core: Refactor events to use channels all the way down. Allows 'metal…

…' development using Gobot libs.

Signed-off-by: deadprogram <[email protected]>

event.go

@@ -1,35 +1,13 @@
 package gobot
 
-import "sync"
-
-type callback struct {
-	f    func(interface{})
-	once bool
-}
-
-// Event executes the list of Callbacks when Chan is written to.
+// Event represents when something asyncronous happens in a Driver
+// or Adaptor
 type Event struct {
-	sync.Mutex
-	Callbacks []callback
+	Name string
+	Data interface{}
 }
 
-// NewEvent returns a new Event which is now listening for data.
-func NewEvent() *Event {
-	return &Event{}
-}
-
-// Write writes data to the Event, it will not block and will not buffer if there
-// are no active subscribers to the Event.
-func (e *Event) Write(data interface{}) {
-	e.Lock()
-	defer e.Unlock()
-
-	tmp := []callback{}
-	for _, cb := range e.Callbacks {
-		go cb.f(data)
-		if !cb.once {
-			tmp = append(tmp, cb)
-		}
-	}
-	e.Callbacks = tmp
+// NewEvent returns a new Event and its associated data.
+func NewEvent(name string, data interface{}) *Event {
+	return &Event{Name: name, Data: data}
 }

eventer.go

@@ -1,36 +1,112 @@
 package gobot
 
+type eventChannel chan *Event
+
 type eventer struct {
-	events map[string]*Event
+	// map of valid Event names
+	eventnames map[string]string
+
+	// new events get put in to the event channel
+	in eventChannel
+
+	// slice of out channels used by subscribers
+	outs []eventChannel
 }
 
-// Eventer is the interface which describes behaviour for a Driver or Adaptor
-// which uses events.
+// Eventer is the interface which describes how a Driver or Adaptor
+// handles events.
 type Eventer interface {
-	// Events returns the Event map.
-	Events() (events map[string]*Event)
-	// Event returns an Event by name. Returns nil if the Event is not found.
-	Event(name string) (event *Event)
-	// AddEvent adds a new Event given a name.
+	// Events returns the map of valid Event names.
+	Events() (eventnames map[string]string)
+	// Event returns the map of valid Event names.
+	Event(name string) string
+	// AddEvent registers a new Event name.
 	AddEvent(name string)
+	// Publish new events to anyone listening
+	Publish(name string, data interface{})
+	// Subscribe to any events from this eventer
+	Subscribe() (events eventChannel)
 }
 
 // NewEventer returns a new Eventer.
 func NewEventer() Eventer {
-	return &eventer{
-		events: make(map[string]*Event),
+	evtr := &eventer{
+		eventnames: make(map[string]string),
+		in:         make(eventChannel, 1),
+		outs:       make([]eventChannel, 1),
 	}
+
+	// goroutine to cascade in events to all out event channels
+	go func() {
+		for {
+			select {
+			case evt := <-evtr.in:
+				for _, out := range evtr.outs[1:] {
+					out <- evt
+				}
+			}
+		}
+	}()
+
+	return evtr
 }
 
-func (e *eventer) Events() map[string]*Event {
-	return e.events
+func (e *eventer) Events() map[string]string {
+	return e.eventnames
 }
 
-func (e *eventer) Event(name string) (event *Event) {
-	event, _ = e.events[name]
-	return
+func (e *eventer) Event(name string) string {
+	return e.eventnames[name]
 }
 
 func (e *eventer) AddEvent(name string) {
-	e.events[name] = NewEvent()
+	e.eventnames[name] = name
+}
+
+func (e *eventer) Publish(name string, data interface{}) {
+	evt := NewEvent(name, data)
+	e.in <- evt
+}
+
+func (e *eventer) Subscribe() eventChannel {
+	out := make(eventChannel)
+	e.outs = append(e.outs, out)
+	return out
+}
+
+// On executes f when e is Published to. Returns ErrUnknownEvent if Event
+// does not exist.
+func (e *eventer) On(n string, f func(s interface{})) (err error) {
+	out := e.Subscribe()
+	go func() {
+		for {
+			select {
+			case evt := <-out:
+				if evt.Name == n {
+					f(evt.Data)
+				}
+			}
+		}
+	}()
+
+	return
+}
+
+// Once is similar to On except that it only executes f one time. Returns
+//ErrUnknownEvent if Event does not exist.
+func (e *eventer) Once(n string, f func(s interface{})) (err error) {
+	out := e.Subscribe()
+	go func() {
+		for {
+			select {
+			case evt := <-out:
+				if evt.Name == n {
+					f(evt.Data)
+					break
+				}
+			}
+		}
+	}()
+
+	return
 }

