[Geth源码]好用到失眠的命令行应用框架cli

Tag: 以太坊源码 Geth cli Go Golang command line source code

近期开始看以太坊源码，然后发现了这个神奇的，好用到失眠的命令行应用框架cli，因此推荐给大家。

Geth源码

Geth源码地址是 https://github.com/ethereum/go-ethereum.git ，下载编译后，产出的 geth 等位于 build/bin 下

下载

mkdir -p $GOPATH/src/github.com/ethereum/
cd $GOPATH/src/github.com/ethereum/
git clone https://github.com/ethereum/go-ethereum.git

或者

go get github.com/ethereum/go-ethereum

编译

$ make all
$ ls build/bin
abigen      evm     mimegen     simulations
bootnode    examples    p2psim      swarm
clef        faucet      puppeth     swarm-smoke
ethkey      geth        rlpdump     wnode

geth 有众多的参数和自命令，属于是比较复杂的大工程。

$ ./build/bin/geth -h
NAME:
   geth - the go-ethereum command line interface

   Copyright 2013-2018 The go-ethereum Authors

USAGE:
   geth [options] command [command options] [arguments...]

VERSION:
   1.8.18-unstable-2868acd8

COMMANDS:
   account           Manage accounts
   attach            Start an interactive JavaScript environment (connect to node)
   bug               opens a window to report a bug on the geth repo
   console           Start an interactive JavaScript environment
   copydb            Create a local chain from a target chaindata folder
   dump              Dump a specific block from storage
   dumpconfig        Show configuration values
   export            Export blockchain into file
   export-preimages  Export the preimage database into an RLP stream
   import            Import a blockchain file
   import-preimages  Import the preimage database from an RLP stream
   init              Bootstrap and initialize a new genesis block
   js                Execute the specified JavaScript files
   license           Display license information
   makecache         Generate ethash verification cache (for testing)
   makedag           Generate ethash mining DAG (for testing)
   monitor           Monitor and visualize node metrics
   removedb          Remove blockchain and state databases
   version           Print version numbers
   wallet            Manage Ethereum presale wallets
   help, h           Shows a list of commands or help for one command

ETHEREUM OPTIONS:
  --config value                                   TOML configuration file
  --datadir "/Users/xingyongtao/Library/Ethereum"  Data directory for the databases and keystore
  --keystore                                       Directory for the keystore (default = inside the datadir)
  --nousb                                          Disables monitoring for and managing USB hardware wallets
  --networkid value                                Network identifier (integer, 1=Frontier, 2=Morden (disused), 3=Ropsten, 4=Rinkeby) (default: 1)
  --testnet                                        Ropsten network: pre-configured proof-of-work test network
  --rinkeby                                        Rinkeby network: pre-configured proof-of-authority test network
  --syncmode "fast"                                Blockchain sync mode ("fast", "full", or "light")
  --gcmode value                                   Blockchain garbage collection mode ("full", "archive") (default: "full")
  --ethstats value                                 Reporting URL of a ethstats service (nodename:secret@host:port)
  --identity value                                 Custom node name
  --lightserv value                                Maximum percentage of time allowed for serving LES requests (0-90) (default: 0)
  --lightpeers value                               Maximum number of LES client peers (default: 100)
  --lightkdf                                       Reduce key-derivation RAM & CPU usage at some expense of KDF strength

DEVELOPER CHAIN OPTIONS:
  --dev               Ephemeral proof-of-authority network with a pre-funded developer account, mining enabled
  --dev.period value  Block period to use in developer mode (0 = mine only if transaction pending) (default: 0)

ETHASH OPTIONS:
  --ethash.cachedir                             Directory to store the ethash verification caches (default = inside the datadir)
  --ethash.cachesinmem value                    Number of recent ethash caches to keep in memory (16MB each) (default: 2)
  --ethash.cachesondisk value                   Number of recent ethash caches to keep on disk (16MB each) (default: 3)
  --ethash.dagdir "/Users/xingyongtao/.ethash"  Directory to store the ethash mining DAGs (default = inside home folder)
  --ethash.dagsinmem value                      Number of recent ethash mining DAGs to keep in memory (1+GB each) (default: 1)
  --ethash.dagsondisk value                     Number of recent ethash mining DAGs to keep on disk (1+GB each) (default: 2)

