syncthing/vendor/gopkg.in/urfave/cli.v1/flag.go
Jakob Borg 916ec63af6 cmd/stdiscosrv: New discovery server (fixes #4618)
This is a new revision of the discovery server. Relevant changes and
non-changes:

- Protocol towards clients is unchanged.

- Recommended large scale design is still to be deployed nehind nginx (I
  tested, and it's still a lot faster at terminating TLS).

- Database backend is leveldb again, only. It scales enough, is easy to
  setup, and we don't need any backend to take care of.

- Server supports replication. This is a simple TCP channel - protect it
  with a firewall when deploying over the internet. (We deploy this within
  the same datacenter, and with firewall.) Any incoming client announces
  are sent over the replication channel(s) to other peer discosrvs.
  Incoming replication changes are applied to the database as if they came
  from clients, but without the TLS/certificate overhead.

- Metrics are exposed using the prometheus library, when enabled.

- The database values and replication protocol is protobuf, because JSON
  was quite CPU intensive when I tried that and benchmarked it.

- The "Retry-After" value for failed lookups gets slowly increased from
  a default of 120 seconds, by 5 seconds for each failed lookup,
  independently by each discosrv. This lowers the query load over time for
  clients that are never seen. The Retry-After maxes out at 3600 after a
  couple of weeks of this increase. The number of failed lookups is
  stored in the database, now and then (avoiding making each lookup a
  database put).

All in all this means clients can be pointed towards a cluster using
just multiple A / AAAA records to gain both load sharing and redundancy
(if one is down, clients will talk to the remaining ones).

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4648
2018-01-14 08:52:31 +00:00

