Function initTopicP2P

server/init_topic.go:227–499

Load or create a P2P topic. There is a reace condition when two users try to create a p2p topic at the same time.

(t *Topic, sreg *ClientComMessage)

// Load or create a P2P topic.
// There is a reace condition when two users try to create a p2p topic at the same time.
func initTopicP2P(t *Topic, sreg *ClientComMessage) error {
	pktsub := sreg.Sub

	// Handle the following cases:
	// 1. Neither topic nor subscriptions exist: create a new p2p topic & subscriptions.
	// 2. Topic exists, one of the subscriptions is missing:
	// 2.1 Requester's subscription is missing, recreate it.
	// 2.2 Other user's subscription is missing, treat like a new request for user 2.
	// 3. Topic exists, both subscriptions are missing: should not happen, fail.
	// 4. Topic and both subscriptions exist: attach to topic

	t.cat = types.TopicCatP2P

	// Check if the topic already exists
	stopic, err := store.Topics.Get(t.name)
	if err != nil {
		return err
	}

	// If topic exists, load subscriptions
	var subs []types.Subscription
	if stopic != nil {
		// Subs already have Public swapped
		if subs, err = store.Topics.GetUsers(t.name, nil); err != nil {
			return err
		}

		// Case 3, fail
		if len(subs) == 0 {
			logs.Err.Println("hub: missing both subscriptions for '" + t.name + "' (SHOULD NEVER HAPPEN!)")
			return types.ErrInternal
		}

		t.created = stopic.CreatedAt
		t.updated = stopic.UpdatedAt
		if !stopic.TouchedAt.IsZero() {
			t.touched = stopic.TouchedAt
		}
		t.aux = stopic.Aux
		t.lastID = stopic.SeqId
		t.delID = stopic.DelId
	}

	// t.owner is blank for p2p topics

	// Default user access to P2P topics is not set because it's unused.
	// Other users cannot join the topic because of how topic name is constructed.
	// The two participants set each other's access instead.
	// t.accessAuth = getDefaultAccess(t.cat, true)
	// t.accessAnon = getDefaultAccess(t.cat, false)

	// t.public and t.trusted are not used for p2p topics since each user get a different public/trusted.

	if stopic != nil && len(subs) == 2 {
		// Case 4.
		for i := range 2 {
			uid := types.ParseUid(subs[i].User)
			t.perUser[uid] = perUserData{