func (t *Topic) makeInvite(notify, target, from types.Uid, act types.InviteAction, modeWant,
	modeGiven types.AccessMode, info interface{}) *ServerComMessage {

	// FIXME(gene): this is a workaround for gorethink's broken way of marshalling json
	inv, err := json.Marshal(MsgInvitation{
		Topic:  t.name,
		User:   target.UserId(),
		Action: act.String(),
		Acs:    MsgAccessMode{modeWant.String(), modeGiven.String()},
		Info:   info})
	if err != nil {
		log.Println(err)
	}
	converted := map[string]interface{}{}
	err = json.Unmarshal(inv, &converted)
	if err != nil {
		log.Println(err)
	}
	// endof workaround

	msg := &ServerComMessage{Data: &MsgServerData{
		Topic:     "me",
		From:      from.UserId(),
		Timestamp: time.Now().UTC().Round(time.Millisecond),
		Content:   converted}, rcptto: notify.UserId()}
	log.Printf("Invite generated: %#+v", msg.Data)
	return msg
}

// approveSub processes a request to initiate an invite or approve a subscription request from another user:
// Handle these cases:
// A. Manager is inviting another user for the first time (no prior subscription)
// B. Manager is re-inviting another user (adjusting modeGiven, modeWant is still "N")
// C. Manager is changing modeGiven for another user, modeWant != "N"
func (t *Topic) approveSub(h *Hub, sess *Session, target types.Uid, set *MsgClientSet) error {
	now := time.Now().UTC().Round(time.Millisecond)

	// Check if requester actually has permission to manage sharing
	if userData, ok := t.perUser[sess.uid]; !ok || !userData.modeGiven.IsManager() || !userData.modeWant.IsManager() {
		sess.queueOut(ErrPermissionDenied(set.Id, t.original, now))
		return errors.New("topic access denied")
	}

	// Parse the access mode granted
	var modeGiven types.AccessMode
	if set.Sub.Mode != "" {
		modeGiven.UnmarshalText([]byte(set.Sub.Mode))
	}

	// If the user is banned from topic, make sute it's the only change
	if modeGiven.IsBanned() {
		modeGiven = types.ModeBanned
	}

	// Make sure no one but the owner can do an ownership transfer
	if modeGiven.IsOwner() && t.owner != sess.uid {
		sess.queueOut(ErrPermissionDenied(set.Id, t.original, now))
		return errors.New("attempt to transfer ownership by non-owner")
	}

	var givenBefore types.AccessMode
	// Check if it's a new invite. If so, save it to database as a subscription.
	// Saved subscription does not mean the user is allowed to post/read
	userData, ok := t.perUser[target]
	if !ok {
		if modeGiven == types.ModeNone {
			if t.accessAuth != types.ModeNone {
				// Request to use default access mode for the new subscriptions.
				modeGiven = t.accessAuth
			} else {
				sess.queueOut(ErrMalformed(set.Id, t.original, now))
				return errors.New("cannot invite without giving any access rights")
			}
		}

		// Add subscription to database
		sub := &types.Subscription{
			User:      target.String(),
			Topic:     t.name,
			ModeWant:  types.ModeNone,
			ModeGiven: modeGiven,
		}

		if err := store.Subs.Create(sub); err != nil {
			sess.queueOut(ErrUnknown(set.Id, t.original, now))
			return err
		}

		userData = perUserData{
			modeGiven: sub.ModeGiven,
			modeWant:  sub.ModeWant,
			private:   nil,
		}

		t.perUser[target] = userData

	} else {
		// Action on an existing subscription (re-invite or confirm/decline)
		givenBefore = userData.modeGiven

		// Request to re-send invite without changing the access mode
		if modeGiven == types.ModeNone {
			modeGiven = userData.modeGiven
		} else if modeGiven != userData.modeGiven {
			userData.modeGiven = modeGiven

			// Save changed value to database
			if err := store.Subs.Update(t.name, sess.uid,
				map[string]interface{}{"ModeGiven": modeGiven}); err != nil {
				return err
			}

			t.perUser[target] = userData
		}
	}

	// The user does not want to be bothered, no further action is needed
	if userData.modeWant.IsBanned() {
		sess.queueOut(ErrPermissionDenied(set.Id, t.original, now))
		return errors.New("topic access denied")
	}

	// Handle the following cases:
	// * a ban of the user, modeGive.IsBanned = true (if user is banned no need to invite anyone)
	// * regular invite: modeWant = "N", modeGiven > 0
	// * access rights update: old modeGiven != new modeGiven
	if !modeGiven.IsBanned() {
		if userData.modeWant == types.ModeNone {
			// (re-)Send the invite to target
//.........这里部分代码省略.........

