race-conditions in service.go and session.go

[shamork]

every operation of *Session.Cmsg in session.go is like this

this.mu.Lock()
defer this.mu.Unlock()
blabla~~~

but in service.go line 237-241

// Publish will message if WillFlag is set. Server side only.
if !this.client && this.sess.Cmsg.WillFlag() {
glog.Infof("(%s) service/stop: connection unexpectedly closed. Sending Will.", this.cid())
this.onPublish(this.sess.Will)
}

there is no lock when operating this.sess.Cmsg

My opinion is:

1. make Session.Cmsg private
2. adding the lines below to session.go, and using the functions instead of this.sess.Cmsg
3. if possible, change this.mu from sync.Mutex to sync.RWMutex

func (this *Session) WillFlag() bool {
this.mu.Lock()
defer this.mu.Unlock()
return this.cmsg.WillFlag()
}

func (this *Session) SetWillFlag(v bool) {
this.mu.Lock()
defer this.mu.Unlock()
this.cmsg.SetWillFlag(v)
}

func (this *Session) CleanSession() bool {
this.mu.Lock()
defer this.mu.Unlock()
return this.cmsg.CleanSession()
}

Another place of this problem in memtopics.go line 128-130

func (this *memTopics) Close() error {
this.sroot = nil
this.rroot = nil
return nil
}

shoud change to

func (this *memTopics) Close() error {
this.smu.Lock()
this.sroot = nil
this.smu.Unlock()
this.rmu.Lock()
this.rroot = nil
this.rmu.Unlock()
}

I'll Pull Request later when I complete my coding