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

305 lines
7.4 KiB
Go

package cli
import (
"fmt"
"io/ioutil"
"sort"
"strings"
)
// Command is a subcommand for a cli.App.
type Command struct {
// The name of the command
Name string
// short name of the command. Typically one character (deprecated, use `Aliases`)
ShortName string
// A list of aliases for the command
Aliases []string
// A short description of the usage of this command
Usage string
// Custom text to show on USAGE section of help
UsageText string
// A longer explanation of how the command works
Description string
// A short description of the arguments of this command
ArgsUsage string
// The category the command is part of
Category string
// The function to call when checking for bash command completions
BashComplete BashCompleteFunc
// An action to execute before any sub-subcommands are run, but after the context is ready
// If a non-nil error is returned, no sub-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 function to call when this command is invoked
Action interface{}
// TODO: replace `Action: interface{}` with `Action: ActionFunc` once some kind
// of deprecation period has passed, maybe?
// Execute this function if a usage error occurs.
OnUsageError OnUsageErrorFunc
// List of child commands
Subcommands Commands
// List of flags to parse
Flags []Flag
// Treat all flags as normal arguments if true
SkipFlagParsing bool
// Skip argument reordering which attempts to move flags before arguments,
// but only works if all flags appear after all arguments. This behavior was
// removed n version 2 since it only works under specific conditions so we
// backport here by exposing it as an option for compatibility.
SkipArgReorder bool
// Boolean to hide built-in help command
HideHelp bool
// Boolean to hide this command from help or completion
Hidden bool
// Full name of command for help, defaults to full command name, including parent commands.
HelpName string
commandNamePath []string
// CustomHelpTemplate the text template for the command help topic.
// cli.go uses text/template to render templates. You can
// render custom help text by setting this variable.
CustomHelpTemplate string
}
type CommandsByName []Command
func (c CommandsByName) Len() int {
return len(c)
}
func (c CommandsByName) Less(i, j int) bool {
return c[i].Name < c[j].Name
}
func (c CommandsByName) Swap(i, j int) {
c[i], c[j] = c[j], c[i]
}
// FullName returns the full name of the command.
// For subcommands this ensures that parent commands are part of the command path
func (c Command) FullName() string {
if c.commandNamePath == nil {
return c.Name
}
return strings.Join(c.commandNamePath, " ")
}
// Commands is a slice of Command
type Commands []Command
// Run invokes the command given the context, parses ctx.Args() to generate command-specific flags
func (c Command) Run(ctx *Context) (err error) {
if len(c.Subcommands) > 0 {
return c.startApp(ctx)
}
if !c.HideHelp && (HelpFlag != BoolFlag{}) {
// append help to flags
c.Flags = append(
c.Flags,
HelpFlag,
)
}
set, err := flagSet(c.Name, c.Flags)
if err != nil {
return err
}
set.SetOutput(ioutil.Discard)
if c.SkipFlagParsing {
err = set.Parse(append([]string{"--"}, ctx.Args().Tail()...))
} else if !c.SkipArgReorder {
firstFlagIndex := -1
terminatorIndex := -1
for index, arg := range ctx.Args() {
if arg == "--" {
terminatorIndex = index
break
} else if arg == "-" {
// Do nothing. A dash alone is not really a flag.
continue
} else if strings.HasPrefix(arg, "-") && firstFlagIndex == -1 {
firstFlagIndex = index
}
}
if firstFlagIndex > -1 {
args := ctx.Args()
regularArgs := make([]string, len(args[1:firstFlagIndex]))
copy(regularArgs, args[1:firstFlagIndex])
var flagArgs []string
if terminatorIndex > -1 {
flagArgs = args[firstFlagIndex:terminatorIndex]
regularArgs = append(regularArgs, args[terminatorIndex:]...)
} else {
flagArgs = args[firstFlagIndex:]
}
err = set.Parse(append(flagArgs, regularArgs...))
} else {
err = set.Parse(ctx.Args().Tail())
}
} else {
err = set.Parse(ctx.Args().Tail())
}
nerr := normalizeFlags(c.Flags, set)
if nerr != nil {
fmt.Fprintln(ctx.App.Writer, nerr)
fmt.Fprintln(ctx.App.Writer)
ShowCommandHelp(ctx, c.Name)
return nerr
}
context := NewContext(ctx.App, set, ctx)
context.Command = c
if checkCommandCompletions(context, c.Name) {
return nil
}
if err != nil {
if c.OnUsageError != nil {
err := c.OnUsageError(context, err, false)
HandleExitCoder(err)
return err
}
fmt.Fprintln(context.App.Writer, "Incorrect Usage:", err.Error())
fmt.Fprintln(context.App.Writer)
ShowCommandHelp(context, c.Name)
return err
}
if checkCommandHelp(context, c.Name) {
return nil
}
if c.After != nil {
defer func() {
afterErr := c.After(context)
if afterErr != nil {
HandleExitCoder(err)
if err != nil {
err = NewMultiError(err, afterErr)
} else {
err = afterErr
}
}
}()
}
if c.Before != nil {
err = c.Before(context)
if err != nil {
ShowCommandHelp(context, c.Name)
HandleExitCoder(err)
return err
}
}
if c.Action == nil {
c.Action = helpSubcommand.Action
}
err = HandleAction(c.Action, context)
if err != nil {
HandleExitCoder(err)
}
return err
}
// Names returns the names including short names and aliases.
func (c Command) Names() []string {
names := []string{c.Name}
if c.ShortName != "" {
names = append(names, c.ShortName)
}
return append(names, c.Aliases...)
}
// HasName returns true if Command.Name or Command.ShortName matches given name
func (c Command) HasName(name string) bool {
for _, n := range c.Names() {
if n == name {
return true
}
}
return false
}
func (c Command) startApp(ctx *Context) error {
app := NewApp()
app.Metadata = ctx.App.Metadata
// set the name and usage
app.Name = fmt.Sprintf("%s %s", ctx.App.Name, c.Name)
if c.HelpName == "" {
app.HelpName = c.HelpName
} else {
app.HelpName = app.Name
}
app.Usage = c.Usage
app.Description = c.Description
app.ArgsUsage = c.ArgsUsage
// set CommandNotFound
app.CommandNotFound = ctx.App.CommandNotFound
app.CustomAppHelpTemplate = c.CustomHelpTemplate
// set the flags and commands
app.Commands = c.Subcommands
app.Flags = c.Flags
app.HideHelp = c.HideHelp
app.Version = ctx.App.Version
app.HideVersion = ctx.App.HideVersion
app.Compiled = ctx.App.Compiled
app.Author = ctx.App.Author
app.Email = ctx.App.Email
app.Writer = ctx.App.Writer
app.ErrWriter = ctx.App.ErrWriter
app.categories = CommandCategories{}
for _, command := range c.Subcommands {
app.categories = app.categories.AddCommand(command.Category, command)
}
sort.Sort(app.categories)
// bash completion
app.EnableBashCompletion = ctx.App.EnableBashCompletion
if c.BashComplete != nil {
app.BashComplete = c.BashComplete
}
// set the actions
app.Before = c.Before
app.After = c.After
if c.Action != nil {
app.Action = c.Action
} else {
app.Action = helpSubcommand.Action
}
app.OnUsageError = c.OnUsageError
for index, cc := range app.Commands {
app.Commands[index].commandNamePath = []string{c.Name, cc.Name}
}
return app.RunAsSubcommand(ctx)
}
// VisibleFlags returns a slice of the Flags with Hidden=false
func (c Command) VisibleFlags() []Flag {
return visibleFlags(c.Flags)
}