add tracker methods

reactivity/tracker.go

@@ -1,23 +1,58 @@
 package reactivity
 
-import "github.com/gorilla/websocket"
+import (
+	"sync"
+)
 
 // TODO: populate with needed structures for tracking state
 type Tracker struct {
+	mu sync.RWMutex
+
+	// Maps a Client's UUID to their actual Client struct
+	clients map[string]*Client
+
+	// Maps a Query Hash (e.g. "getUser?id=1") to a Set of Client IDs
+	subscriptions map[string]map[string]bool
 }
 
 func NewTracker() *Tracker {
-	return &Tracker{}
+	return &Tracker{clients: make(map[string]*Client), subscriptions: make(map[string]map[string]bool)}
 }
 
-func (t *Tracker) Track(conn *websocket.Conn) {}
-
-func (t *Tracker) Untrack(conn *websocket.Conn) {}
-
-func (t *Tracker) SubscribeToQuery(query string) {}
-
-func (t *Tracker) UnsubscribeFromQuery(query string) {}
-
-func (t *Tracker) GetQuerySubscriptions() []string {
-	return []string{}
+func (t *Tracker) Track(c *Client) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.clients[c.ID] = c
+}
+
+func (t *Tracker) Untrack(c *Client) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	delete(t.clients, c.ID)
+}
+
+func (t *Tracker) SubscribeToQuery(clientID string, queryHash string) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.subscriptions[queryHash] == nil {
+		t.subscriptions[queryHash] = make(map[string]bool)
+	}
+	t.subscriptions[queryHash][clientID] = true
+}
+
+func (t *Tracker) UnsubscribeFromQuery(clientID string, queryHash string) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	delete(t.subscriptions[queryHash], clientID)
+}
+
+func (t *Tracker) GetQuerySubscriptions(queryHash string) []string {
+	t.mu.RLock()
+	defer t.mu.RUnlock()
+	subscriptions := t.subscriptions[queryHash]
+	subscriptionIDs := make([]string, 0, len(subscriptions))
+	for clientID := range subscriptions {
+		subscriptionIDs = append(subscriptionIDs, clientID)
+	}
+	return subscriptionIDs
 }