// User requests or updates a self-subscription to a topic
//	h 		- hub
//	sess 	- originating session
//  pktId 	- originating packet Id
//	want	- requested access mode
//	info 	- explanation info given by the requester
//	private	- private value to assign to the subscription
// Handle these cases:
// A. User is trying to subscribe for the first time (no subscription)
// B. User is already subscribed, just joining without changing anything
// C. User is responsing to an earlier invite (modeWant was "N" in subscription)
// D. User is already subscribed, changing modeWant
// E. User is accepting ownership transfer (requesting ownership transfer is not permitted)
func (t *Topic) requestSub(h *Hub, sess *Session, pktId string, want string, info,
	private interface{}, loaded bool) error {

	log.Println("requestSub", t.name)

	now := time.Now().UTC().Round(time.Millisecond)

	// Parse the acess mode requested by the user
	var modeWant types.AccessMode
	var explicitWant bool
	if want != "" {
		log.Println("mode want explicit: ", want)
		modeWant.UnmarshalText([]byte(want))
		explicitWant = true
	}

	// If the user wants a self-ban, make sure it's the only change
	if modeWant.IsBanned() {
		modeWant = types.ModeBanned
	}

	// Vars for saving changes to access mode
	var updWant *types.AccessMode
	var updGiven *types.AccessMode

	// Check if it's an attempt at a new subscription to the topic. If so, save it to database
	userData, existingSub := t.perUser[sess.uid]
	if !existingSub {
		// User requested default access mode.
		// modeWant could still be ModeNone if the owner wants to manually approve every request
		if modeWant == types.ModeNone {
			if explicitWant {
				// The operation is invalid - user requested to clear access to topic which makes no sense.
				sess.queueOut(ErrMalformed(pktId, t.original, now))
				return errors.New("attempt to clear topic access")
			}

			modeWant = t.accessAuth
		}

		userData = perUserData{
			private:   private,
			modeGiven: t.accessAuth,
			modeWant:  modeWant,
		}

		// If it's a re-subscription to a p2p topic, set public
		if t.cat == types.TopicCat_P2P {
			// t.perUser contains just one element - other user
			for uid2, _ := range t.perUser {
				if user2, err := store.Users.Get(uid2); err != nil {
					log.Println(err.Error())
					sess.queueOut(ErrUnknown(pktId, t.original, now))
					return err
				} else {
					userData.public = user2.Public
				}
				break
			}
		}

		// Add subscription to database
		sub := &types.Subscription{
			User:      sess.uid.String(),
			Topic:     t.name,
			ModeWant:  userData.modeWant,
			ModeGiven: userData.modeGiven,
			Private:   userData.private,
		}

		if err := store.Subs.Create(sub); err != nil {
			log.Println(err.Error())
			sess.queueOut(ErrUnknown(pktId, t.original, now))
			return err
		}

	} else {
		var ownerChange bool
		// Process update to existing subscription. It could be an incomplete subscription for a new topic.

		// If user did not request a new access mode, copy one from cache
		if !explicitWant && modeWant == types.ModeNone {
			modeWant = userData.modeWant
		}

		if userData.modeGiven.IsOwner() {
			// Check for possible ownership transfer. Handle the following cases:
//.........这里部分代码省略.........

//.........这里部分代码省略.........
	for _, ss := range data.Subscriptions {
		u1 := ss["user"].(string)
		u2 := ss["topic"].(string)

		if u2[0] == '*' {
			// skip group topics
			continue
		}

		var pair string
		var idx int
		if u1 < u2 {
			pair = u1 + ":" + u2
			idx = 0
		} else {
			pair = u2 + ":" + u1
			idx = 1
		}
		if _, ok := p2pIndex[pair]; !ok {
			p2pIndex[pair] = make([]map[string]interface{}, 2)
		}

		p2pIndex[pair][idx] = ss
	}

	log.Printf("Collected p2p pairs: %d\n", len(p2pIndex))

	for pair, subs := range p2pIndex {
		uid1 := types.ParseUid(nameIndex[subs[0]["user"].(string)])
		uid2 := types.ParseUid(nameIndex[subs[1]["user"].(string)])
		topic := uid1.P2PName(uid2)
		created0 := getCreatedTime(subs[0]["createdAt"])
		created1 := getCreatedTime(subs[1]["createdAt"])
		var s0want, s0given, s1want, s1given types.AccessMode
		if err := s0want.UnmarshalText([]byte(subs[0]["modeWant"].(string))); err != nil {
			log.Fatal(err)
		}
		if err := s0given.UnmarshalText([]byte(subs[0]["modeHave"].(string))); err != nil {
			log.Fatal(err)
		}

		if err := s1want.UnmarshalText([]byte(subs[1]["modeWant"].(string))); err != nil {
			log.Fatal(err)
		}
		if err := s1given.UnmarshalText([]byte(subs[1]["modeHave"].(string))); err != nil {
			log.Fatal(err)
		}

		log.Printf("Processing %s (%s), %s, %s", pair, topic, uid1.String(), uid2.String())
		err := store.Topics.CreateP2P(
			&types.Subscription{
				ObjHeader: types.ObjHeader{CreatedAt: created0},
				User:      uid1.String(),
				Topic:     topic,
				ModeWant:  s0want,
				ModeGiven: s0given,
				Private:   subs[0]["private"]},
			&types.Subscription{
				ObjHeader: types.ObjHeader{CreatedAt: created1},
				User:      uid2.String(),
				Topic:     topic,
				ModeWant:  s1want,
				ModeGiven: s1given,
				Private:   subs[1]["private"]})

		if err != nil {