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a super easy to use finite state machine implemented in go.
its has the following features:
- Easy to use and quick to understand
- Only one global register is required,no need to register in multiple places
- Support different business->same state value->customize different event handler
Design:
why we need to differentiate our business?
Because most of the business state values from database,such as the order state is in the order table and the product state in the product table,it is possible that the values are the same.
the same business corresponding to the same attribute state value expression single. different business under the attribute state may appear the same value, but the meaning expressed is different.
fsm:=NewFsm("businessName","currentState")
currentState,err:=fsm.Call("eventName","eventParam")Explain：
- Business:For example there are product state business,order state business.....
- State：to be paid , to be shipped....
- Event：The set of state reachable events. For example, the only reachable events for the pending payment state are: payment events and cancellation events (depending on your business)
- Execution event subject：Execute custom event functions, if necessary, you can also customize the execution of events before and after hook, event subscribers (such as when the payment events occurs, asynchronous notification of users, etc.)
go get -u github.com/wuqinqiang/easyfsmExample，
package main
import (
"fmt"
"github.com/wuqinqiang/easyfsm"
)
var (
// business
businessName easyfsm.BusinessName = "order"
// states
initState easyfsm.State = 1 // Initialization
paidState easyfsm.State = 2 // Paid
canceled easyfsm.State = 3 // Canceled
//events
paymentOrderEventName easyfsm.EventName = "paymentOrderEventName"
cancelOrderEventName easyfsm.EventName = "cancelOrderEventName"
)
type (
orderParam struct {
OrderNo string
}
)
func init() {
// Payment order event
entity := easyfsm.NewEventEntity(paymentOrderEventName,
func(opt *easyfsm.Param) (easyfsm.State, error) {
param, ok := opt.Data.(orderParam)
if !ok {
panic("param err")
}
fmt.Printf("param:%+v\n", param)
// Handling core business
return paidState, nil
})
// Cancellation Event
cancelEntity := easyfsm.NewEventEntity(cancelOrderEventName,
func(opt *easyfsm.Param) (easyfsm.State, error) {
// Handling core business
param, ok := opt.Data.(orderParam)
if !ok {
panic("param err")
}
fmt.Printf("param:%+v\n", param)
return canceled, nil
})
// Register Order State Machine
easyfsm.RegisterStateMachine(businessName,
initState,
entity, cancelEntity)
}
func main() {
// Normal operation
// The first step generates the fsm based on the business, and the current state
fsm := easyfsm.NewFSM(businessName, initState)
// Step 2:Call the event
currentState, err := fsm.Call(cancelOrderEventName,
easyfsm.WithData(orderParam{OrderNo: "[email protected]"}))
fmt.Printf("[Success]call cancelOrderEventName err:%v\n", err)
fmt.Printf("[Success]call cancelOrderEventName state:%v\n", currentState)
// Exception 1, no goods business defined
fsm = easyfsm.NewFSM("goods", paidState)
currentState, err = fsm.Call(cancelOrderEventName,
easyfsm.WithData(orderParam{OrderNo: "[email protected]"}))
fmt.Printf("[UnKnowBusiness]faild: %v\n", err)
fmt.Printf("[UnKnowBusiness]faild state:%v\n", currentState)
//Exception 2, no state defined:2
fsm = easyfsm.NewFSM(businessName, easyfsm.State(2))
currentState, err = fsm.Call(cancelOrderEventName,
easyfsm.WithData(orderParam{OrderNo: "[email protected]"}))
fmt.Printf("[UnKnowState]faild: %v\n", err)
fmt.Printf("[UnKnowState]faild state:%v\n", currentState)
// Exception 3,The shipping event corresponding to state 1 is not defined
fsm = easyfsm.NewFSM(businessName, initState)
currentState, err = fsm.Call("shippingEvent",
easyfsm.WithData(orderParam{OrderNo: "[email protected]"}))
fmt.Printf("[UnKnowEvent]faild: %v\n", err)
fmt.Printf("[UnKnowEvent]faild state:%v\n", currentState)
}If you want to execute some hooks before and after the event handling function, or execute some other operations asynchronously after the event execution, easyfsm defines these two interfaces.
type (
EventObserver interface {
Receive(opt *Param)
}
EventHook interface {
Before(opt *Param)
After(opt Param, state State, err error)
}
)We can implement these two interfaces that
type (
NotifyExample struct {
}
HookExample struct {
}
)
func (h HookExample) Before(opt *easyfsm.Param) {
fmt.Println("Before event execution")
}
func (h HookExample) After(opt easyfsm.Param, state easyfsm.State, err error) {
fmt.Println("After event execution")
}
func (o NotifyExample) Receive(opt *easyfsm.Param) {
fmt.Println("Receive events, send messages")
}Full example code：
package main
import (
"fmt"
"time"
"github.com/wuqinqiang/easyfsm"
)
var (
// business
businessName easyfsm.BusinessName = "order"
// states
initState easyfsm.State = 1 // initial state
paidState easyfsm.State = 2 // paid
canceled easyfsm.State = 3 // canceled
//events
paymentOrderEventName easyfsm.EventName = "paymentOrderEventName"
cancelOrderEventName easyfsm.EventName = "cancelOrderEventName"
)
type (
orderParam struct {
OrderNo string
}
)
var (
_ easyfsm.EventObserver = (*NotifyExample)(nil)
_ easyfsm.EventHook = (*HookExample)(nil)
)
type (
NotifyExample struct {
}
HookExample struct {
}
)
func (h HookExample) Before(opt *easyfsm.Param) {
fmt.Println("Before event execution")
}
func (h HookExample) After(opt easyfsm.Param, state easyfsm.State, err error) {
fmt.Println("After event execution")
}
func (o NotifyExample) Receive(opt *easyfsm.Param) {
fmt.Println("Receive events, send messages")
}
func init() {
// Payment order event
entity := easyfsm.NewEventEntity(paymentOrderEventName,
func(opt *easyfsm.Param) (easyfsm.State, error) {
param, ok := opt.Data.(orderParam)
if !ok {
panic("param err")
}
fmt.Printf("param:%+v\n", param)
// Handling core business
return paidState, nil
}, easyfsm.WithHook(HookExample{}), easyfsm.WithObservers(NotifyExample{}))
// Cancellation Event
cancelEntity := easyfsm.NewEventEntity(cancelOrderEventName,
func(opt *easyfsm.Param) (easyfsm.State, error) {
// Handling core business
param, ok := opt.Data.(orderParam)
if !ok {
panic("param err")
}
fmt.Printf("param:%+v\n", param)
return canceled, nil
}, easyfsm.WithHook(HookExample{}))
// Register Order State Machine
easyfsm.RegisterStateMachine(businessName,
initState,
entity, cancelEntity)
}
func main() {
// Normal operation
// The first step generates the fsm based on the business, and the current state
fsm := easyfsm.NewFSM(businessName, initState)
// Step 2:Call the event
currentState, err := fsm.Call(paymentOrderEventName,
easyfsm.WithData(orderParam{OrderNo: "[email protected]"}))
fmt.Printf("[Success]call paymentOrderEventName err:%v\n", err)
fmt.Printf("[Success]call paymentOrderEventName state:%v\n", currentState)
time.Sleep(2 * time.Second)
}If there are different needs, you are welcome to leave a message in issue.