bent.go

// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bufio"
	"bytes"
	"flag"
	"fmt"
	"github.com/BurntSushi/toml"
	"io"
	"io/ioutil"
	"math/rand"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"
)

type BenchStat struct {
	Name                        string
	RealTime, UserTime, SysTime int64 // nanoseconds, -1 if missing.
}

type Configuration struct {
	Name        string   // Short name used for binary names, mention on command line
	Root        string   // Specific Go root to use for this trial
	BuildFlags  []string // BuildFlags supplied to 'go test -c' for building (e.g., "-p 1")
	AfterBuild  []string // Array of commands to run, output of all commands for a configuration (across binaries) is collected in <runstamp>.<config>.<cmd>
	GcFlags     string   // GcFlags supplied to 'go test -c' for building
	GcEnv       []string // Environment variables supplied to 'go test -c' for building
	RunFlags    []string // Extra flags passed to the test binary
	RunEnv      []string // Extra environment variables passed to the test binary
	RunWrapper  []string // (Outermost) Command and args to precede whatever the operation is; may fail in the sandbox.
	Disabled    bool     // True if this configuration is temporarily disabled
	buildStats  []BenchStat
	benchWriter *os.File
	rootCopy    string // The contents of GOROOT are copied here to allow benchmarking of just the test compilation.
}

type Benchmark struct {
	Name       string   // Short name for benchmark/test
	Contact    string   // Contact not used, but may be present in description
	Repo       string   // Repo + subdir where test resides, used for "go get -t -d ..."
	Tests      string   // Tests to run (regex for -test.run= )
	Benchmarks string   // Benchmarks to run (regex for -test.bench= )
	GcEnv      []string // Environment variables supplied to 'go test -c' for building, getting
	BuildFlags []string // Flags for building test (e.g., -tags purego)
	RunWrapper []string // (Inner) Command and args to precede whatever the operation is; may fail in the sandbox.
	// e.g. benchmark may run as ConfigWrapper ConfigArg BenchWrapper BenchArg ActualBenchmark
	NotSandboxed bool // True if this benchmark cannot or should not be run in a container.
	Disabled     bool // True if this benchmark is temporarily disabled.
}

type Todo struct {
	Benchmarks     []Benchmark
	Configurations []Configuration
}

// The length of the path to the root of the git repo, inclusive.
// For example, github.com/dr2chase/bent <--- bent is the repo.
var pathLengths = map[string]int{
	"github.com":    3,
	"gitlab.com":    3,
	"zombiezen.com": 3,
	"gonum.org":     3,
	"k8s.io":        2,
	"go.uber.org":   2,
}

var verbose int

var benchFile = "benchmarks-50.toml"         // default list of benchmarks
var confFile = "configurations.toml"         // default list of configurations
var testBinDir = "testbin"                   // destination for generated binaries
var benchDir = "bench"                       // destination for benchmark outputs
var srcPath = "src/github.com/dr2chase/bent" // Used to find configuration files.
var container = ""
var N = 1
var list = false
var initialize = false
var test = false
var force = false
var noSandbox = false
var requireSandbox = false
var getOnly = false
var runContainer = "" // if nonempty, skip builds and use existing named container (or binaries if -U )
var wikiTable = false // emit the tests in a form usable in a wiki table
var explicitAll = 0   // Include "-a" on "go test -c" test build ; repeating flag causes multiple rebuilds, useful for build benchmarking.
var shuffle = 2       // Dimensionality of (build) shuffling; 0 = none, 1 = per-benchmark, configuration ordering, 2 = bench, config pairs, 3 = across repetitions.

var copyExes = []string{
	"foo", "memprofile", "cpuprofile", "tmpclr", "benchtime", "benchsize", "benchdwarf", "cronjob.sh", "cmpjob.sh", "cmpcl.sh", "cmpcl-phase.sh", "tweet-results",
}

var copyConfigs = []string{
	"benchmarks-all.toml", "benchmarks-50.toml", "benchmarks-gc.toml", "benchmarks-gcplus.toml", "benchmarks-trial.toml",
	"configurations-sample.toml", "configurations-gollvm.toml", "configurations-cronjob.toml", "configurations-cmpjob.toml",
}

var defaultEnv []string

type pair struct {
	b, c int
}
type triple struct {
	b, c, k int
}

// To disambiguate repeated test runs in the same directory.
var runstamp = strings.Replace(strings.Replace(time.Now().Format("2006-01-02T15:04:05"), "-", "", -1), ":", "", -1)

func cleanup(gopath string) {
	if verbose > 0 {
		fmt.Printf("chmod -R u+w %s\n", gopath+"/pkg")
	}
	// Necessary to make directories writeable with new module stuff.
	filepath.Walk(gopath+"/pkg", func(path string, info os.FileInfo, err error) error {
		if path != "" && info != nil {
			if mode := info.Mode(); 0 == mode&os.ModeSymlink {
				err := os.Chmod(path, 0200|mode)
				if err != nil {
					panic(err)
				}
			}
		}
		return nil
	})
	if verbose > 0 {
		fmt.Printf("rm -rf %s %s\n", gopath+"/pkg", gopath+"/bin")
	}
	os.RemoveAll(gopath + "/pkg")
	os.RemoveAll(gopath + "/bin")
}

func main() {

	var benchmarksString, configurationsString, stampLog string

	flag.IntVar(&N, "N", N, "benchmark/test repeat count")

	flag.Var((*count)(&explicitAll), "a", "add '-a' flag to 'go test -c' to demand full recompile. Repeat or assign a value for repeat builds for benchmarking")
	flag.IntVar(&shuffle, "s", shuffle, "dimensionality of (build) shuffling (0-3), 0 = none, 1 = per-benchmark, configuration ordering, 2 = bench, config pairs, 3 = across repetitions.")

