syncthing/vendor/gopkg.in/urfave/cli.v1/app.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

498 lines
12 KiB
Go

package cli
import (
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"sort"
"time"
)
var (
changeLogURL = "https://github.com/urfave/cli/blob/master/CHANGELOG.md"
appActionDeprecationURL = fmt.Sprintf("%s#deprecated-cli-app-action-signature", changeLogURL)
runAndExitOnErrorDeprecationURL = fmt.Sprintf("%s#deprecated-cli-app-runandexitonerror", changeLogURL)
contactSysadmin = "This is an error in the application. Please contact the distributor of this application if this is not you."
errInvalidActionType = NewExitError("ERROR invalid Action type. "+
fmt.Sprintf("Must be `func(*Context`)` or `func(*Context) error). %s", contactSysadmin)+
fmt.Sprintf("See %s", appActionDeprecationURL), 2)
)
// App is the main structure of a cli application. It is recommended that
// an app be created with the cli.NewApp() function
type App struct {
// The name of the program. Defaults to path.Base(os.Args[0])
Name string
// Full name of command for help, defaults to Name
HelpName string
// Description of the program.
Usage string
// Text to override the USAGE section of help
UsageText string
// Description of the program argument format.
ArgsUsage string
// Version of the program
Version string
// Description of the program
Description string
// List of commands to execute
Commands []Command
// List of flags to parse
Flags []Flag
// Boolean to enable bash completion commands
EnableBashCompletion bool
// Boolean to hide built-in help command
HideHelp bool
// Boolean to hide built-in version flag and the VERSION section of help
HideVersion bool
// Populate on app startup, only gettable through method Categories()
categories CommandCategories
// An action to execute when the bash-completion flag is set
BashComplete BashCompleteFunc
// An action to execute before any subcommands are run, but after the context is ready
// If a non-nil error is returned, no subcommands are run
Before BeforeFunc
// An action to execute after any subcommands are run, but after the subcommand has finished
// It is run even if Action() panics
After AfterFunc
// The action to execute when no subcommands are specified
// Expects a `cli.ActionFunc` but will accept the *deprecated* signature of `func(*cli.Context) {}`
// *Note*: support for the deprecated `Action` signature will be removed in a future version
Action interface{}
// Execute this function if the proper command cannot be found
CommandNotFound CommandNotFoundFunc
// Execute this function if an usage error occurs
OnUsageError OnUsageErrorFunc
// Compilation date
Compiled time.Time
// List of all authors who contributed
Authors []Author
// Copyright of the binary if any
Copyright string
// Name of Author (Note: Use App.Authors, this is deprecated)
Author string
// Email of Author (Note: Use App.Authors, this is deprecated)
Email string
// Writer writer to write output to
Writer io.Writer
// ErrWriter writes error output
ErrWriter io.Writer
// Other custom info
Metadata map[string]interface{}
// Carries a function which returns app specific info.
ExtraInfo func() map[string]string
// CustomAppHelpTemplate the text template for app help topic.
// cli.go uses text/template to render templates. You can
// render custom help text by setting this variable.
CustomAppHelpTemplate string
didSetup bool
}
// Tries to find out when this binary was compiled.
// Returns the current time if it fails to find it.
func compileTime() time.Time {
info, err := os.Stat(os.Args[0])
if err != nil {
return time.Now()
}
return info.ModTime()
}
// NewApp creates a new cli Application with some reasonable defaults for Name,
// Usage, Version and Action.
func NewApp() *App {
return &App{
Name: filepath.Base(os.Args[0]),
HelpName: filepath.Base(os.Args[0]),
Usage: "A new cli application",
UsageText: "",
Version: "0.0.0",
BashComplete: DefaultAppComplete,
Action: helpCommand.Action,
Compiled: compileTime(),
Writer: os.Stdout,
}
}
// Setup runs initialization code to ensure all data structures are ready for
// `Run` or inspection prior to `Run`. It is internally called by `Run`, but
// will return early if setup has already happened.
