152 lines
3.3 KiB
Go
152 lines
3.3 KiB
Go
package gobot
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import "sync"
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type eventChannel chan *Event
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type eventer struct {
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// map of valid Event names
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eventnames map[string]string
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// new events get put in to the event channel
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in eventChannel
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// map of out channels used by subscribers
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outs map[eventChannel]eventChannel
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// mutex to protect the eventChannel map
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eventsMutex sync.Mutex
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}
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const eventChanBufferSize = 10
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// Eventer is the interface which describes how a Driver or Adaptor
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// handles events.
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type Eventer interface {
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// Events returns the map of valid Event names.
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Events() (eventnames map[string]string)
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// Event returns an Event string from map of valid Event names.
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// Mostly used to validate that an Event name is valid.
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Event(name string) string
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// AddEvent registers a new Event name.
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AddEvent(name string)
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// DeleteEvent removes a previously registered Event name.
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DeleteEvent(name string)
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// Publish new events to any subscriber
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Publish(name string, data interface{})
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// Subscribe to events
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Subscribe() (events eventChannel)
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// Unsubscribe from an event channel
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Unsubscribe(events eventChannel)
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// Event handler
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On(name string, f func(s interface{})) error
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// Event handler, only executes one time
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Once(name string, f func(s interface{})) error
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}
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// NewEventer returns a new Eventer.
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func NewEventer() Eventer {
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evtr := &eventer{
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eventnames: make(map[string]string),
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in: make(eventChannel, eventChanBufferSize),
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outs: make(map[eventChannel]eventChannel),
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}
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// goroutine to cascade "in" events to all "out" event channels
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go func() {
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for {
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evt := <-evtr.in
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evtr.eventsMutex.Lock()
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for _, out := range evtr.outs {
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out <- evt
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}
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evtr.eventsMutex.Unlock()
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}
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}()
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return evtr
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}
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// Events returns the map of valid Event names.
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func (e *eventer) Events() map[string]string {
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return e.eventnames
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}
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// Event returns an Event string from map of valid Event names.
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// Mostly used to validate that an Event name is valid.
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func (e *eventer) Event(name string) string {
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return e.eventnames[name]
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}
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// AddEvent registers a new Event name.
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func (e *eventer) AddEvent(name string) {
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e.eventnames[name] = name
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}
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// DeleteEvent removes a previously registered Event name.
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func (e *eventer) DeleteEvent(name string) {
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delete(e.eventnames, name)
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}
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// Publish new events to anyone that is subscribed
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func (e *eventer) Publish(name string, data interface{}) {
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evt := NewEvent(name, data)
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e.in <- evt
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}
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// Subscribe to any events from this eventer
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func (e *eventer) Subscribe() eventChannel {
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e.eventsMutex.Lock()
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defer e.eventsMutex.Unlock()
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out := make(eventChannel, eventChanBufferSize)
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e.outs[out] = out
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return out
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}
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// Unsubscribe from the event channel
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func (e *eventer) Unsubscribe(events eventChannel) {
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e.eventsMutex.Lock()
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defer e.eventsMutex.Unlock()
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delete(e.outs, events)
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}
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// On executes the event handler f when e is Published to.
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func (e *eventer) On(n string, f func(s interface{})) error {
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out := e.Subscribe()
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go func() {
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for {
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evt := <-out
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if evt.Name == n {
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f(evt.Data)
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}
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}
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}()
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return nil
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}
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// Once is similar to On except that it only executes f one time.
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func (e *eventer) Once(n string, f func(s interface{})) error {
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out := e.Subscribe()
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go func() {
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ProcessEvents:
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for evt := range out {
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if evt.Name == n {
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f(evt.Data)
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e.Unsubscribe(out)
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break ProcessEvents
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}
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}
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}()
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return nil
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}
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