	flag.StringVar(&benchmarksString, "b", "", "comma-separated list of test/benchmark names (default is all)")
	flag.StringVar(&benchFile, "B", benchFile, "name of file describing benchmarks")

	flag.StringVar(&configurationsString, "c", "", "comma-separated list of test/benchmark configurations (default is all)")
	flag.StringVar(&confFile, "C", confFile, "name of file describing configurations")

	flag.BoolVar(&noSandbox, "U", noSandbox, "run all commands unsandboxed")
	flag.BoolVar(&requireSandbox, "S", requireSandbox, "exclude unsandboxable tests/benchmarks")

	flag.BoolVar(&getOnly, "g", getOnly, "get tests/benchmarks and dependencies, do not build or run")
	flag.StringVar(&runContainer, "r", runContainer, "skip get and build, go directly to run, using specified container (any non-empty string will do for unsandboxed execution)")

	flag.StringVar(&stampLog, "L", stampLog, "name of log file to which runstamps are appended")

	flag.BoolVar(&list, "l", list, "list available benchmarks and configurations, then exit")
	flag.BoolVar(&force, "f", force, "force run past some of the consistency checks (gopath/{pkg,bin} in particular)")
	flag.BoolVar(&initialize, "I", initialize, "initialize a directory for running tests ((re)creates Dockerfile, (re)copies in benchmark and configuration files)")
	flag.BoolVar(&test, "T", test, "run tests instead of benchmarks")

	flag.BoolVar(&wikiTable, "W", wikiTable, "print benchmark info for a wiki table")

	flag.Var((*count)(&verbose), "v", "print commands and other information (more -v = print more details)")

	flag.Usage = func() {
		fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
		flag.PrintDefaults()
		fmt.Fprintf(os.Stderr,
			`
%s obtains the benchmarks/tests listed in %s and compiles 
and runs them according to the flags and environment 
variables supplied in %s. Specifying "-a" will pass "-a" to
test compilations, but normally this should not be needed
and only slows down builds; -a with a number that is not 1
can be used for benchmarking builds of the tests themselves.
(Don't forget to specify "all=..." for GCFLAGS if you want
those applied to the entire build.)

Both of these files can be changed with the -B and -C flags; the full
suite of benchmarks in benchmarks-all.toml is somewhat time-consuming.

Running with the -l flag will list all the available tests and benchmarks
for the given benchmark and configuration files.

By default the compiled tests are run in a docker container to reduce
the chances for accidents and mischief. -U requests running tests
unsandboxed, and -S limits the tests run to those that can be sandboxed
(some cannot be because of cross-compilation issues; this may imply no
change on platforms where the Docker container is not cross-compiled)

By default benchmarks are run, not tests.  -T runs tests instead

This command expects to be run in a directory that does not contain
subdirectories "gopath/pkg" and "gopath/bin", because those subdirectories 
may be created (and deleted) in the process of compiling the benchmarks.
The same is true of subdirectory "goroots".
It will also extensively modify subdirectory "gopath/src".

All the test binaries will appear in the subdirectory 'testbin',
and test (benchmark) output will appear in the subdirectory 'bench'
with the suffix '.stdout'.  The test output is grouped by configuration
to allow easy benchmark comparisons with benchstat.  Other benchmarking
results will also appear in 'bench'.
`, os.Args[0], benchFile, confFile)
	}

	flag.Parse()

	cwd, err := os.Getwd()
	if err != nil {
		fmt.Printf("Could not get current working directory\n", err)
		os.Exit(1)
		return
	}
	gopath := cwd + "/gopath"
	err = os.Mkdir(gopath, 0775)

	// To avoid bad surprises, look for pkg and bin, if they exist, refuse to run
	_, derr := os.Stat("Dockerfile")
	_, perr := os.Stat("gopath/pkg")
	_, berr := os.Stat("gopath/bin")
	_, serr := os.Stat("gopath/src") // existence of src prevents initialization of Dockerfile

	if perr == nil || berr == nil {
		if !force {
			fmt.Printf("Building/running tests will trash gopath/pkg and gopath/bin, please remove, rename or run in another directory, or use -f to force.\n")
			os.Exit(1)
		}
		fmt.Printf("Building/running tests will trash gopath/pkg and gopath/bin, but force, so removing.\n")
		cleanup("gopath")
	}
	if derr != nil && !initialize {
		// Missing Dockerfile
		fmt.Printf("Missing 'Dockerfile', please rerun with -I (initialize) flag if you intend to use this directory.\n")
		os.Exit(1)
	}

	if shuffle < 0 || shuffle > 3 {
		fmt.Printf("Shuffle value (-s) ought to be between 0 and 3, inclusive, instead is %d\n", shuffle)
		os.Exit(1)
	}

	// Create directory that will contain GOROOT for each configuration.
	goroots := cwd + "/goroots"
	err = os.Mkdir(goroots, 0775)

	// Initialize the directory, copying in default benchmarks and sample configurations, and creating a Dockerfile
	if initialize {
		anyerr := false
		if serr == nil {
			fmt.Printf("It looks like you've already initialized this directory, remove ./gopath if you want to reinit.\n")
			anyerr = true
		}
		if anyerr {
			os.Exit(1)
		}
		for _, s := range copyExes {
			copyAsset(s)
			os.Chmod(s, 0755)
		}
		for _, s := range copyConfigs {
			copyAsset(s)
		}

		err := ioutil.WriteFile("Dockerfile",
			[]byte(`
FROM ubuntu
ADD . /
`), 0664)
		if err != nil {
			fmt.Printf("There was an error creating %s: %v\n", "Dockerfile", err)
			os.Exit(1)
			return
		}
		fmt.Printf("Created Dockerfile\n")
		return
	}

	todo := &Todo{}
	blobB, err := ioutil.ReadFile(benchFile)
	if err != nil {
		fmt.Printf("There was an error opening or reading file %s: %v\n", benchFile, err)
		os.Exit(1)
		return
	}
	blobC, err := ioutil.ReadFile(confFile)
	if err != nil {
		fmt.Printf("There was an error opening or reading file %s: %v\n", confFile, err)
		os.Exit(1)
		return
	}
	blob := append(blobB, blobC...)
	err = toml.Unmarshal(blob, todo)
	if err != nil {
		fmt.Printf("There was an error unmarshalling %s: %v\n", string(blob), err)
		os.Exit(1)
		return
	}

	var moreArgs []string
	if flag.NArg() > 0 {
		for i, arg := range flag.Args() {
			if i == 0 && (arg == "-" || arg == "--") {
				continue
			}
			moreArgs = append(moreArgs, arg)
		}
	}

	benchmarks := csToSet(benchmarksString)
	configurations := csToSet(configurationsString)

	if wikiTable {
		for _, bench := range todo.Benchmarks {
			s := bench.Benchmarks
			s = strings.Replace(s, "|", "\\|", -1)
			fmt.Printf(" | %s | | `%s` | `%s` | |\n", bench.Name, bench.Repo, s)
		}
		return
	}

