(12345)
+	r := rand.New(src)
+
+	const alphabet = "abcdefghijklmnopqrstuvwxyz0123456789   \t\n\n\n"
+	pick := func(f float64) byte {
+		pos := math.Ceil(f*float64(len(alphabet))) - 1
+		return alphabet[int(pos)]
+	}
+
+	const inputLen = 100000
+	var quote struct {
+		q byte
+		n int
+	}
+	for i := 0; i < inputLen; i++ {
+		if quote.n == 0 {
+			q := r.Float64()
+			if q < .1 {
+				quote.q = '"'
+				quote.n = r.Intn(256)
+				buf.WriteByte('"')
+				continue
+			} else if q < .15 {
+				quote.q = '\''
+				quote.n = r.Intn(256)
+				buf.WriteByte('\'')
+				continue
+			}
+		}
+		buf.WriteByte(pick(r.Float64()))
+		if quote.n > 0 {
+			quote.n--
+			if quote.n == 0 {
+				buf.WriteByte(quote.q)
+			}
+		}
+	}
+	input = buf.String()
+}
+
+func BenchmarkSplit(b *testing.B) {
+	var lens []int
+	for i := 1; i < len(input); i *= 4 {
+		lens = append(lens, i)
+	}
+	lens = append(lens, len(input))
+
+	b.ResetTimer()
+	for _, n := range lens {
+		b.Run(fmt.Sprintf("len_%d", n), func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				shell.Split(input[:n])
+			}
+		})
+	}
+}