TRANSACTION POOL OPTIONS:
  --txpool.locals value        Comma separated accounts to treat as locals (no flush, priority inclusion)
  --txpool.nolocals            Disables price exemptions for locally submitted transactions
  --txpool.journal value       Disk journal for local transaction to survive node restarts (default: "transactions.rlp")
  --txpool.rejournal value     Time interval to regenerate the local transaction journal (default: 1h0m0s)
  --txpool.pricelimit value    Minimum gas price limit to enforce for acceptance into the pool (default: 1)
  --txpool.pricebump value     Price bump percentage to replace an already existing transaction (default: 10)
  --txpool.accountslots value  Minimum number of executable transaction slots guaranteed per account (default: 16)
  --txpool.globalslots value   Maximum number of executable transaction slots for all accounts (default: 4096)
  --txpool.accountqueue value  Maximum number of non-executable transaction slots permitted per account (default: 64)
  --txpool.globalqueue value   Maximum number of non-executable transaction slots for all accounts (default: 1024)
  --txpool.lifetime value      Maximum amount of time non-executable transaction are queued (default: 3h0m0s)

PERFORMANCE TUNING OPTIONS:
  --cache value            Megabytes of memory allocated to internal caching (default: 1024)
  --cache.database value   Percentage of cache memory allowance to use for database io (default: 75)
  --cache.gc value         Percentage of cache memory allowance to use for trie pruning (default: 25)
  --trie-cache-gens value  Number of trie node generations to keep in memory (default: 120)

ACCOUNT OPTIONS:
  --unlock value    Comma separated list of accounts to unlock
  --password value  Password file to use for non-interactive password input

API AND CONSOLE OPTIONS:
  --rpc                  Enable the HTTP-RPC server
  --rpcaddr value        HTTP-RPC server listening interface (default: "localhost")
  --rpcport value        HTTP-RPC server listening port (default: 8545)
  --rpcapi value         API's offered over the HTTP-RPC interface
  --ws                   Enable the WS-RPC server
  --wsaddr value         WS-RPC server listening interface (default: "localhost")
  --wsport value         WS-RPC server listening port (default: 8546)
  --wsapi value          API's offered over the WS-RPC interface
  --wsorigins value      Origins from which to accept websockets requests
  --ipcdisable           Disable the IPC-RPC server
  --ipcpath              Filename for IPC socket/pipe within the datadir (explicit paths escape it)
  --rpccorsdomain value  Comma separated list of domains from which to accept cross origin requests (browser enforced)
  --rpcvhosts value      Comma separated list of virtual hostnames from which to accept requests (server enforced). Accepts '*' wildcard. (default: "localhost")
  --jspath loadScript    JavaScript root path for loadScript (default: ".")
  --exec value           Execute JavaScript statement
  --preload value        Comma separated list of JavaScript files to preload into the console

NETWORKING OPTIONS:
  --bootnodes value     Comma separated enode URLs for P2P discovery bootstrap (set v4+v5 instead for light servers)
  --bootnodesv4 value   Comma separated enode URLs for P2P v4 discovery bootstrap (light server, full nodes)
  --bootnodesv5 value   Comma separated enode URLs for P2P v5 discovery bootstrap (light server, light nodes)
  --port value          Network listening port (default: 30303)
  --maxpeers value      Maximum number of network peers (network disabled if set to 0) (default: 25)
  --maxpendpeers value  Maximum number of pending connection attempts (defaults used if set to 0) (default: 0)
  --nat value           NAT port mapping mechanism (any|none|upnp|pmp|extip:<IP>) (default: "any")
  --nodiscover          Disables the peer discovery mechanism (manual peer addition)
  --v5disc              Enables the experimental RLPx V5 (Topic Discovery) mechanism
  --netrestrict value   Restricts network communication to the given IP networks (CIDR masks)
  --nodekey value       P2P node key file
  --nodekeyhex value    P2P node key as hex (for testing)

MINER OPTIONS:
  --mine                         Enable mining
  --miner.threads value          Number of CPU threads to use for mining (default: 0)
  --miner.notify value           Comma separated HTTP URL list to notify of new work packages
  --miner.gasprice "1000000000"  Minimum gas price for mining a transaction
  --miner.gastarget value        Target gas floor for mined blocks (default: 8000000)
  --miner.gaslimit value         Target gas ceiling for mined blocks (default: 8000000)
  --miner.etherbase value        Public address for block mining rewards (default = first account) (default: "0")
  --miner.extradata value        Block extra data set by the miner (default = client version)
  --miner.recommit value         Time interval to recreate the block being mined (default: 3s)
  --miner.noverify               Disable remote sealing verification