	// Normalize configuration goroot names by ensuring they end in '/'
	// Process command-line-specified configurations.
	// Expand environment variables mentioned there.
	duplicates := make(map[string]bool)
	for i, trial := range todo.Configurations {
		trial.Name = os.ExpandEnv(trial.Name)
		todo.Configurations[i].Name = trial.Name
		if duplicates[trial.Name] {
			if trial.Name == todo.Configurations[i].Name {
				fmt.Printf("Saw duplicate configuration %s at index %d\n", trial.Name, i)
			} else {
				fmt.Printf("Saw duplicate configuration %s (originally %s) at index %d\n", trial.Name, todo.Configurations[i].Name, i)
			}
			os.Exit(1)
		}
		duplicates[trial.Name] = true
		if configurations != nil {
			_, present := configurations[trial.Name]
			todo.Configurations[i].Disabled = !present
			if present {
				configurations[trial.Name] = false
			}
		}
		root := trial.Root
		if root != "" {
			root = os.ExpandEnv(root)
			if '/' != root[len(root)-1] {
				root = root + "/"
			}
			todo.Configurations[i].Root = root
		}
		for j, s := range trial.GcEnv {
			trial.GcEnv[j] = os.ExpandEnv(s)
		}
		for j, s := range trial.RunEnv {
			trial.RunEnv[j] = os.ExpandEnv(s)
		}
		todo.Configurations[i].GcFlags = os.ExpandEnv(trial.GcFlags)
		for j, s := range trial.RunFlags {
			trial.RunFlags[j] = os.ExpandEnv(s)
		}
		for j, s := range trial.RunWrapper {
			trial.RunWrapper[j] = os.ExpandEnv(s)
		}
	}
	for b, v := range configurations {
		if v {
			fmt.Printf("Configuration %s listed after -c does not appear in %s\n", b, confFile)
			os.Exit(1)
		}
	}

	// Normalize benchmark names by removing any trailing '/'.
	// Normalize Test and Benchmark specs by replacing missing value with something that won't match anything.
	// Process command-line-specified benchmarks
	duplicates = make(map[string]bool)
	for i, bench := range todo.Benchmarks {

		if duplicates[bench.Name] {
			fmt.Printf("Saw duplicate benchmark %s at index %d\n", bench.Name, i)
			os.Exit(1)
		}
		duplicates[bench.Name] = true

		if benchmarks != nil {
			_, present := benchmarks[bench.Name]
			todo.Benchmarks[i].Disabled = !present
			if present {
				benchmarks[bench.Name] = false
			}
		}
		for j, s := range bench.GcEnv {
			bench.GcEnv[j] = os.ExpandEnv(s)
		}
		// Trim possible trailing slash, do not want
		if '/' == bench.Repo[len(bench.Repo)-1] {
			bench.Repo = bench.Repo[:len(bench.Repo)-1]
			todo.Benchmarks[i].Repo = bench.Repo
		}
		if "" == bench.Tests || !test {
			if !test {
				todo.Benchmarks[i].Tests = "none"
			} else {
				todo.Benchmarks[i].Tests = "Test"
			}
		}
		if "" == bench.Benchmarks || test {
			if !test {
				todo.Benchmarks[i].Benchmarks = "Benchmark"
			} else {
				todo.Benchmarks[i].Benchmarks = "none"
			}
		}
		if noSandbox {
			todo.Benchmarks[i].NotSandboxed = true
		}
		if requireSandbox && todo.Benchmarks[i].NotSandboxed {
			if runtime.GOOS == "linux" {
				fmt.Printf("Removing sandbox for %s\n", bench.Name)
				todo.Benchmarks[i].NotSandboxed = false
			} else {
				fmt.Printf("Disabling %s because it requires sandbox\n", bench.Name)
				todo.Benchmarks[i].Disabled = true
			}
		}
	}
	for b, v := range benchmarks {
		if v {
			fmt.Printf("Benchmark %s listed after -b does not appear in %s\n", b, benchFile)
			os.Exit(1)
		}
	}

	// If more verbose, print the normalized configuration.
	if verbose > 1 {
		buf := new(bytes.Buffer)
		if err := toml.NewEncoder(buf).Encode(todo); err != nil {
			fmt.Printf("There was an error encoding %v: %v\n", todo, err)
			os.Exit(1)
		}
		fmt.Println(buf.String())
	}

	if list {
		fmt.Println("Benchmarks:")
		for _, x := range todo.Benchmarks {
			s := x.Name + " (repo=" + x.Repo + ")"
			if x.Disabled {
				s += " (disabled)"
			}
			fmt.Printf("   %s\n", s)
		}
		fmt.Println("Configurations:")
		for _, x := range todo.Configurations {
			s := x.Name
			if x.Root != "" {
				s += " (goroot=" + x.Root + ")"
			}
			if x.Disabled {
				s += " (disabled)"
			}
			fmt.Printf("   %s\n", s)
		}
		return
	}

	if stampLog != "" {
		f, err := os.OpenFile(stampLog, os.O_WRONLY|os.O_APPEND|os.O_CREATE, os.ModePerm)
		if err != nil {
			fmt.Printf("There was an error opening %s for output, error %v\n", stampLog, err)
			os.Exit(2)
		}
		fmt.Fprintf(f, "%s\t%v\n", runstamp, os.Args)
		f.Close()
	}

	defaultEnv = inheritEnv(defaultEnv, "PATH")
	defaultEnv = inheritEnv(defaultEnv, "USER")
	defaultEnv = inheritEnv(defaultEnv, "HOME")
	defaultEnv = inheritEnv(defaultEnv, "SHELL")
	for _, e := range os.Environ() {
		if strings.HasPrefix(e, "GO") {
			defaultEnv = append(defaultEnv, e)
		}
	}
	defaultEnv = replaceEnv(defaultEnv, "GOPATH", gopath)
	defaultEnv = replaceEnv(defaultEnv, "GOOS", runtime.GOOS)
	defaultEnv = replaceEnv(defaultEnv, "GOARCH", runtime.GOARCH)
	defaultEnv = ifMissingAddEnv(defaultEnv, "GO111MODULE", "auto")

	var needSandbox bool    // true if any benchmark needs a sandbox
	var needNotSandbox bool // true if any benchmark needs to be not sandboxed

	var getAndBuildFailures []string

	err = os.Mkdir(testBinDir, 0775)
	err = os.Mkdir(benchDir, 0775)
	// Ignore the error -- TODO note the difference between exists already and other errors.

	for i, config := range todo.Configurations {
		if !config.Disabled { // Don't overwrite if something was disabled.
			s := config.thingBenchName("stdout")
			f, err := os.OpenFile(s, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, os.ModePerm)
			if err != nil {
				fmt.Printf("There was an error opening %s for output, error %v\n", s, err)
				os.Exit(2)
			}
			todo.Configurations[i].benchWriter = f
		}
	}

	// It is possible to request repeated builds for compiler/linker benchmarking.
	// Normal (non-negative build count) varies configuration most frequently,
	// then benchmark, then repeats the process N times (innerBuildCount = 1).
	// If build count is negative, the configuration varies least frequently,
	// and each benchmark is built buildCount (innerBuildCount) times before
	// moving on to the next. (This tends to focus intermittent benchmarking
	// noise on single confioguration-benchmark combos.  This is the "old way".
	buildCount := explicitAll
	if buildCount < 0 {
		buildCount = -buildCount
	}
	if buildCount == 0 {
		buildCount = 1
	}

	if runContainer == "" { // If not reusing binaries/container...
		if verbose == 0 {
			fmt.Print("Go getting")
		}