800 lines
20 KiB
Go

package cli
import (
"flag"
"fmt"
"reflect"
"runtime"
"strconv"
"strings"
"syscall"
"time"
)
const defaultPlaceholder = "value"
// BashCompletionFlag enables bash-completion for all commands and subcommands
var BashCompletionFlag Flag = BoolFlag{
Name: "generate-bash-completion",
Hidden: true,
}
// VersionFlag prints the version for the application
var VersionFlag Flag = BoolFlag{
Name: "version, v",
Usage: "print the version",
}
// HelpFlag prints the help for all commands and subcommands
// Set to the zero value (BoolFlag{}) to disable flag -- keeps subcommand
// unless HideHelp is set to true)
var HelpFlag Flag = BoolFlag{
Name: "help, h",
Usage: "show help",
}
// FlagStringer converts a flag definition to a string. This is used by help
// to display a flag.
var FlagStringer FlagStringFunc = stringifyFlag
// FlagsByName is a slice of Flag.
type FlagsByName []Flag
func (f FlagsByName) Len() int {
return len(f)
}
func (f FlagsByName) Less(i, j int) bool {
return f[i].GetName() < f[j].GetName()
}
func (f FlagsByName) Swap(i, j int) {
f[i], f[j] = f[j], f[i]
}
// Flag is a common interface related to parsing flags in cli.
// For more advanced flag parsing techniques, it is recommended that
// this interface be implemented.
type Flag interface {
fmt.Stringer
// Apply Flag settings to the given flag set
Apply(*flag.FlagSet)
GetName() string
}
// errorableFlag is an interface that allows us to return errors during apply
// it allows flags defined in this library to return errors in a fashion backwards compatible
// TODO remove in v2 and modify the existing Flag interface to return errors
type errorableFlag interface {
Flag
ApplyWithError(*flag.FlagSet) error
}
func flagSet(name string, flags []Flag) (*flag.FlagSet, error) {
set := flag.NewFlagSet(name, flag.ContinueOnError)
for _, f := range flags {
//TODO remove in v2 when errorableFlag is removed
if ef, ok := f.(errorableFlag); ok {
if err := ef.ApplyWithError(set); err != nil {
return nil, err
}
} else {
f.Apply(set)
}
}
return set, nil
}
func eachName(longName string, fn func(string)) {
parts := strings.Split(longName, ",")
for _, name := range parts {
name = strings.Trim(name, " ")
fn(name)
}
}
// Generic is a generic parseable type identified by a specific flag
type Generic interface {
Set(value string) error
String() string
}
// Apply takes the flagset and calls Set on the generic flag with the value
// provided by the user for parsing by the flag
// Ignores parsing errors
func (f GenericFlag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError takes the flagset and calls Set on the generic flag with the value
// provided by the user for parsing by the flag
func (f GenericFlag) ApplyWithError(set *flag.FlagSet) error {
val := f.Value
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
if err := val.Set(envVal); err != nil {
return fmt.Errorf("could not parse %s as value for flag %s: %s", envVal, f.Name, err)
}
break
}
}
}
eachName(f.Name, func(name string) {
set.Var(f.Value, name, f.Usage)
})
return nil
}
// StringSlice is an opaque type for []string to satisfy flag.Value and flag.Getter
type StringSlice []string
// Set appends the string value to the list of values
func (f *StringSlice) Set(value string) error {
*f = append(*f, value)
return nil
}
// String returns a readable representation of this value (for usage defaults)
func (f *StringSlice) String() string {
return fmt.Sprintf("%s", *f)
}
// Value returns the slice of strings set by this flag
func (f *StringSlice) Value() []string {
return *f
}
// Get returns the slice of strings set by this flag
func (f *StringSlice) Get() interface{} {
return *f
}
// Apply populates the flag given the flag set and environment
// Ignores errors
func (f StringSliceFlag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError populates the flag given the flag set and environment
func (f StringSliceFlag) ApplyWithError(set *flag.FlagSet) error {
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
newVal := &StringSlice{}
for _, s := range strings.Split(envVal, ",") {
s = strings.TrimSpace(s)
if err := newVal.Set(s); err != nil {
return fmt.Errorf("could not parse %s as string value for flag %s: %s", envVal, f.Name, err)
}
}
f.Value = newVal
break
}
}
}
eachName(f.Name, func(name string) {
if f.Value == nil {
f.Value = &StringSlice{}
}
set.Var(f.Value, name, f.Usage)
