Process Startup / Join

// LeadSetGet provides a sample implementation of the GMLeaderSetterGetter
// interface in order to support persistence of the current group-leader
// information.  re-implement these methods as you see fit to facilitate
// storage and retrieval of the leader information to and from the persistent
// storage.  This example uses a quick and dirty web-socket-based cache to
// handle the persistence.  It works well enough for testing, but you should
// use something more robust like a database, redis etc.  The methods in the
// GMLeaderSetterGetter interface are called when a new process is attempting
// to join the group and also when a new leader is selected via the coordinator
// process.
//
// To test with the delivered interface implementation, install and run sluggo:
// go get -u github.com/1414C/sluggo
//
// Execute sluggo from the command-line as follows:
// go run main.go -a <ipaddress:port>
// For example:
// $ go run main.go -a 192.168.1.40:7070
//
type LeadSetGet struct {
  gmcom.GMLeaderSetterGetter
}

// GetDBLeader retrieves the current leader information from
// the persistence layer.
func (sg *LeadSetGet) GetDBLeader() (*gmcom.GMLeader, error) {

  // access the database here to read the current leader
  l := &gmcom.GMLeader{}
  wscl.GetCacheEntry("LEADER", l, "192.168.1.40:7070")
  return l, nil
}

// SetDBLeader stores the current leader information in the
// persistence layer.
func (sg *LeadSetGet) SetDBLeader(l gmcom.GMLeader) error {

  // access the database here to set a new current leader
  wscl.AddUpdCacheEntry("LEADER", &l, "192.168.1.40:7070")
  return nil
}

// Cleanup closes connections to group-leadership KVS when
// prior to application shutdown.
func (sg *LeadSetGet) Cleanup() error {
  
  // perform cleanup(s)
  return nil
}