Convert to Go

sample/.gitignore

@@ -0,0 +1 @@
+sample

sample/main.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"math/rand"
+	"os"
+	"strconv"
+	"time"
+)
+
+func main() {
+	var total int64
+	var emitted int64
+	if len(os.Args) != 2 {
+		fmt.Fprintf(os.Stderr, "invalid argument. use a fraction to sample between 0.0 (no sampling) and 1.0 (100% sampling)")
+		os.Exit(1)
+	}
+
+	target, err := strconv.ParseFloat(os.Args[1], 64)
+	if err != nil || target < 0.0 || target > 1.0 {
+		fmt.Fprintf(os.Stderr, "Unable to convert %q to a float between 0.0 and 1.0", os.Args[1])
+		os.Exit(1)
+	}
+
+	out := bufio.NewWriterSize(os.Stdout, 1024*512)
+
+	rand.Seed(time.Now().UnixNano())
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		total += 1
+		if target < rand.Float64() {
+			continue
+		}
+		emitted += 1
+		out.WriteString(scanner.Text())
+		out.WriteString("\n")
+	}
+	if err := scanner.Err(); err != nil {
+		fmt.Fprintln(os.Stderr, "Error reading standard input:", err)
+		os.Exit(2)
+	}
+	out.Flush()
+	fmt.Fprintf(os.Stderr, "Total of %d lines. Sampled to %d\n", total, emitted)
+}