})
return nil
}
// IntSlice is an opaque type for []int to satisfy flag.Value and flag.Getter
type IntSlice []int
// Set parses the value into an integer and appends it to the list of values
func (f *IntSlice) Set(value string) error {
tmp, err := strconv.Atoi(value)
if err != nil {
return err
}
*f = append(*f, tmp)
return nil
}
// String returns a readable representation of this value (for usage defaults)
func (f *IntSlice) String() string {
return fmt.Sprintf("%#v", *f)
}
// Value returns the slice of ints set by this flag
func (f *IntSlice) Value() []int {
return *f
}
// Get returns the slice of ints set by this flag
func (f *IntSlice) Get() interface{} {
return *f
}
// Apply populates the flag given the flag set and environment
// Ignores errors
func (f IntSliceFlag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError populates the flag given the flag set and environment
func (f IntSliceFlag) ApplyWithError(set *flag.FlagSet) error {
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
newVal := &IntSlice{}
for _, s := range strings.Split(envVal, ",") {
s = strings.TrimSpace(s)
if err := newVal.Set(s); err != nil {
return fmt.Errorf("could not parse %s as int slice value for flag %s: %s", envVal, f.Name, err)
}
}
f.Value = newVal
break
}
}
}
eachName(f.Name, func(name string) {
if f.Value == nil {
f.Value = &IntSlice{}
}
set.Var(f.Value, name, f.Usage)
})
return nil
}
// Int64Slice is an opaque type for []int to satisfy flag.Value and flag.Getter
type Int64Slice []int64
// Set parses the value into an integer and appends it to the list of values
func (f *Int64Slice) Set(value string) error {
tmp, err := strconv.ParseInt(value, 10, 64)
if err != nil {
return err
}
*f = append(*f, tmp)
return nil
}
// String returns a readable representation of this value (for usage defaults)
func (f *Int64Slice) String() string {
return fmt.Sprintf("%#v", *f)
}
// Value returns the slice of ints set by this flag
func (f *Int64Slice) Value() []int64 {
return *f
}
// Get returns the slice of ints set by this flag
func (f *Int64Slice) Get() interface{} {
return *f
}
// Apply populates the flag given the flag set and environment
// Ignores errors
func (f Int64SliceFlag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError populates the flag given the flag set and environment
func (f Int64SliceFlag) ApplyWithError(set *flag.FlagSet) error {
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
newVal := &Int64Slice{}
for _, s := range strings.Split(envVal, ",") {
s = strings.TrimSpace(s)
if err := newVal.Set(s); err != nil {
return fmt.Errorf("could not parse %s as int64 slice value for flag %s: %s", envVal, f.Name, err)
}
}
f.Value = newVal
break
}
}
}
eachName(f.Name, func(name string) {
if f.Value == nil {
f.Value = &Int64Slice{}
}
set.Var(f.Value, name, f.Usage)
})
return nil
}
// Apply populates the flag given the flag set and environment
// Ignores errors
func (f BoolFlag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError populates the flag given the flag set and environment
func (f BoolFlag) ApplyWithError(set *flag.FlagSet) error {
val := false
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
if envVal == "" {
val = false
break
}
envValBool, err := strconv.ParseBool(envVal)
if err != nil {
return fmt.Errorf("could not parse %s as bool value for flag %s: %s", envVal, f.Name, err)
}
val = envValBool
break
}
}
}
eachName(f.Name, func(name string) {
if f.Destination != nil {
set.BoolVar(f.Destination, name, val, f.Usage)
return
}
set.Bool(name, val, f.Usage)
})
return nil
}
// Apply populates the flag given the flag set and environment
// Ignores errors
func (f BoolTFlag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError populates the flag given the flag set and environment
func (f BoolTFlag) ApplyWithError(set *flag.FlagSet) error {
val := true
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
if envVal == "" {
val = false
break
}
envValBool, err := strconv.ParseBool(envVal)
if err != nil {
return fmt.Errorf("could not parse %s as bool value for flag %s: %s", envVal, f.Name, err)
}
val = envValBool
break
}
}
}
eachName(f.Name, func(name string) {
if f.Destination != nil {
set.BoolVar(f.Destination, name, val, f.Usage)
return
}
set.Bool(name, val, f.Usage)
})
return nil
}
// Apply populates the flag given the flag set and environment
// Ignores errors