GAS PRICE ORACLE OPTIONS:
  --gpoblocks value      Number of recent blocks to check for gas prices (default: 20)
  --gpopercentile value  Suggested gas price is the given percentile of a set of recent transaction gas prices (default: 60)

VIRTUAL MACHINE OPTIONS:
  --vmdebug         Record information useful for VM and contract debugging
  --vm.evm value    External EVM configuration (default = built-in interpreter)
  --vm.ewasm value  External ewasm configuration (default = built-in interpreter)

LOGGING AND DEBUGGING OPTIONS:
  --fakepow                 Disables proof-of-work verification
  --nocompaction            Disables db compaction after import
  --verbosity value         Logging verbosity: 0=silent, 1=error, 2=warn, 3=info, 4=debug, 5=detail (default: 3)
  --vmodule value           Per-module verbosity: comma-separated list of <pattern>=<level> (e.g. eth/*=5,p2p=4)
  --backtrace value         Request a stack trace at a specific logging statement (e.g. "block.go:271")
  --debug                   Prepends log messages with call-site location (file and line number)
  --pprof                   Enable the pprof HTTP server
  --pprofaddr value         pprof HTTP server listening interface (default: "127.0.0.1")
  --pprofport value         pprof HTTP server listening port (default: 6060)
  --memprofilerate value    Turn on memory profiling with the given rate (default: 524288)
  --blockprofilerate value  Turn on block profiling with the given rate (default: 0)
  --cpuprofile value        Write CPU profile to the given file
  --trace value             Write execution trace to the given file

METRICS AND STATS OPTIONS:
  --metrics                          Enable metrics collection and reporting
  --metrics.influxdb                 Enable metrics export/push to an external InfluxDB database
  --metrics.influxdb.endpoint value  InfluxDB API endpoint to report metrics to (default: "http://localhost:8086")
  --metrics.influxdb.database value  InfluxDB database name to push reported metrics to (default: "geth")
  --metrics.influxdb.username value  Username to authorize access to the database (default: "test")
  --metrics.influxdb.password value  Password to authorize access to the database (default: "test")
  --metrics.influxdb.host.tag host   InfluxDB host tag attached to all measurements (default: "localhost")

WHISPER (EXPERIMENTAL) OPTIONS:
  --shh                       Enable Whisper
  --shh.maxmessagesize value  Max message size accepted (default: 1048576)
  --shh.pow value             Minimum POW accepted (default: 0.2)
  --shh.restrict-light        Restrict connection between two whisper light clients

DEPRECATED OPTIONS:
  --minerthreads value     Number of CPU threads to use for mining (deprecated, use --miner.threads) (default: 0)
  --targetgaslimit value   Target gas floor for mined blocks (deprecated, use --miner.gastarget) (default: 8000000)
  --gasprice "1000000000"  Minimum gas price for mining a transaction (deprecated, use --miner.gasprice)
  --etherbase value        Public address for block mining rewards (default = first account, deprecated, use --miner.etherbase) (default: "0")
  --extradata value        Block extra data set by the miner (default = client version, deprecated, use --miner.extradata)

MISC OPTIONS:
  --help, -h  show help


COPYRIGHT:
   Copyright 2013-2018 The go-ethereum Authors

而这一切，都靠cli搞定。

神奇的 cli

打开 geth 的入口文件 cmd/geth/main.go

geth 入口文件 cmd/geth/main.go

可以看到main函数里，使用了 app.Run 并把所有命令行参数都传了进去， app 的相关设置都在 init 中完成。

// ...
var (

    // ...

    // The app that holds all commands and flags.
    app = utils.NewApp(gitCommit, "the go-ethereum command line interface")

    // ...

)

// ...

func init() {
    // Initialize the CLI app and start Geth
    app.Action = geth
    app.HideVersion = true // we have a command to print the version
    app.Copyright = "Copyright 2013-2018 The go-ethereum Authors"

    //...
 
}
func main() {
    if err := app.Run(os.Args); err != nil {
        fmt.Fprintln(os.Stderr, err)
        os.Exit(1)
    }
}

// ...