		// Obtain (go get -d -t -v bench.Repo) all benchmarks, once, populating src
		for i, bench := range todo.Benchmarks {
			if bench.Disabled {
				continue
			}
			getBuildEnv := replaceEnvs(defaultEnv, bench.GcEnv)

			cmd := exec.Command("go", "get", "-d", "-t", "-v", bench.Repo)
			cmd.Env = getBuildEnv

			if !bench.NotSandboxed { // Do this so that OS-dependent dependencies are done correctly.
				cmd.Env = replaceEnv(cmd.Env, "GOOS", "linux")
			}
			if verbose > 0 {
				fmt.Println(asCommandLine(cwd, cmd))
			} else {
				fmt.Print(".")
			}
			_, err := cmd.Output()
			if err != nil {
				ee := err.(*exec.ExitError)
				s := fmt.Sprintf("There was an error running 'go get', stderr = %s", ee.Stderr)
				fmt.Println(s + "DISABLING benchmark " + bench.Name)
				getAndBuildFailures = append(getAndBuildFailures, s+"("+bench.Name+")\n")
				todo.Benchmarks[i].Disabled = true
				continue
			}

			// Ensure testdir exists -- if modules are enabled, it does not.
			// This involves invoking git to make it appear.
			testdir := gopath + "/src/" + bench.Repo
			_, terr := os.Stat(testdir)
			if terr != nil { // Assume missing directory is the cause of the error.
				parts := strings.Split(bench.Repo, "/")
				root := parts[0]
				repoAt := pathLengths[root] - 1
				if repoAt < 1 || repoAt >= len(parts) {
					s := fmt.Sprintf("repoAt=%d was not a valid index for %v", repoAt, parts)
					fmt.Println(s + "DISABLING benchmark " + bench.Name)
					getAndBuildFailures = append(getAndBuildFailures, s+"("+bench.Name+")\n")
					todo.Benchmarks[i].Disabled = true
					continue
				}
				dirToMake := gopath + "/src/" + strings.Join(parts[:repoAt], "/")
				repoToGet := strings.Join(parts[:repoAt+1], "/")
				if verbose > 0 {
					fmt.Printf("mkdir -p %s\n", dirToMake)
				}
				err := os.MkdirAll(dirToMake, 0777)
				if err != nil {
					s := fmt.Sprintf("could not os.MkdirAll(%s), err = %v", dirToMake, err)
					fmt.Println(s + "DISABLING benchmark " + bench.Name)
					getAndBuildFailures = append(getAndBuildFailures, s+"("+bench.Name+")\n")
					todo.Benchmarks[i].Disabled = true
					continue
				}

				cmd = exec.Command("git", "clone", "https://"+repoToGet)
				cmd.Env = defaultEnv
				cmd.Dir = dirToMake
				if verbose > 0 {
					fmt.Println(asCommandLine(cwd, cmd))
				} else {
					fmt.Print(".")
				}
				_, err = cmd.Output()
				if err != nil {
					ee := err.(*exec.ExitError)
					s := fmt.Sprintf("There was an error running 'git clone', stderr = %s", ee.Stderr)
					fmt.Println(s + "DISABLING benchmark " + bench.Name)
					getAndBuildFailures = append(getAndBuildFailures, s+"("+bench.Name+")\n")
					todo.Benchmarks[i].Disabled = true
					continue
				}
				// This next bit often doesn't work, because reasons.
				// There is probably an algorithm for the right place to run go mod init/tidy,
				// but I don't know it and the two simple ones I tried didn't work.

				// repoDir :=  gopath + "/src/" + strings.Join(parts[:repoAt+1],"/")

				// // Try a go mod init.
				// cmd = exec.Command("go", "mod", "init")
				// cmd.Env = getBuildEnv
				// cmd.Dir = repoDir
				// if verbose > 0 {
				// 	fmt.Println(asCommandLine(cwd, cmd))
				// } else {
				// 	fmt.Print(".")
				// }
				// _, err = cmd.Output()
				// if err != nil {
				// 	ee := err.(*exec.ExitError)
				// 	fmt.Printf("go mod init returned %s but that is normal if go.mod already exists\n", ee.Stderr)
				// } else {
				// 	// Try a go mod tidy.
				// 	cmd = exec.Command("go", "mod", "tidy")
				// 	cmd.Env = getBuildEnv
				// 	cmd.Dir = repoDir
				// 	if verbose > 0 {
				// 		fmt.Println(asCommandLine(cwd, cmd))
				// 	} else {
				// 		fmt.Print(".")
				// 	}
				// 	_, err = cmd.Output()
				// 	if err != nil {
				// 		ee := err.(*exec.ExitError)
				// 		s := fmt.Sprintf("There was an error running 'git clone', stderr = %s", ee.Stderr)
				// 		fmt.Println(s + "DISABLING benchmark " + bench.Name)
				// 		getAndBuildFailures = append(getAndBuildFailures, s+"("+bench.Name+")\n")
				// 		todo.Benchmarks[i].Disabled = true
				// 		continue
				// 	}
				// }
			}

			needSandbox = !bench.NotSandboxed || needSandbox
			needNotSandbox = bench.NotSandboxed || needNotSandbox
		}
		if verbose == 0 {
			fmt.Println()
		}

		if getOnly {
			return
		}

		// Create build-related benchmark files
		for ci := range todo.Configurations {
			todo.Configurations[ci].createFilesForLater()
		}

		// Compile tests and move to ./testbin/Bench_Config.
		// If any test needs sandboxing, then one docker container will be created
		// (that contains all the tests).

