added event bus for managing websocket events

eventbus/bus.go

@@ -0,0 +1,15 @@
+package eventbus
+
+import "github.com/bradrydzewski/drone/common"
+
+type Event struct {
+	Build *common.Build
+	Repo  *common.Repo
+	Task  *common.Task
+}
+
+type Bus interface {
+	Subscribe(chan *Event)
+	Unsubscribe(chan *Event)
+	Send(*Event)
+}

eventbus/eventbus.go

@@ -0,0 +1,48 @@
+package eventbus
+
+import (
+	"sync"
+)
+
+type EventBus struct {
+	sync.Mutex
+	subs map[chan *Event]bool
+}
+
+// New creates a new EventBus that manages a list of
+// subscribers to which events are published.
+func New() *EventBus {
+	return &EventBus{
+		subs: make(map[chan *Event]bool),
+	}
+}
+
+// Subscribe adds the channel to the list of
+// subscribers. Each subscriber in the list will
+// receive broadcast events.
+func (b *EventBus) Subscribe(c chan *Event) {
+	b.Lock()
+	b.subs[c] = true
+	b.Unlock()
+}
+
+// Unsubscribe removes the channel from the
+// list of subscribers.
+func (b *EventBus) Unsubscribe(c chan *Event) {
+	b.Lock()
+	delete(b.subs, c)
+	b.Unlock()
+}
+
+// Send dispatches a message to all subscribers.
+func (b *EventBus) Send(event *Event) {
+	b.Lock()
+	defer b.Unlock()
+
+	for s, _ := range b.subs {
+		go func(c chan *Event) {
+			defer recover()
+			c <- event
+		}(s)
+	}
+}