这个 app对象 来自于 "gopkg.in/urfave/cli.v1" 包，使用的是v1稳定版本，文档见 https://gopkg.in/urfave/cli.v1 。这也是本文重点推荐的框架，使用该框架会让命令行编程变得非常方便。

App 结构

App 位于 app.go ，结构如下，可以看到自定义的信息应有尽有，包括程序名字、作者信息、用法指导、帮助、标志位、前后处理函数等等。

// 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
}

App 对象的用法很简单， 设置对应的属性，然后运行即可 。如果想有自定义的行为，定义函数，然后设置对应的回调变量即可。

geth 除了设置名字、版本号等，最重要的就是 Action 和 Commands 了。其中 Action 是命令默认动作（如无子命令）， Commands 定义了各个子命令以及对应的 Action 。见 https://github.com/ethereum/go-ethereum/blob/master/cmd/geth/main.go#L176

app.Commands = []cli.Command{
        // See chaincmd.go:
        initCommand,
        importCommand,
        exportCommand,
        importPreimagesCommand,
        exportPreimagesCommand,
        copydbCommand,
        removedbCommand,
        dumpCommand,
        // See monitorcmd.go:
        monitorCommand,
        // See accountcmd.go:
        accountCommand,
        walletCommand,
        // See consolecmd.go:
        consoleCommand,
        attachCommand,
        javascriptCommand,
        // See misccmd.go:
        makecacheCommand,
        makedagCommand,
        versionCommand,
        bugCommand,
        licenseCommand,
        // See config.go
        dumpConfigCommand,
    }

可见，这些 command 恰好和前边的 geth -h 输出的命令完全一样，其中help信息输出，靠的是 cli. helpPrinter ，包里甚至还有模板可以定义，非常赞。

cli.AppHelpTemplate = `NAME:
  {{.Name}} - {{.Usage}}
USAGE:
  {{.HelpName}} {{if .VisibleFlags}}[global options]{{end}}{{if .Commands}} command [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}
  {{if len .Authors}}
AUTHOR:
  {{range .Authors}}{{ . }}{{end}}
  {{end}}{{if .Commands}}
COMMANDS:
{{range .Commands}}{{if not .HideHelp}}   {{join .Names ", "}}{{ "\t"}}{{.Usage}}{{ "\n" }}{{end}}{{end}}{{end}}{{if .VisibleFlags}}
GLOBAL OPTIONS:
  {{range .VisibleFlags}}{{.}}
  {{end}}{{end}}{{if .Copyright }}
COPYRIGHT:
  {{.Copyright}}
  {{end}}{{if .Version}}
VERSION:
  {{.Version}}
  {{end}}
`

Geth的结构

了解了 cli 之后， geth 的代码结构就非常清楚了，主程序调用的是 geth 函数，其他子命令调用对应的 command ，挨个研究即可。

// geth is the main entry point into the system if no special subcommand is ran.
// It creates a default node based on the command line arguments and runs it in
// blocking mode, waiting for it to be shut down.
func geth(ctx *cli.Context) error {
    if args := ctx.Args(); len(args) > 0 {
        return fmt.Errorf("invalid command: %q", args[0])
    }
    node := makeFullNode(ctx)
    startNode(ctx, node)
    node.Wait()
    return nil
}

initCommand = cli.Command{
        Action:    utils.MigrateFlags(initGenesis),
        Name:      "init",
        Usage:     "Bootstrap and initialize a new genesis block",
        ArgsUsage: "<genesisPath>",
        Flags: []cli.Flag{
            utils.DataDirFlag,
        },
        Category: "BLOCKCHAIN COMMANDS",
        Description: `
The init command initializes a new genesis block and definition for the network.
This is a destructive action and changes the network in which you will be
participating.

It expects the genesis file as argument.`,
    }

其中， utils.MigrateFlags 是个通用的处理函数，用于设置标志位（把子context的Flag属性设置到全局context上），如注释，是为了兼容旧版本。

// MigrateFlags sets the global flag from a local flag when it's set.
// This is a temporary function used for migrating old command/flags to the
// new format.
//
// e.g. geth account new --keystore /tmp/mykeystore --lightkdf
//
// is equivalent after calling this method with:
//
// geth --keystore /tmp/mykeystore --lightkdf account new
//
// This allows the use of the existing configuration functionality.
// When all flags are migrated this function can be removed and the existing
// configuration functionality must be changed that is uses local flags
func MigrateFlags(action func(ctx *cli.Context) error) func(*cli.Context) error {
    return func(ctx *cli.Context) error {
        for _, name := range ctx.FlagNames() {
            if ctx.IsSet(name) {
                ctx.GlobalSet(name, ctx.String(name))
            }
        }
        return action(ctx)
    }
}

真正起作用的，仍然是 initGenesis 。其他子命令类似。

嗯，这一下子清楚多了。