func (a *App) Setup() {
if a.didSetup {
return
}
a.didSetup = true
if a.Author != "" || a.Email != "" {
a.Authors = append(a.Authors, Author{Name: a.Author, Email: a.Email})
}
newCmds := []Command{}
for _, c := range a.Commands {
if c.HelpName == "" {
c.HelpName = fmt.Sprintf("%s %s", a.HelpName, c.Name)
}
newCmds = append(newCmds, c)
}
a.Commands = newCmds
if a.Command(helpCommand.Name) == nil && !a.HideHelp {
a.Commands = append(a.Commands, helpCommand)
if (HelpFlag != BoolFlag{}) {
a.appendFlag(HelpFlag)
}
}
if !a.HideVersion {
a.appendFlag(VersionFlag)
}
a.categories = CommandCategories{}
for _, command := range a.Commands {
a.categories = a.categories.AddCommand(command.Category, command)
}
sort.Sort(a.categories)
if a.Metadata == nil {
a.Metadata = make(map[string]interface{})
}
if a.Writer == nil {
a.Writer = os.Stdout
}
}
// Run is the entry point to the cli app. Parses the arguments slice and routes
// to the proper flag/args combination
func (a *App) Run(arguments []string) (err error) {
a.Setup()
// handle the completion flag separately from the flagset since
// completion could be attempted after a flag, but before its value was put
// on the command line. this causes the flagset to interpret the completion
// flag name as the value of the flag before it which is undesirable
// note that we can only do this because the shell autocomplete function
// always appends the completion flag at the end of the command
shellComplete, arguments := checkShellCompleteFlag(a, arguments)
// parse flags
set, err := flagSet(a.Name, a.Flags)
if err != nil {
return err
}
set.SetOutput(ioutil.Discard)
err = set.Parse(arguments[1:])
nerr := normalizeFlags(a.Flags, set)
context := NewContext(a, set, nil)
if nerr != nil {
fmt.Fprintln(a.Writer, nerr)
ShowAppHelp(context)
return nerr
}
context.shellComplete = shellComplete
if checkCompletions(context) {
return nil
}
if err != nil {
if a.OnUsageError != nil {
err := a.OnUsageError(context, err, false)
HandleExitCoder(err)
return err
}
fmt.Fprintf(a.Writer, "%s %s\n\n", "Incorrect Usage.", err.Error())
ShowAppHelp(context)
return err
}
if !a.HideHelp && checkHelp(context) {
ShowAppHelp(context)
return nil
}
if !a.HideVersion && checkVersion(context) {
ShowVersion(context)
return nil
}
if a.After != nil {
defer func() {
if afterErr := a.After(context); afterErr != nil {
if err != nil {
err = NewMultiError(err, afterErr)
} else {
err = afterErr
}
}
}()
}
if a.Before != nil {
beforeErr := a.Before(context)
if beforeErr != nil {
ShowAppHelp(context)
HandleExitCoder(beforeErr)
err = beforeErr
return err
}
}
args := context.Args()
if args.Present() {
name := args.First()
c := a.Command(name)
if c != nil {
return c.Run(context)
}
}
if a.Action == nil {
a.Action = helpCommand.Action
}
// Run default Action
err = HandleAction(a.Action, context)
HandleExitCoder(err)
return err
}
// RunAndExitOnError calls .Run() and exits non-zero if an error was returned
//
// Deprecated: instead you should return an error that fulfills cli.ExitCoder
// to cli.App.Run. This will cause the application to exit with the given eror
// code in the cli.ExitCoder
func (a *App) RunAndExitOnError() {
if err := a.Run(os.Args); err != nil {
fmt.Fprintln(a.errWriter(), err)
OsExiter(1)
}
}
// RunAsSubcommand invokes the subcommand given the context, parses ctx.Args() to
// generate command-specific flags
func (a *App) RunAsSubcommand(ctx *Context) (err error) {
// append help to commands
if len(a.Commands) > 0 {
if a.Command(helpCommand.Name) == nil && !a.HideHelp {
a.Commands = append(a.Commands, helpCommand)
if (HelpFlag != BoolFlag{}) {
a.appendFlag(HelpFlag)
}
}
}
newCmds := []Command{}
for _, c := range a.Commands {
if c.HelpName == "" {
c.HelpName = fmt.Sprintf("%s %s", a.HelpName, c.Name)
}
newCmds = append(newCmds, c)
}
