Go有限状态机类库使用简介

FSM是finite state machine的缩写，有限状态机是我们在应用开发中经常使用的一种模型，这里简要介绍go语言中https://github.com/looplab/fsm

因为整体比较简单，就直接上代码：
代码业务逻辑简要介绍：
例如一开始是创建状态， 然后是运行状态，运行中是作为这个状态机的初始转台的。
从运行状态可以在更新参数的Event事件触发下进入更新参数状态
可以在增加节点的Event事件触发下进入增加节点状态 可以在增加公网访问地址的Event触发下，进入增加网络地址状态 等等类似这样操作，每种状态自行处理完毕后进入下一个状态，例如更新参数状态处理完毕，进入运行中

package main

import (
	"fmt"
	"github.com/looplab/fsm"
	"k8s.io/klog"
)

const EventRefreshParameter = "refresh_parameter"
const EventAddNode = "add_node"
const EventAddPublicIp = "add_public_ip"
const EventSetRunning = "set_running"

const StateRunning = "running"
const StateRefreshingParameter = "refreshing_parameter"
const StateAddingNode = "adding_node"
const StateAddingPublicIp = "adding_public_ip"

func main() {
	fsm := fsm.NewFSM(
		StateRunning,
		fsm.Events{
			{Name: EventRefreshParameter, Src: []string{StateRunning}, Dst: StateRefreshingParameter},
			{Name: EventAddNode, Src: []string{StateRunning}, Dst: StateAddingNode},
			{Name: EventAddPublicIp, Src: []string{StateRunning}, Dst: StateAddingPublicIp},
			{Name: EventSetRunning, Src: []string{StateRefreshingParameter, StateAddingNode, StateAddingPublicIp},
				Dst: StateRunning},
		},
		fsm.Callbacks{ //表示任一的状态或状态事件
			"before_event": func(e *fsm.Event) {
				klog.Infof("before_event")
			},
			"leave_state": func(e *fsm.Event) {
				klog.Infof("leave_state %q", e.Src)
			},
			"enter_state": func(e *fsm.Event) {
				klog.Infof("enter_state %q -> %q with args:%v", e.Src, e.Dst, e.Args)
			},
			//根据自定义状态或事件所定义的状态事件函数
			"refresh_parameter": func(e *fsm.Event) {
				klog.Infof("before_refreshing_parameter, do param refresh action. curr state:%v", e.FSM.Current())
				klog.Infof("param refresh action done ,change state to running")
				e.FSM.SetState(StateRunning)

			},
		},
	)

	klog.Infof("init state %s", fsm.Current())

	klog.Infof("send %v event to state %s", EventRefreshParameter, fsm.Current())
	err := fsm.Event(EventRefreshParameter, "p1=v1.p2=v2")
	if err != nil {
		fmt.Println(err)
	}

	klog.Infof("send %v event to state %s", EventAddNode, fsm.Current())
	err = fsm.Event(EventAddNode)
	if err != nil {
		fmt.Println(err)
	}

	klog.Infof("send %v event to state %s", EventAddPublicIp, fsm.Current())
	err = fsm.Event(EventAddPublicIp)
	if err != nil {
		fmt.Println(err)
	}

	klog.Infof("final state %s", fsm.Current())
}

func SetRunning(fsm *fsm.FSM) {
	klog.Infof("send %v event to state %s", EventSetRunning, fsm.Current())
	err := fsm.Event(EventSetRunning)
	if err != nil {
		fmt.Println(err)
	}
}

运行结果：

I0604 21:34:06.679980   13108 main.go:55] init state running
I0604 21:34:06.679980   13108 main.go:57] send refresh_parameter event to state running
I0604 21:34:06.679980   13108 main.go:33] before_event
I0604 21:34:06.679980   13108 main.go:36] leave_state "running"
I0604 21:34:06.679980   13108 main.go:39] enter_state "running" -> "refreshing_parameter" with args:[p1=v1.p2=v2]
I0604 21:34:06.679980   13108 main.go:46] before_refreshing_parameter, do param refresh action. curr state:refreshing_parameter
I0604 21:34:06.679980   13108 main.go:47] param refresh action done ,change state to running
I0604 21:34:06.679980   13108 main.go:64] send add_node event to state running
I0604 21:34:06.679980   13108 main.go:33] before_event
I0604 21:34:06.679980   13108 main.go:36] leave_state "running"
I0604 21:34:06.679980   13108 main.go:39] enter_state "running" -> "adding_node" with args:[]
I0604 21:34:06.679980   13108 main.go:70] send add_public_ip event to state adding_node
I0604 21:34:06.679980   13108 main.go:76] final state adding_node
event add_public_ip inappropriate in current state adding_node

Process finished with the exit code 0