		if verbose == 0 {
			fmt.Print("Building goroots")
		}

		// First for each configuration, get the compiler and library and install it in its own GOROOT.
		for ci, config := range todo.Configurations {
			if config.Disabled {
				continue
			}

			root := config.Root

			rootCopy := goroots + "/" + config.Name + "/"
			if verbose > 0 {
				fmt.Printf("rm -rf %s\n", rootCopy)
			}
			os.RemoveAll(rootCopy)
			config.rootCopy = rootCopy
			todo.Configurations[ci] = config

			docopy := func(from, to string) {
				mkdir := exec.Command("mkdir", "-p", to)
				s, _ := config.runBinary("", mkdir, false)
				if s != "" {
					fmt.Println("Error creating directory, ", to)
					config.Disabled = true
				}

				cp := exec.Command("rsync", "-a", from+"/", to)
				s, _ = config.runBinary("", cp, false)
				if s != "" {
					fmt.Println("Error copying directory tree, ", from, to)
					// Not disabling because gollvm uses a different directory structure
				}
			}

			docopy(root+"bin", rootCopy+"bin")
			docopy(root+"src", rootCopy+"src")
			docopy(root+"pkg", rootCopy+"pkg")
			// docopy(root +"vendor", rootCopy + "vendor")

			gocmd := config.goCommandCopy()

			buildLibrary := func(withAltOS bool) {
				if withAltOS && runtime.GOOS == "linux" {
					return // The alternate OS is linux
				}
				cmd := exec.Command(gocmd, "install", "-a")
				cmd.Args = append(cmd.Args, config.BuildFlags...)
				if config.GcFlags != "" {
					cmd.Args = append(cmd.Args, "-gcflags="+config.GcFlags)
				}
				cmd.Args = append(cmd.Args, "std")
				cmd.Env = defaultEnv
				if withAltOS {
					cmd.Env = replaceEnv(cmd.Env, "GOOS", "linux")
				}
				if rootCopy != "" {
					cmd.Env = replaceEnv(cmd.Env, "GOROOT", rootCopy)
				}
				cmd.Env = replaceEnvs(cmd.Env, config.GcEnv)

				s, _ := config.runBinary("", cmd, true)
				if s != "" {
					fmt.Println("Error running go install std, ", s)
					config.Disabled = true
				}
			}

			// Prebuild the library for this configuration unless -a=1
			if explicitAll != 1 {
				if needSandbox {
					buildLibrary(true)
				}
				if needNotSandbox {
					buildLibrary(false)
				}
			}
			todo.Configurations[ci] = config
			if config.Disabled {
				continue
			}
		}

		if verbose == 0 {
			fmt.Print("\nCompiling")
		}

		switch shuffle {
		case 0: // N times, for each benchmark, for each configuration, build.
			for yyy := 0; yyy < buildCount; yyy++ {
				for bi, bench := range todo.Benchmarks {
					if bench.Disabled {
						continue
					}
					for ci, config := range todo.Configurations {
						if config.Disabled {
							continue
						}
						s := todo.Configurations[ci].compileOne(&todo.Benchmarks[bi], cwd, yyy)
						if s != "" {
							getAndBuildFailures = append(getAndBuildFailures, s)
						}
					}
				}
			}
		case 1: // N times, for each benchmark, shuffle configurations and build with
			permute := make([]int, len(todo.Configurations))
			for ci, _ := range todo.Configurations {
				permute[ci] = ci
			}

			for yyy := 0; yyy < buildCount; yyy++ {
				for bi, bench := range todo.Benchmarks {
					if bench.Disabled {
						continue
					}

					rand.Shuffle(len(permute), func(i, j int) { permute[i], permute[j] = permute[j], permute[i] })

					for ci := range todo.Configurations {
						config := &todo.Configurations[permute[ci]]
						if config.Disabled {
							continue
						}
						s := config.compileOne(&todo.Benchmarks[bi], cwd, yyy)
						if s != "" {
							getAndBuildFailures = append(getAndBuildFailures, s)
						}
					}
				}
			}
		case 2: // N times, shuffle combination of benchmarks and configuration, build them all
			permute := make([]pair, len(todo.Configurations)*len(todo.Benchmarks))
			i := 0
			for bi := range todo.Benchmarks {
				for ci := range todo.Configurations {
					permute[i] = pair{b: bi, c: ci}
					i++
				}
			}

			for yyy := 0; yyy < buildCount; yyy++ {
				rand.Shuffle(len(permute), func(i, j int) { permute[i], permute[j] = permute[j], permute[i] })
				for _, p := range permute {
					bench := &todo.Benchmarks[p.b]
					config := &todo.Configurations[p.c]
					if bench.Disabled || config.Disabled {
						continue
					}
					s := config.compileOne(bench, cwd, yyy)
					if s != "" {
						getAndBuildFailures = append(getAndBuildFailures, s)
					}
				}
			}

		case 3: // Shuffle all the N copies of all the benchmark and configuration pairs, build them all.
			permute := make([]triple, buildCount*len(todo.Configurations)*len(todo.Benchmarks))
			i := 0
			for k := 0; k < buildCount; k++ {
				for bi := range todo.Benchmarks {
					for ci := range todo.Configurations {
						permute[i] = triple{b: bi, c: ci, k: k}
						i++
					}
				}
			}
			rand.Shuffle(len(permute), func(i, j int) { permute[i], permute[j] = permute[j], permute[i] })

			for _, p := range permute {
				bench := &todo.Benchmarks[p.b]
				config := &todo.Configurations[p.c]
				if bench.Disabled || config.Disabled {
					continue
				}
				s := config.compileOne(bench, cwd, p.k)
				if s != "" {
					getAndBuildFailures = append(getAndBuildFailures, s)
				}
			}
		}

		if verbose == 0 {
			fmt.Println()
		}

		// As needed, create the sandbox.
		if needSandbox {
			if verbose == 0 {
				fmt.Print("Making sandbox")
			}
			cmd := exec.Command("docker", "build", "-q", ".")
			if verbose > 0 {
				fmt.Println(asCommandLine(cwd, cmd))
			}
			// capture standard output to get container name
			output, err := cmd.Output()
			if err != nil {
				ee := err.(*exec.ExitError)
				fmt.Printf("There was an error running 'docker build', stderr = %s\n", ee.Stderr)
				os.Exit(2)
				return
			}
			container = strings.TrimSpace(string(output))
			if verbose == 0 {
				fmt.Println()
			}
			fmt.Printf("Container for sandboxed bench/test runs is %s\n", container)
		}
	} else {
		container = runContainer
		if getOnly { // -r -g is a bit of a no-op, but that's what it implies.
			return
		}
	}

	var failures []string

	// If there's a bad error running one of the benchmarks, report what we've got, please.
	defer func(t *Todo) {
		for _, config := range todo.Configurations {
			if !config.Disabled { // Don't overwrite if something was disabled.
				config.benchWriter.Close()
			}
		}
		if needSandbox {
			// Print this a second time so it doesn't get missed.
			fmt.Printf("Container for sandboxed bench/test runs is %s\n", container)
		}
		if len(failures) > 0 {
			fmt.Println("FAILURES:")
			for _, f := range failures {
				fmt.Println(f)
			}
		}
		if len(getAndBuildFailures) > 0 {
			fmt.Println("Get and build failures:")
			for _, f := range getAndBuildFailures {
				fmt.Println(f)
			}
		}
	}(todo)

	maxrc := 0

	// N repetitions for each configurationm, run all the benchmarks.
	// TODO randomize the benchmarks and configurations, like for builds.
	for i := 0; i < N; i++ {
		// For each configuration, run all the benchmarks.
		for j, config := range todo.Configurations {
			if config.Disabled {
				continue
			}

