String Search Benchmarks as discussed https://stackoverflow.com/questions/51611862/go-strings-contains-2x-slower-than-python3

string_search_benchmarks.go

package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"strings"
	"testing"
	"time"

	"github.com/cloudflare/ahocorasick"
	"github.com/cubicdaiya/bms"
	yara "github.com/hillu/go-yara"
	"github.com/kkdai/kmp"
	"github.com/paddie/gokmp"
)

const (
	runs = 10000
)

// This is https://raw.githubusercontent.com/gwillem/magento-malware-scanner/master/corpus/backend/3f34f51c981a9ddcfb0f41815c7dad49
var haystack = readFile("data.php")

// Random needle, doesn't exist in my haystack which is the most common case
var needle = "576ad4f370014dfb1d0f17b0e6855f22"

var yararules = getYaraRules()

func BenchmarkStringsContains(b *testing.B) {
	for i := 0; i < b.N; i++ {
		_ = strings.Contains(haystack, needle)
	}
}

func BenchmarkBMSSearch(b *testing.B) {
	for i := 0; i < b.N; i++ {
		_ = bms.Search(haystack, needle)
	}
}

func BenchmarkPaddieKMP(b *testing.B) {
	kmp, _ := gokmp.NewKMP(needle)
	for i := 0; i < b.N; i++ {
		_ = kmp.FindStringIndex(haystack)
	}
}

func BenchmarkKkdaiKMP(b *testing.B) {
	for i := 0; i < b.N; i++ {
		// _ = kmp.KMP(haystack, needle) // 1.46 ms
		// _ = kmp.Strstr(haystack, needle) // 1.64 ms
		_ = kmp.Strchr(haystack, needle) // 1.44 ms
	}
}
func BenchmarkAhocorasick(b *testing.B) {
	patterns := []string{needle}
	testbytes := []byte(haystack)
	m := ahocorasick.NewStringMatcher(patterns)

	for i := 0; i < b.N; i++ {
		_ = m.Match(testbytes)
	}
}

func getYaraRules() *yara.Rules {
	yc, _ := yara.NewCompiler()
	namespace := "test"
	yararule := `rule goyara_test {
        strings: $ = "%s"
        condition: any of them
}
`
	yararule = fmt.Sprintf(yararule, needle)
	yc.AddString(yararule, namespace)
	rules, _ := yc.GetRules()
	return rules
}
func BenchmarkYara(b *testing.B) {
	testbytes := []byte(haystack)
	timeout := 10 * time.Second
	for i := 0; i < b.N; i++ {
		yararules.ScanMem(testbytes, yara.ScanFlagsFastMode, timeout)
	}

}
func readFile(fname string) string {
	data, err := ioutil.ReadFile(fname)
	if err != nil {
		log.Fatal(err)
	}
	return string(data)
}