a.Commands = newCmds
// parse flags
set, err := flagSet(a.Name, a.Flags)
if err != nil {
return err
}
set.SetOutput(ioutil.Discard)
err = set.Parse(ctx.Args().Tail())
nerr := normalizeFlags(a.Flags, set)
context := NewContext(a, set, ctx)
if nerr != nil {
fmt.Fprintln(a.Writer, nerr)
fmt.Fprintln(a.Writer)
if len(a.Commands) > 0 {
ShowSubcommandHelp(context)
} else {
ShowCommandHelp(ctx, context.Args().First())
}
return nerr
}
if checkCompletions(context) {
return nil
}
if err != nil {
if a.OnUsageError != nil {
err = a.OnUsageError(context, err, true)
HandleExitCoder(err)
return err
}
fmt.Fprintf(a.Writer, "%s %s\n\n", "Incorrect Usage.", err.Error())
ShowSubcommandHelp(context)
return err
}
if len(a.Commands) > 0 {
if checkSubcommandHelp(context) {
return nil
}
} else {
if checkCommandHelp(ctx, context.Args().First()) {
return nil
}
}
if a.After != nil {
defer func() {
afterErr := a.After(context)
if afterErr != nil {
HandleExitCoder(err)
if err != nil {
err = NewMultiError(err, afterErr)
} else {
err = afterErr
}
}
}()
}
if a.Before != nil {
beforeErr := a.Before(context)
if beforeErr != nil {
HandleExitCoder(beforeErr)
err = beforeErr
return err
}
}
args := context.Args()
if args.Present() {
name := args.First()
c := a.Command(name)
if c != nil {
return c.Run(context)
}
}
// Run default Action
err = HandleAction(a.Action, context)
HandleExitCoder(err)
return err
}
// Command returns the named command on App. Returns nil if the command does not exist
func (a *App) Command(name string) *Command {
for _, c := range a.Commands {
if c.HasName(name) {
return &c
}
}
return nil
}
// Categories returns a slice containing all the categories with the commands they contain
func (a *App) Categories() CommandCategories {
return a.categories
}
// VisibleCategories returns a slice of categories and commands that are
// Hidden=false
func (a *App) VisibleCategories() []*CommandCategory {
ret := []*CommandCategory{}
for _, category := range a.categories {
if visible := func() *CommandCategory {
for _, command := range category.Commands {
if !command.Hidden {
return category
}
}
return nil
}(); visible != nil {
ret = append(ret, visible)
}
}
return ret
}
// VisibleCommands returns a slice of the Commands with Hidden=false
func (a *App) VisibleCommands() []Command {
ret := []Command{}
for _, command := range a.Commands {
if !command.Hidden {
ret = append(ret, command)
}
}
return ret
}
// VisibleFlags returns a slice of the Flags with Hidden=false
func (a *App) VisibleFlags() []Flag {
return visibleFlags(a.Flags)
}
func (a *App) hasFlag(flag Flag) bool {
for _, f := range a.Flags {
if flag == f {
return true
}
}
return false
}
func (a *App) errWriter() io.Writer {
// When the app ErrWriter is nil use the package level one.
if a.ErrWriter == nil {
return ErrWriter
}
return a.ErrWriter
}
func (a *App) appendFlag(flag Flag) {
if !a.hasFlag(flag) {
a.Flags = append(a.Flags, flag)
}
}
// Author represents someone who has contributed to a cli project.
type Author struct {
Name string // The Authors name
Email string // The Authors email
}
// String makes Author comply to the Stringer interface, to allow an easy print in the templating process
func (a Author) String() string {
e := ""
if a.Email != "" {
e = " <" + a.Email + ">"
}
return fmt.Sprintf("%v%v", a.Name, e)
}
// HandleAction attempts to figure out which Action signature was used. If
// it's an ActionFunc or a func with the legacy signature for Action, the func
// is run!
func HandleAction(action interface{}, context *Context) (err error) {
if a, ok := action.(ActionFunc); ok {
return a(context)
} else if a, ok := action.(func(*Context) error); ok {
return a(context)
} else if a, ok := action.(func(*Context)); ok { // deprecated function signature
a(context)
return nil
} else {
return errInvalidActionType
}
}