			for _, b := range todo.Benchmarks {
				if b.Disabled {
					continue
				}

				root := config.Root

				wrapperPrefix := "/"
				if b.NotSandboxed {
					wrapperPrefix = cwd + "/"
				}
				wrapperFor := func(s []string) string {
					x := ""
					if len(s) > 0 {
						// If not an explicit path, then make it an explicit path
						x = s[0]
						if x[0] != '/' {
							x = wrapperPrefix + x
						}
					}
					return x
				}

				configWrapper := wrapperFor(config.RunWrapper)
				benchWrapper := wrapperFor(b.RunWrapper)

				testBinaryName := config.benchName(&b)
				var s string
				var rc int

				var wrappersAndBin []string

				if configWrapper != "" {
					wrappersAndBin = append(wrappersAndBin, configWrapper)
					wrappersAndBin = append(wrappersAndBin, config.RunWrapper[1:]...)
				}
				if benchWrapper != "" {
					wrappersAndBin = append(wrappersAndBin, benchWrapper)
					wrappersAndBin = append(wrappersAndBin, b.RunWrapper[1:]...)
				}

				if b.NotSandboxed {
					testdir := gopath + "/src/" + b.Repo
					bin := cwd + "/" + testBinDir + "/" + testBinaryName
					wrappersAndBin = append(wrappersAndBin, bin)

					cmd := exec.Command(wrappersAndBin[0], wrappersAndBin[1:]...)
					cmd.Args = append(cmd.Args, "-test.run="+b.Tests)
					cmd.Args = append(cmd.Args, "-test.bench="+b.Benchmarks)

					cmd.Dir = testdir
					cmd.Env = defaultEnv
					if root != "" {
						cmd.Env = replaceEnv(cmd.Env, "GOROOT", root)
					}
					cmd.Env = replaceEnvs(cmd.Env, config.RunEnv)
					cmd.Env = append(cmd.Env, "BENT_DIR="+cwd)
					cmd.Env = append(cmd.Env, "BENT_BINARY="+testBinaryName)
					cmd.Env = append(cmd.Env, "BENT_I="+strconv.FormatInt(int64(i), 10))
					cmd.Args = append(cmd.Args, config.RunFlags...)
					cmd.Args = append(cmd.Args, moreArgs...)
					s, rc = todo.Configurations[j].runBinary(cwd, cmd, false)
				} else {
					// docker run --net=none -e GOROOT=... -w /src/github.com/minio/minio/cmd $D /testbin/cmd_Config.test -test.short -test.run=Nope -test.v -test.bench=Benchmark'(Get|Put|List)'
					testdir := "/gopath/src/" + b.Repo
					bin := "/" + testBinDir + "/" + testBinaryName
					wrappersAndBin = append(wrappersAndBin, bin)

					cmd := exec.Command("docker", "run", "--net=none",
						"-w", testdir)
					for _, e := range config.RunEnv {
						cmd.Args = append(cmd.Args, "-e", e)
					}
					cmd.Args = append(cmd.Args, "-e", "BENT_DIR=/") // TODO this is not going to work well
					cmd.Args = append(cmd.Args, "-e", "BENT_BINARY="+testBinaryName)
					cmd.Args = append(cmd.Args, "-e", "BENT_I="+strconv.FormatInt(int64(i), 10))
					cmd.Args = append(cmd.Args, container)
					cmd.Args = append(cmd.Args, wrappersAndBin...)
					cmd.Args = append(cmd.Args, "-test.run="+b.Tests)
					cmd.Args = append(cmd.Args, "-test.bench="+b.Benchmarks)
					cmd.Args = append(cmd.Args, config.RunFlags...)
					cmd.Args = append(cmd.Args, moreArgs...)
					s, rc = todo.Configurations[j].runBinary(cwd, cmd, false)
				}
				if s != "" {
					fmt.Println(s)
					failures = append(failures, s)
				}
				if rc > maxrc {
					maxrc = rc
				}
			}
		}
	}
	if maxrc > 0 {
		os.Exit(maxrc)
	}
}

func (c *Configuration) buildBenchName() string {
	return c.thingBenchName("build")
}

func (c *Configuration) thingBenchName(suffix string) string {
	if strings.ContainsAny(suffix, "/") {
		suffix = suffix[strings.LastIndex(suffix, "/")+1:]
	}
	return benchDir + "/" + runstamp + "." + c.Name + "." + suffix
}

func (c *Configuration) benchName(b *Benchmark) string {
	return b.Name + "_" + c.Name
}

func (c *Configuration) goCommand() string {
	gocmd := "go"
	if c.Root != "" {
		gocmd = c.Root + "bin/" + gocmd
	}
	return gocmd
}

func (c *Configuration) goCommandCopy() string {
	gocmd := "go"
	if c.rootCopy != "" {
		gocmd = c.rootCopy + "bin/" + gocmd
	}
	return gocmd
}

func (config *Configuration) createFilesForLater() {
	if config.Disabled {
		return
	}
	f, err := os.Create(config.buildBenchName())
	if err != nil {
		fmt.Println("Error creating build benchmark file ", config.buildBenchName(), ", err=", err)
		config.Disabled = true
	} else {
		fmt.Fprintf(f, "goos: %s\n", runtime.GOOS)
		fmt.Fprintf(f, "goarch: %s\n", runtime.GOARCH)
		f.Close() // will be appending later
	}

	for _, cmd := range config.AfterBuild {
		tbn := config.thingBenchName(cmd)
		f, err := os.Create(tbn)
		if err != nil {
			fmt.Printf("Error creating %s benchmark file %s, err=%v\n", cmd, config.thingBenchName(cmd), err)
			continue
		} else {
			f.Close() // will be appending later
		}
	}
}

func (config *Configuration) runOtherBenchmarks(b *Benchmark, cwd string) {
	// Run various other "benchmark" commands on the built binaries, e.g., size, quality of debugging information.
	if config.Disabled {
		return
	}

	for _, cmd := range config.AfterBuild {
		tbn := config.thingBenchName(cmd)
		f, err := os.OpenFile(tbn, os.O_WRONLY|os.O_APPEND, os.ModePerm)
		if err != nil {
			fmt.Printf("There was an error opening %s for append, error %v\n", tbn, err)
			continue
		}

		if !strings.ContainsAny(cmd, "/") {
			cmd = cwd + "/" + cmd
		}
		if b.Disabled {
			continue
		}
		testBinaryName := config.benchName(b)
		c := exec.Command(cmd, testBinDir+"/"+testBinaryName, b.Name)

		c.Env = defaultEnv
		if !b.NotSandboxed {
			c.Env = replaceEnv(c.Env, "GOOS", "linux")
		}
		// Match the build environment here.
		c.Env = replaceEnvs(c.Env, b.GcEnv)
		c.Env = replaceEnvs(c.Env, config.GcEnv)