eventer_test.go

@@ -2,21 +2,13 @@ package gobot
 
 import (
 	"testing"
-
-	"github.com/hybridgroup/gobot/gobottest"
 )
 
 func TestEventer(t *testing.T) {
 	e := NewEventer()
 	e.AddEvent("test")
 
 	if _, ok := e.Events()["test"]; !ok {
-		t.Errorf("Could not add event to list of Events")
+		t.Errorf("Could not add event to list of Event names")
 	}
-
-	event := e.Event("test")
-	gobottest.Refute(t, event, nil)
-
-	event = e.Event("booyeah")
-	gobottest.Assert(t, event, (*Event)(nil))
 }

examples/metal_button.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"fmt"
+	"github.com/hybridgroup/gobot/platforms/gpio"
+	"github.com/hybridgroup/gobot/platforms/intel-iot/edison"
+)
+
+func main() {
+	e := edison.NewEdisonAdaptor("edison")
+	led := gpio.NewLedDriver(e, "led", "13")
+	button := gpio.NewButtonDriver(e, "button", "5")
+
+	e.Connect()
+	led.Start()
+	button.Start()
+
+	led.Off()
+
+	buttonEvents := button.Subscribe()
+	for {
+		select {
+		case event := <-buttonEvents:
+			fmt.Println("Event:", event.Name, event.Data)
+			if event.Name == "push" {
+				led.Toggle()
+			}
+		}
+	}
+}

examples_test.go

@@ -21,30 +21,6 @@ func ExampleAfter() {
 	})
 }
 
-func ExamplePublish() {
-	e := gobot.NewEvent()
-	gobot.Publish(e, 100)
-}
-
-func ExampleOn() {
-	e := gobot.NewEvent()
-	gobot.On(e, func(s interface{}) {
-		fmt.Println(s)
-	})
-	gobot.Publish(e, 100)
-	gobot.Publish(e, 200)
-}
-
-func ExampleOnce() {
-	e := gobot.NewEvent()
-	gobot.Once(e, func(s interface{}) {
-		fmt.Println(s)
-		fmt.Println("I will no longer respond to events")
-	})
-	gobot.Publish(e, 100)
-	gobot.Publish(e, 200)
-}
-
 func ExampleRand() {
 	i := gobot.Rand(100)
 	fmt.Printf("%v is > 0 && < 100", i)

platforms/gpio/analog_sensor_driver.go

@@ -63,10 +63,10 @@ func (a *AnalogSensorDriver) Start() (errs []error) {
 		for {
 			newValue, err := a.Read()
 			if err != nil {
-				gobot.Publish(a.Event(Error), err)
+				a.Publish(a.Event(Error), err)
 			} else if newValue != value && newValue != -1 {
 				value = newValue
-				gobot.Publish(a.Event(Data), value)
+				a.Publish(a.Event(Data), value)
 			}
 			select {
 			case <-time.After(a.interval):

platforms/gpio/analog_sensor_driver_test.go

@@ -39,7 +39,7 @@ func TestAnalogSensorDriverStart(t *testing.T) {
 	gobottest.Assert(t, len(d.Start()), 0)
 
 	// data was received
-	gobot.Once(d.Event(Data), func(data interface{}) {
+	d.Once(d.Event(Data), func(data interface{}) {
 		gobottest.Assert(t, data.(int), 100)
 		sem <- true
 	})
@@ -56,7 +56,7 @@ func TestAnalogSensorDriverStart(t *testing.T) {
 	}
 
 	// read error
-	gobot.Once(d.Event(Error), func(data interface{}) {
+	d.Once(d.Event(Error), func(data interface{}) {
 		gobottest.Assert(t, data.(error).Error(), "read error")
 		sem <- true
 	})
@@ -73,7 +73,7 @@ func TestAnalogSensorDriverStart(t *testing.T) {
 	}
 