func (f StringFlag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError populates the flag given the flag set and environment
func (f StringFlag) ApplyWithError(set *flag.FlagSet) error {
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
f.Value = envVal
break
}
}
}
eachName(f.Name, func(name string) {
if f.Destination != nil {
set.StringVar(f.Destination, name, f.Value, f.Usage)
return
}
set.String(name, f.Value, f.Usage)
})
return nil
}
// Apply populates the flag given the flag set and environment
// Ignores errors
func (f IntFlag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError populates the flag given the flag set and environment
func (f IntFlag) ApplyWithError(set *flag.FlagSet) error {
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
envValInt, err := strconv.ParseInt(envVal, 0, 64)
if err != nil {
return fmt.Errorf("could not parse %s as int value for flag %s: %s", envVal, f.Name, err)
}
f.Value = int(envValInt)
break
}
}
}
eachName(f.Name, func(name string) {
if f.Destination != nil {
set.IntVar(f.Destination, name, f.Value, f.Usage)
return
}
set.Int(name, f.Value, f.Usage)
})
return nil
}
// Apply populates the flag given the flag set and environment
// Ignores errors
func (f Int64Flag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError populates the flag given the flag set and environment
func (f Int64Flag) ApplyWithError(set *flag.FlagSet) error {
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
envValInt, err := strconv.ParseInt(envVal, 0, 64)
if err != nil {
return fmt.Errorf("could not parse %s as int value for flag %s: %s", envVal, f.Name, err)
}
f.Value = envValInt
break
}
}
}
eachName(f.Name, func(name string) {
if f.Destination != nil {
set.Int64Var(f.Destination, name, f.Value, f.Usage)
return
}
set.Int64(name, f.Value, f.Usage)
})
return nil
}
// Apply populates the flag given the flag set and environment
// Ignores errors
func (f UintFlag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError populates the flag given the flag set and environment
func (f UintFlag) ApplyWithError(set *flag.FlagSet) error {
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
envValInt, err := strconv.ParseUint(envVal, 0, 64)
if err != nil {
return fmt.Errorf("could not parse %s as uint value for flag %s: %s", envVal, f.Name, err)
}
f.Value = uint(envValInt)
break
}
}
}
eachName(f.Name, func(name string) {
if f.Destination != nil {
set.UintVar(f.Destination, name, f.Value, f.Usage)
return
}
set.Uint(name, f.Value, f.Usage)
})
return nil
}
// Apply populates the flag given the flag set and environment
// Ignores errors
func (f Uint64Flag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError populates the flag given the flag set and environment
func (f Uint64Flag) ApplyWithError(set *flag.FlagSet) error {
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
envValInt, err := strconv.ParseUint(envVal, 0, 64)
if err != nil {
return fmt.Errorf("could not parse %s as uint64 value for flag %s: %s", envVal, f.Name, err)
}
f.Value = uint64(envValInt)
break
}
}
}
eachName(f.Name, func(name string) {
if f.Destination != nil {
set.Uint64Var(f.Destination, name, f.Value, f.Usage)
return
}
set.Uint64(name, f.Value, f.Usage)
})
return nil
}
// Apply populates the flag given the flag set and environment
// Ignores errors
func (f DurationFlag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError populates the flag given the flag set and environment
func (f DurationFlag) ApplyWithError(set *flag.FlagSet) error {
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
envValDuration, err := time.ParseDuration(envVal)
if err != nil {
return fmt.Errorf("could not parse %s as duration for flag %s: %s", envVal, f.Name, err)
}
f.Value = envValDuration
break
}
}
}
eachName(f.Name, func(name string) {
if f.Destination != nil {
set.DurationVar(f.Destination, name, f.Value, f.Usage)
return
}
set.Duration(name, f.Value, f.Usage)
})
return nil
}
// Apply populates the flag given the flag set and environment
// Ignores errors
func (f Float64Flag) Apply(set *flag.FlagSet) {
f.ApplyWithError(set)
}
// ApplyWithError populates the flag given the flag set and environment
func (f Float64Flag) ApplyWithError(set *flag.FlagSet) error {
if f.EnvVar != "" {
for _, envVar := range strings.Split(f.EnvVar, ",") {
envVar = strings.TrimSpace(envVar)
if envVal, ok := syscall.Getenv(envVar); ok {