		if verbose > 0 {
			fmt.Println(asCommandLine(cwd, c))
		}
		output, err := c.CombinedOutput()
		if verbose > 0 || err != nil {
			fmt.Println(string(output))
		} else {
			fmt.Print(".")
		}
		if err != nil {
			fmt.Printf("Error running %s\n", cmd)
			continue
		}
		f.Write(output)
		f.Sync()
		f.Close()
	}
}

func (config *Configuration) compileOne(bench *Benchmark, cwd string, count int) string {
	root := config.rootCopy
	gocmd := config.goCommandCopy()
	gopath := cwd + "/gopath"

	if explicitAll != 1 { // clear cache unless "-a[=1]" which requests -a on compilation.
		cmd := exec.Command(gocmd, "clean", "-cache")
		cmd.Env = defaultEnv
		if !bench.NotSandboxed {
			cmd.Env = replaceEnv(cmd.Env, "GOOS", "linux")
		}
		if root != "" {
			cmd.Env = replaceEnv(cmd.Env, "GOROOT", root)
		}
		cmd.Env = replaceEnvs(cmd.Env, bench.GcEnv)
		cmd.Env = replaceEnvs(cmd.Env, config.GcEnv)
		cmd.Dir = gopath // Only want the cache-cleaning effect, not the binary-deleting effect. It's okay to clean gopath.
		s, _ := config.runBinary("", cmd, true)
		if s != "" {
			fmt.Println("Error running go clean -cache, ", s)
		}
	}

	// Prefix with time for build benchmarking:
	cmd := exec.Command("/usr/bin/time", "-p", gocmd, "test", "-vet=off", "-c")
	cmd.Args = append(cmd.Args, bench.BuildFlags...)
	// Do not normally need -a because cache was emptied first and std was -a installed with these flags.
	// But for -a=1, do it anyway
	if explicitAll == 1 {
		cmd.Args = append(cmd.Args, "-a")
	}
	cmd.Args = append(cmd.Args, config.BuildFlags...)
	if config.GcFlags != "" {
		cmd.Args = append(cmd.Args, "-gcflags="+config.GcFlags)
	}
	cmd.Args = append(cmd.Args, ".")
	cmd.Dir = gopath + "/src/" + bench.Repo
	cmd.Env = defaultEnv
	if !bench.NotSandboxed {
		cmd.Env = replaceEnv(cmd.Env, "GOOS", "linux")
	}
	if root != "" {
		cmd.Env = replaceEnv(cmd.Env, "GOROOT", root)
	}
	cmd.Env = replaceEnvs(cmd.Env, bench.GcEnv)
	cmd.Env = replaceEnvs(cmd.Env, config.GcEnv)

	if verbose > 0 {
		fmt.Println(asCommandLine(cwd, cmd))
	} else {
		fmt.Print(".")
	}

	defer cleanup(gopath)

	output, err := cmd.CombinedOutput()
	if err != nil {
		s := ""
		switch e := err.(type) {
		case *exec.ExitError:
			s = fmt.Sprintf("There was an error running 'go test', output = %s", output)
		default:
			s = fmt.Sprintf("There was an error running 'go test', output = %s, error = %v", output, e)
		}
		fmt.Println(s + "DISABLING benchmark " + bench.Name)
		bench.Disabled = true // if it won't compile, it won't run, either.
		return s + "(" + bench.Name + ")\n"
	}
	soutput := string(output)
	// Capture times from the end of the output.
	rbt := extractTime(soutput, "real")
	ubt := extractTime(soutput, "user")
	sbt := extractTime(soutput, "sys")
	config.buildStats = append(config.buildStats,
		BenchStat{Name: bench.Name, RealTime: rbt, UserTime: ubt, SysTime: sbt})

	// Report and record build stats to testbin

	buf := new(bytes.Buffer)
	configGoArch := getenv(config.GcEnv, "GOARCH")
	if configGoArch != runtime.GOARCH && configGoArch != "" {
		s := fmt.Sprintf("goarch: %s-%s\n", runtime.GOARCH, configGoArch)
		if verbose > 0 {
			fmt.Print(s)
		}
		buf.WriteString(s)
	}
	s := fmt.Sprintf("Benchmark%s 1 %d build-real-ns/op %d build-user-ns/op %d build-sys-ns/op\n",
		strings.Title(bench.Name), rbt, ubt, sbt)
	if verbose > 0 {
		fmt.Print(s)
	}
	buf.WriteString(s)
	f, err := os.OpenFile(config.buildBenchName(), os.O_WRONLY|os.O_APPEND, os.ModePerm)
	if err != nil {
		fmt.Printf("There was an error opening %s for append, error %v\n", config.buildBenchName(), err)
		cleanup(gopath)
		os.Exit(2)
	}
	f.Write(buf.Bytes())
	f.Sync()
	f.Close()

	// Move generated binary to well-known place.
	from := cmd.Dir + "/" + bench.testBinaryName()
	to := testBinDir + "/" + config.benchName(bench)
	err = os.Rename(from, to)
	if err != nil {
		fmt.Printf("There was an error renaming %s to %s, %v\n", from, to, err)
		cleanup(gopath)
		os.Exit(1)
	}
	// Trim /usr/bin/time info from soutput, it's ugly
	if verbose > 0 {
		fmt.Println("mv " + from + " " + to + "")
		i := strings.LastIndex(soutput, "real")
		if i >= 0 {
			soutput = soutput[:i]
		}
		fmt.Print(soutput)
	}

	// Do this here before any cleanup.
	if count == 0 {
		config.runOtherBenchmarks(bench, cwd)
	}

	return ""
}

func escape(s string) string {
	s = strings.Replace(s, "\\", "\\\\", -1)
	s = strings.Replace(s, "'", "\\'", -1)
	// Conservative guess at characters that will force quoting
	if strings.ContainsAny(s, "\\ ;#*&$~?!|[]()<>{}`") {
		s = " '" + s + "'"
	} else {
		s = " " + s
	}
	return s
}

// asCommandLine renders cmd as something that could be copy-and-pasted into a command line
func asCommandLine(cwd string, cmd *exec.Cmd) string {
	s := "("
	if cmd.Dir != "" && cmd.Dir != cwd {
		s += "cd" + escape(cmd.Dir) + ";"
	}
	for _, e := range cmd.Env {
		if !strings.HasPrefix(e, "PATH=") &&
			!strings.HasPrefix(e, "HOME=") &&
			!strings.HasPrefix(e, "USER=") &&
			!strings.HasPrefix(e, "SHELL=") {
			s += escape(e)
		}
	}
	for _, a := range cmd.Args {
		s += escape(a)
	}
	s += " )"
	return s
}

func copyAsset(file string) {
	bytes, err := Asset(file)
	if err != nil {
		fmt.Printf("Error reading asset %s\n", file)
		os.Exit(1)
	}
	err = ioutil.WriteFile(file, bytes, 0664)
	if err != nil {
		fmt.Printf("Error writing %s\n", file)
		os.Exit(1)
	}
	fmt.Printf("Copied asset %s to current directory\n", file)
}