 	// send a halt message
-	gobot.Once(d.Event(Data), func(data interface{}) {
+	d.Once(d.Event(Data), func(data interface{}) {
 		sem <- true
 	})
 

platforms/gpio/button_driver.go

@@ -1,9 +1,8 @@
 package gpio
 
 import (
-	"time"
-
 	"github.com/hybridgroup/gobot"
+	"time"
 )
 
 var _ gobot.Driver = (*ButtonDriver)(nil)
@@ -58,7 +57,7 @@ func (b *ButtonDriver) Start() (errs []error) {
 		for {
 			newValue, err := b.connection.DigitalRead(b.Pin())
 			if err != nil {
-				gobot.Publish(b.Event(Error), err)
+				b.Publish(b.Event(Error), err)
 			} else if newValue != state && newValue != -1 {
 				state = newValue
 				b.update(newValue)
@@ -91,9 +90,9 @@ func (b *ButtonDriver) Connection() gobot.Connection { return b.connection.(gobo
 func (b *ButtonDriver) update(newValue int) {
 	if newValue == 1 {
 		b.Active = true
-		gobot.Publish(b.Event(Push), newValue)
+		b.Publish(b.Event(Push), newValue)
 	} else {
 		b.Active = false
-		gobot.Publish(b.Event(Release), newValue)
+		b.Publish(b.Event(Release), newValue)
 	}
 }

platforms/gpio/button_driver_test.go

@@ -42,7 +42,7 @@ func TestButtonDriverStart(t *testing.T) {
 		return
 	}
 
-	gobot.Once(d.Event(Push), func(data interface{}) {
+	d.Once(d.Event(Push), func(data interface{}) {
 		gobottest.Assert(t, d.Active, true)
 		sem <- true
 	})
@@ -58,7 +58,7 @@ func TestButtonDriverStart(t *testing.T) {
 		return
 	}
 
-	gobot.Once(d.Event(Release), func(data interface{}) {
+	d.Once(d.Event(Release), func(data interface{}) {
 		gobottest.Assert(t, d.Active, false)
 		sem <- true
 	})
@@ -74,7 +74,7 @@ func TestButtonDriverStart(t *testing.T) {
 		return
 	}
 
-	gobot.Once(d.Event(Error), func(data interface{}) {
+	d.Once(d.Event(Error), func(data interface{}) {
 		sem <- true
 	})
 
@@ -89,7 +89,7 @@ func TestButtonDriverStart(t *testing.T) {
 		return
 	}
 
-	gobot.Once(d.Event(Push), func(data interface{}) {
+	d.Once(d.Event(Push), func(data interface{}) {
 		sem <- true
 	})
 

platforms/gpio/grove_drivers.go

@@ -111,11 +111,11 @@ func NewGrovePiezoVibrationSensorDriver(a AnalogReader, name string, pin string,
 
 	sensor.AddEvent(Vibration)
 
-	gobot.On(sensor.Event(Data), func(data interface{}) {
-		if data.(int) > 1000 {
-			gobot.Publish(sensor.Event(Vibration), data)
-		}
-	})
+	// sensor.On(sensor.Event(Data), func(data interface{}) {
+	// 	if data.(int) > 1000 {
+	// 		sensor.Publish(sensor.Event(Vibration), data)
+	// 	}
+	// })
 
 	return sensor
 }

platforms/gpio/grove_temperature_sensor_driver.go

@@ -64,10 +64,10 @@ func (a *GroveTemperatureSensorDriver) Start() (errs []error) {
 			newValue := 1/(math.Log(resistance/10000.0)/thermistor+1/298.15) - 273.15
 
 			if err != nil {
-				gobot.Publish(a.Event(Error), err)
+				a.Publish(a.Event(Error), err)
 			} else if newValue != a.temperature && newValue != -1 {
 				a.temperature = newValue
-				gobot.Publish(a.Event(Data), a.temperature)
+				a.Publish(a.Event(Data), a.temperature)
 			}
 			select {
 			case <-time.After(a.interval):