envValFloat, err := strconv.ParseFloat(envVal, 10)
if err != nil {
return fmt.Errorf("could not parse %s as float64 value for flag %s: %s", envVal, f.Name, err)
}
f.Value = float64(envValFloat)
break
}
}
}
eachName(f.Name, func(name string) {
if f.Destination != nil {
set.Float64Var(f.Destination, name, f.Value, f.Usage)
return
}
set.Float64(name, f.Value, f.Usage)
})
return nil
}
func visibleFlags(fl []Flag) []Flag {
visible := []Flag{}
for _, flag := range fl {
field := flagValue(flag).FieldByName("Hidden")
if !field.IsValid() || !field.Bool() {
visible = append(visible, flag)
}
}
return visible
}
func prefixFor(name string) (prefix string) {
if len(name) == 1 {
prefix = "-"
} else {
prefix = "--"
}
return
}
// Returns the placeholder, if any, and the unquoted usage string.
func unquoteUsage(usage string) (string, string) {
for i := 0; i < len(usage); i++ {
if usage[i] == '`' {
for j := i + 1; j < len(usage); j++ {
if usage[j] == '`' {
name := usage[i+1 : j]
usage = usage[:i] + name + usage[j+1:]
return name, usage
}
}
break
}
}
return "", usage
}
func prefixedNames(fullName, placeholder string) string {
var prefixed string
parts := strings.Split(fullName, ",")
for i, name := range parts {
name = strings.Trim(name, " ")
prefixed += prefixFor(name) + name
if placeholder != "" {
prefixed += " " + placeholder
}
if i < len(parts)-1 {
prefixed += ", "
}
}
return prefixed
}
func withEnvHint(envVar, str string) string {
envText := ""
if envVar != "" {
prefix := "$"
suffix := ""
sep := ", $"
if runtime.GOOS == "windows" {
prefix = "%"
suffix = "%"
sep = "%, %"
}
envText = fmt.Sprintf(" [%s%s%s]", prefix, strings.Join(strings.Split(envVar, ","), sep), suffix)
}
return str + envText
}
func flagValue(f Flag) reflect.Value {
fv := reflect.ValueOf(f)
for fv.Kind() == reflect.Ptr {
fv = reflect.Indirect(fv)
}
return fv
}
func stringifyFlag(f Flag) string {
fv := flagValue(f)
switch f.(type) {
case IntSliceFlag:
return withEnvHint(fv.FieldByName("EnvVar").String(),
stringifyIntSliceFlag(f.(IntSliceFlag)))
case Int64SliceFlag:
return withEnvHint(fv.FieldByName("EnvVar").String(),
stringifyInt64SliceFlag(f.(Int64SliceFlag)))
case StringSliceFlag:
return withEnvHint(fv.FieldByName("EnvVar").String(),
stringifyStringSliceFlag(f.(StringSliceFlag)))
}
placeholder, usage := unquoteUsage(fv.FieldByName("Usage").String())
needsPlaceholder := false
defaultValueString := ""
if val := fv.FieldByName("Value"); val.IsValid() {
needsPlaceholder = true
defaultValueString = fmt.Sprintf(" (default: %v)", val.Interface())
if val.Kind() == reflect.String && val.String() != "" {
defaultValueString = fmt.Sprintf(" (default: %q)", val.String())
}
}
if defaultValueString == " (default: )" {
defaultValueString = ""
}
if needsPlaceholder && placeholder == "" {
placeholder = defaultPlaceholder
}
usageWithDefault := strings.TrimSpace(fmt.Sprintf("%s%s", usage, defaultValueString))
return withEnvHint(fv.FieldByName("EnvVar").String(),
fmt.Sprintf("%s\t%s", prefixedNames(fv.FieldByName("Name").String(), placeholder), usageWithDefault))
}
func stringifyIntSliceFlag(f IntSliceFlag) string {
defaultVals := []string{}
if f.Value != nil && len(f.Value.Value()) > 0 {
for _, i := range f.Value.Value() {
defaultVals = append(defaultVals, fmt.Sprintf("%d", i))
}
}
return stringifySliceFlag(f.Usage, f.Name, defaultVals)
}
func stringifyInt64SliceFlag(f Int64SliceFlag) string {
defaultVals := []string{}
if f.Value != nil && len(f.Value.Value()) > 0 {
for _, i := range f.Value.Value() {
defaultVals = append(defaultVals, fmt.Sprintf("%d", i))
}
}
return stringifySliceFlag(f.Usage, f.Name, defaultVals)
}
func stringifyStringSliceFlag(f StringSliceFlag) string {
defaultVals := []string{}
if f.Value != nil && len(f.Value.Value()) > 0 {
for _, s := range f.Value.Value() {
if len(s) > 0 {
defaultVals = append(defaultVals, fmt.Sprintf("%q", s))
}
}
}
return stringifySliceFlag(f.Usage, f.Name, defaultVals)
}
func stringifySliceFlag(usage, name string, defaultVals []string) string {
placeholder, usage := unquoteUsage(usage)
if placeholder == "" {
placeholder = defaultPlaceholder
}
defaultVal := ""
if len(defaultVals) > 0 {
defaultVal = fmt.Sprintf(" (default: %s)", strings.Join(defaultVals, ", "))
}
usageWithDefault := strings.TrimSpace(fmt.Sprintf("%s%s", usage, defaultVal))
return fmt.Sprintf("%s\t%s", prefixedNames(name, placeholder), usageWithDefault)
}