cmd/stbench: rm -r cmd/stbench (#6131)

This is apparently an old benchmarking tool. I'd forgotten about it.
Since 67b8ef1f3ef419c5e9d561aa6dd88e7e1eaf9901 the build script tries to
build all binaries explicitly by default, and this fails on Windows as
this tool doesn't build on Windows.

Kill it with fire.

cmd/stbench/main.go

@@ -1,143 +0,0 @@
-// Copyright (C) 2016 The Syncthing Authors.
-//
-// This Source Code Form is subject to the terms of the Mozilla Public
-// License, v. 2.0. If a copy of the MPL was not distributed with this file,
-// You can obtain one at https://mozilla.org/MPL/2.0/.
-
-// This doesn't build on Windows due to the Rusage stuff.
-
-// +build !windows
-
-package main
-
-import (
-	"flag"
-	"fmt"
-	"log"
-	"runtime"
-	"syscall"
-	"time"
-
-	"github.com/syncthing/syncthing/lib/rc"
-)
-
-var homeDir = "h1"
-var syncthingBin = "./bin/syncthing"
-var test = "scan"
-
-func main() {
-	flag.StringVar(&homeDir, "home", homeDir, "Home directory location")
-	flag.StringVar(&syncthingBin, "bin", syncthingBin, "Binary location")
-	flag.StringVar(&test, "test", test, "Test to run")
-	flag.Parse()
-
-	switch test {
-	case "scan":
-		// scan measures the resource usage required to perform the initial
-		// scan, without cleaning away the database first.
-		testScan()
-	}
-}
-
-// testScan starts a process and reports on the resource usage required to
-// perform the initial scan.
-func testScan() {
-	log.Println("Starting...")
-	p := rc.NewProcess("127.0.0.1:8081")
-	if err := p.Start(syncthingBin, "-home", homeDir, "-no-browser"); err != nil {
-		log.Println(err)
-		return
-	}
-	defer p.Stop()
-
-	wallTime := awaitScanComplete(p)
-
-	report(p, wallTime)
-}
-
-// awaitScanComplete waits for a folder to transition idle->scanning and
-// then scanning->idle and returns the time taken for the scan.
-func awaitScanComplete(p *rc.Process) time.Duration {
-	log.Println("Awaiting scan completion...")
-	var t0, t1 time.Time
-	lastEvent := 0
-loop:
-	for {
-		evs, err := p.Events(lastEvent)
-		if err != nil {
-			continue
-		}
-
-		for _, ev := range evs {
-			if ev.Type == "StateChanged" {
-				data := ev.Data.(map[string]interface{})
-				log.Println(ev)
-
-				if data["to"].(string) == "scanning" {
-					t0 = ev.Time
-					continue
-				}
-
-				if !t0.IsZero() && data["to"].(string) == "idle" {
-					t1 = ev.Time
-					break loop
-				}
-			}
-			lastEvent = ev.ID
-		}
-
-		time.Sleep(250 * time.Millisecond)
-	}
-
-	return t1.Sub(t0)
-}
-
-// report stops the given process and reports on its resource usage in two
-// ways: human readable to stderr, and CSV to stdout.
-func report(p *rc.Process, wallTime time.Duration) {
-	sv, err := p.SystemVersion()
-	if err != nil {
-		log.Println(err)
-		return
-	}
-
-	ss, err := p.SystemStatus()
-	if err != nil {
-		log.Println(err)
-		return
-	}
-
-	proc, err := p.Stop()
-	if err != nil {
-		return
-	}
-
-	rusage, ok := proc.SysUsage().(*syscall.Rusage)
-	if !ok {
-		return
-	}
-
-	log.Println("Version:", sv.Version)
-	log.Println("Alloc:", ss.Alloc/1024, "KiB")
-	log.Println("Sys:", ss.Sys/1024, "KiB")
-	log.Println("Goroutines:", ss.Goroutines)
-	log.Println("Wall time:", wallTime)
-	log.Println("Utime:", time.Duration(rusage.Utime.Nano()))
-	log.Println("Stime:", time.Duration(rusage.Stime.Nano()))
-	if runtime.GOOS == "darwin" {
-		// Darwin reports in bytes, Linux seems to report in KiB even
-		// though the manpage says otherwise.
-		rusage.Maxrss /= 1024
-	}
-	log.Println("MaxRSS:", rusage.Maxrss, "KiB")
-
-	fmt.Printf("%s,%d,%d,%d,%.02f,%.02f,%.02f,%d\n",
-		sv.Version,
-		ss.Alloc/1024,
-		ss.Sys/1024,
-		ss.Goroutines,
-		wallTime.Seconds(),
-		time.Duration(rusage.Utime.Nano()).Seconds(),
-		time.Duration(rusage.Stime.Nano()).Seconds(),
-		rusage.Maxrss)
-}