// runBinary runs cmd and displays the output.
// If the command returns an error, returns an error string.
func (c *Configuration) runBinary(cwd string, cmd *exec.Cmd, printWorkingDot bool) (string, int) {
	line := asCommandLine(cwd, cmd)
	if verbose > 0 {
		fmt.Println(line)
	} else {
		if printWorkingDot {
			fmt.Print(".")
		}
	}

	rc := 0

	stdout, err := cmd.StdoutPipe()
	if err != nil {
		return fmt.Sprintf("Error [stdoutpipe] running '%s', %v", line, err), rc
	}
	stderr, err := cmd.StderrPipe()
	if err != nil {
		return fmt.Sprintf("Error [stderrpipe] running '%s', %v", line, err), rc
	}
	err = cmd.Start()
	if err != nil {
		return fmt.Sprintf("Error [command start] running '%s', %v", line, err), rc
	}

	var mu = &sync.Mutex{}

	f := func(r *bufio.Reader, done chan error) {
		for {
			bytes, err := r.ReadBytes('\n')
			n := len(bytes)
			if n > 0 {
				mu.Lock()
				nw, err := c.benchWriter.Write(bytes[0:n])
				if err != nil {
					fmt.Printf("Error writing, err = %v, nwritten = %d, nrequested = %d\n", err, nw, n)
				}
				c.benchWriter.Sync()
				fmt.Print(string(bytes[0:n]))
				mu.Unlock()
			}
			if err == io.EOF || n == 0 {
				break
			}
			if err != nil {
				done <- err
				return
			}
		}
		done <- nil
	}

	doneS := make(chan error)
	doneE := make(chan error)

	go f(bufio.NewReader(stdout), doneS)
	go f(bufio.NewReader(stderr), doneE)

	errS := <-doneS
	errE := <-doneE

	err = cmd.Wait()
	rc = cmd.ProcessState.ExitCode()

	if err != nil {
		switch e := err.(type) {
		case *exec.ExitError:
			return fmt.Sprintf("Error running '%s', stderr = %s, rc = %d", line, e.Stderr, rc), rc
		default:
			return fmt.Sprintf("Error running '%s', %v, rc = %d", line, e, rc), rc

		}
	}
	if errS != nil {
		return fmt.Sprintf("Error [read stdout] running '%s', %v, rc = %d", line, errS, rc), rc
	}
	if errE != nil {
		return fmt.Sprintf("Error [read stderr] running '%s', %v, rc = %d", line, errE, rc), rc
	}
	return "", rc
}

// testBinaryName returns the name of the binary produced by "go test -c"
func (b *Benchmark) testBinaryName() string {
	return b.Repo[strings.LastIndex(b.Repo, "/")+1:] + ".test"
}

// extractTime extracts a time (from /usr/bin/time -p) based on the tag
// and returns the time converted to nanoseconds.  Missing times and bad
// data result in NaN.
func extractTime(output, label string) int64 {
	// find tag in first column
	li := strings.LastIndex(output, label)
	if li < 0 {
		return -1
	}
	output = output[li+len(label):]
	// lose intervening white space
	li = strings.IndexAny(output, "0123456789-.eEdD")
	if li < 0 {
		return -1
	}
	output = output[li:]
	li = strings.IndexAny(output, "\n\r\t ")
	if li >= 0 { // failing to find EOL is a special case of done.
		output = output[:li]
	}
	x, err := strconv.ParseFloat(output, 64)
	if err != nil {
		return -1
	}
	return int64(x * 1000 * 1000 * 1000)
}

// inheritEnv extracts ev from the os environment and
// returns env extended with that new environment variable.
// Does not check if ev already exists in env.
func inheritEnv(env []string, ev string) []string {
	evv := os.Getenv(ev)
	if evv != "" {
		env = append(env, ev+"="+evv)
	}
	return env
}

func getenv(env []string, ev string) string {
	evplus := ev + "="
	for _, v := range env {
		if strings.HasPrefix(v, evplus) {
			return v[len(evplus):]
		}
	}
	return ""
}

// replaceEnv returns a new environment derived from env
// by removing any existing definition of ev and adding ev=evv.
func replaceEnv(env []string, ev string, evv string) []string {
	evplus := ev + "="
	var newenv []string
	for _, v := range env {
		if !strings.HasPrefix(v, evplus) {
			newenv = append(newenv, v)
		}
	}
	newenv = append(newenv, evplus+evv)
	return newenv
}

// replaceEnv returns a new environment derived from env
// by removing any existing definition of ev and adding ev=evv.
func replaceEnvs(env, newevs []string) []string {
	for _, e := range newevs {
		var newenv []string
		eq := strings.IndexByte(e, '=')
		if eq == -1 {
			panic("Bad input to replaceEnvs, ought to be slice of e=v")
		}
		evplus := e[0 : eq+1]
		for _, v := range env {
			if !strings.HasPrefix(v, evplus) {
				newenv = append(newenv, v)
			}
		}
		env = append(newenv, e)
	}
	return env
}

// ifMissingAddEnv returns a new environment derived from env
// by adding ev=evv if env does not define env.
func ifMissingAddEnv(env []string, ev string, evv string) []string {
	evplus := ev + "="
	for _, v := range env {
		if strings.HasPrefix(v, evplus) {
			return env
		}
	}
	env = append(env, evplus+evv)
	return env
}

// csToset converts a comma-separated string into the set of strings between the commas.
func csToSet(s string) map[string]bool {
	if s == "" {
		return nil
	}
	m := make(map[string]bool)
	ss := strings.Split(s, ",")
	for _, sss := range ss {
		m[sss] = true
	}
	return m
}

// count is a flag.Value that is like a flag.Bool and a flag.Int.
// If used as -name, it increments the count, but -name=x sets the count.
// Used for verbose flag -v and build-all flag -a
type count int

func (c *count) String() string {
	return fmt.Sprint(int(*c))
}

func (c *count) Set(s string) error {
	switch s {
	case "true":
		*c++
	case "false":
		*c = 0
	default:
		n, err := strconv.Atoi(s)
		if err != nil {
			return fmt.Errorf("invalid count %q", s)
		}
		*c = count(n)
	}
	return nil
}

func (c *count) IsBoolFlag() bool {
	return true
}