graph2, changes, rpdata-server: Added changes subscription.

models/changes/submit.go

@@ -1,6 +1,7 @@
 package changes
 
 import (
+	"log"
 	"strconv"
 	"time"
 
@@ -80,10 +81,12 @@ func Submit(model, op, author string, listed bool, keys []models.ChangeKey, obje
 			change.Chapters = append(change.Chapters, object)
 		case []models.Chapter:
 			change.Chapters = append(change.Chapters, object...)
+		default:
+			log.Printf("Warning: unrecognized object in change: %#+v", object)
 		}
 	}
 
-	// TODO: Push to subscribers
+	pushToSubscribers(change)
 
 	err = collection.Insert(&change)
 	if err != nil {

models/changes/subscribe.go

@@ -0,0 +1,87 @@
+package changes
+
+import (
+	"context"
+	"sync"
+
+	"git.aiterp.net/rpdata/api/models"
+)
+
+var subMutex sync.Mutex
+var subList []*subscription
+
+type subscription struct {
+	Keys     map[string]bool
+	Channel  chan<- models.Change
+	WildCard bool
+}
+
+// Subscribe subscribes to all changes.
+func Subscribe(ctx context.Context, keys []models.ChangeKey, wildcard bool) <-chan models.Change {
+	channel := make(chan models.Change, 64)
+	sub := &subscription{
+		Keys:     make(map[string]bool, len(keys)),
+		Channel:  channel,
+		WildCard: wildcard,
+	}
+
+	for _, key := range keys {
+		sub.Keys[mapKey(key)] = true
+	}
+
+	subMutex.Lock()
+	subList = append(subList, sub)
+	subMutex.Unlock()
+
+	go func() {
+		<-ctx.Done()
+
+		subMutex.Lock()
+		for i := range subList {
+			if subList[i] == sub {
+				subList = append(subList[:i], subList[i+1:]...)
+			}
+		}
+		subMutex.Unlock()
+	}()
+
+	return channel
+}
+
+func pushToSubscribers(change models.Change) {
+	keys := make([]string, len(change.Keys))
+	for i := range change.Keys {
+		keys[i] = mapKey(change.Keys[i])
+	}
+
+	subMutex.Lock()
+SubLoop:
+	for _, sub := range subList {
+		if sub.WildCard && change.Listed {
+			select {
+			case sub.Channel <- change:
+			default:
+			}
+		} else {
+			for _, key := range keys {
+				if sub.Keys[key] {
+					select {
+					case sub.Channel <- change:
+					default:
+					}
+
+					continue SubLoop
+				}
+			}
+		}
+	}
+	subMutex.Unlock()
+}
+
+func mapKey(ck models.ChangeKey) string {
+	return ck.Model.String() + "." + ck.ID
+}
+
+func init() {
+	subList = make([]*subscription, 0, 16)
+}