writing bulletin subscription/publish code

bulletin.go

@@ -1,21 +1,84 @@
 package hodu
 
-type Message struct {
+import "container/list"
+import "sync"
+
+type BulletinChan = chan interface{}
+
+type BulletinSubscription struct {
+	c chan interface{}
+	b *Bulletin
+	topic string
+	node *list.Element
 }
 
-type Subscriber struct {
+type BulletinSubscriptionList = *list.List
-}
+type BulletinSubscriptionMap map[string]BulletinSubscriptionList
 
 type Bulletin struct {
+	sbsc_map BulletinSubscriptionMap
+	sbsc_mtx sync.RWMutex
 }
 
 func NewBulletin() *Bulletin {
-	return &Bulletin{}
+	return &Bulletin{
+		sbsc_map:  make(BulletinSubscriptionMap, 0),
+	}
 }
 
-func (b *Bulletin) Subscribe(topic string) {
+func (b *Bulletin) Subscribe(topic string) *BulletinSubscription {
+	var sbsc BulletinSubscription
+	var sbsc_list BulletinSubscriptionList
+	var ok bool
 
+	sbsc.b = b
+	sbsc.c = make(chan interface{})
+	sbsc.topic = topic
+	b.sbsc_mtx.Lock()
+
+	sbsc_list, ok = b.sbsc_map[topic]
+	if !ok {
+		sbsc_list = list.New()
+		b.sbsc_map[topic] = sbsc_list
+	}
+
+
+	sbsc.node = sbsc_list.PushBack(&sbsc)
+	b.sbsc_mtx.Unlock()
+	return &sbsc
+}
+
+func (b *Bulletin) Unsbsccribe(sbsc *BulletinSubscription) {
+	if sbsc.b == b {
+		var sl BulletinSubscriptionList
+		var ok bool
+
+		b.sbsc_mtx.Lock()
+		sl, ok = b.sbsc_map[sbsc.topic]
+		if ok { sl.Remove(sbsc.node) }
+		b.sbsc_mtx.Unlock()
+	}
 }
 
 func (b *Bulletin) Publish(topic string,  data interface{}) {
+	var sl BulletinSubscriptionList
+	var ok bool
+
+	b.sbsc_mtx.Lock()
+	sl, ok = b.sbsc_map[topic]
+	if ok {
+		var sbsc *BulletinSubscription
+		var e *list.Element
+		for e = sl.Front(); e != nil; e = e.Next() {
+			sbsc = e.Value.(*BulletinSubscription)
+			sbsc.c <- data
+		}
+	}
+	b.sbsc_mtx.Unlock()
+}
+
+func (s *BulletinSubscription) Receive() interface{} {
+	var x interface{}
+	x = <- s.c
+	return x
 }

bulletin_test.go

@@ -0,0 +1,27 @@
+package hodu_test
+
+import "fmt"
+import "hodu"
+import "testing"
+
+func TestBulletin(t *testing.T) {
+	var b *hodu.Bulletin
+	var s1 *hodu.BulletinSubscription
+	var s2 *hodu.BulletinSubscription
+
+	b = hodu.NewBulletin()
+
+	s1 = b.Subscribe("t1")
+	s2 = b.Subscribe("t2")
+
+	go func() {
+		fmt.Printf ("s1: %+v\n", s1.Receive())
+	}()
+
+	go func() {
+		fmt.Printf ("s2: %+v\n", s2.Receive())
+	}()
+
+	b.Publish("t1", "donkey")
+}
+