129 lines
2.5 KiB
Go
129 lines
2.5 KiB
Go
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package statemachine
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import (
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"fmt"
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"strings"
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"time"
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)
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const (
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Running StateType = "running"
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Suspended StateType = "suspended"
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Halt EventType = "halt"
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Resume EventType = "resume"
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)
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type Suspendable interface {
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Halt()
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Resume()
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}
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type HaltAction struct{}
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func (a *HaltAction) Execute(ctx EventContext) EventType {
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s, ok := ctx.(*Suspender)
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if !ok {
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fmt.Println("unable to halt, event context is not Suspendable")
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return NoOp
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}
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s.target.Halt()
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return NoOp
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}
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type ResumeAction struct{}
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func (a *ResumeAction) Execute(ctx EventContext) EventType {
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s, ok := ctx.(*Suspender)
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if !ok {
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fmt.Println("unable to resume, event context is not Suspendable")
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return NoOp
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}
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s.target.Resume()
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return NoOp
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}
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type Suspender struct {
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StateMachine
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target Suspendable
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log LogFn
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}
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type LogFn func(fmt string, args ...interface{})
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func NewSuspender(target Suspendable, log LogFn) *Suspender {
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return &Suspender{
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target: target,
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log: log,
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StateMachine: StateMachine{
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Current: Running,
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States: States{
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Running: State{
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Action: &ResumeAction{},
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Events: Events{
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Halt: Suspended,
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},
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},
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Suspended: State{
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Action: &HaltAction{},
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Events: Events{
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Resume: Running,
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},
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},
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},
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},
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}
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}
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func (s *Suspender) RunEvents(eventSpec string) {
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s.log("running event spec: %s", eventSpec)
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for _, et := range parseEventSpec(eventSpec, s.log) {
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if et.delay != 0 {
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//s.log("waiting %s", et.delay.String())
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time.Sleep(et.delay)
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continue
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}
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if et.event == "" {
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s.log("ignoring empty event")
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continue
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}
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s.log("sending event %s", et.event)
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err := s.SendEvent(et.event, s)
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if err != nil {
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s.log("error sending event %s: %s", et.event, err)
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}
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}
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}
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type eventTiming struct {
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delay time.Duration
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event EventType
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}
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func parseEventSpec(spec string, log LogFn) []eventTiming {
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fields := strings.Split(spec, "->")
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out := make([]eventTiming, 0, len(fields))
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for _, f := range fields {
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f = strings.TrimSpace(f)
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words := strings.Split(f, " ")
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// TODO: try to implement a "waiting" state instead of special casing like this
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if words[0] == "wait" {
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if len(words) != 2 {
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log("expected 'wait' to be followed by duration, e.g. 'wait 30s'. ignoring.")
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continue
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}
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d, err := time.ParseDuration(words[1])
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if err != nil {
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log("bad argument for 'wait': %s", err)
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continue
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}
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out = append(out, eventTiming{delay: d})
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} else {
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out = append(out, eventTiming{event: EventType(words[0])})
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}
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}
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return out
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}
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