Add some tools for analysing bloom filter use

internal/cmd/bloom-estimate/main.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"github.com/willf/bloom"
+)
+
+func main() {
+	n := flag.Int("n", 0, "expected number of items")
+	falsePositiveRate := flag.Float64("fpr", 0, "false positive rate")
+	flag.Parse()
+	filter := bloom.NewWithEstimates(uint(*n), *falsePositiveRate)
+	fmt.Printf("m: %d, k: %d\n", filter.Cap(), filter.K())
+}

internal/cmd/bloom-false-positives/main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"bufio"
+	"flag"
+	"fmt"
+	"github.com/willf/bloom"
+	"os"
+)
+
+func main() {
+	m := flag.Uint("m", 0, "")
+	k := flag.Uint("k", 0, "")
+	flag.Parse()
+	filter := bloom.New(*m, *k)
+	scanner := bufio.NewScanner(os.Stdin)
+	n := 0
+	collisions := 0
+	for scanner.Scan() {
+		if filter.TestAndAdd(scanner.Bytes()) {
+			collisions++
+		}
+		n++
+	}
+	if err := scanner.Err(); err != nil {
+		fmt.Fprintf(os.Stderr, "error reading stdin: %s", err)
+		os.Exit(1)
+	}
+	fmt.Printf("collisions %d/%d (%f)\n", collisions, n, float64(collisions)/float64(n)*100)
+}