func initStmtsLRU(max int) {
if stmtsLRU.lru != nil {
stmtsLRU.Max(max)
} else {
stmtsLRU.lru = lru.New(max)
}
}
// NewSession wraps an existing Node.
func NewSession(cfg ClusterConfig) (*Session, error) {
//Check that hosts in the ClusterConfig is not empty
if len(cfg.Hosts) < 1 {
return nil, ErrNoHosts
}
maxStreams := 128
if cfg.ProtoVersion > protoVersion2 {
maxStreams = 32768
}
if cfg.NumStreams <= 0 || cfg.NumStreams > maxStreams {
cfg.NumStreams = maxStreams
}
pool, err := cfg.ConnPoolType(&cfg)
if err != nil {
return nil, err
}
//Adjust the size of the prepared statements cache to match the latest configuration
stmtsLRU.Lock()
initStmtsLRU(cfg.MaxPreparedStmts)
stmtsLRU.Unlock()
s := &Session{
Pool: pool,
cons: cfg.Consistency,
prefetch: 0.25,
cfg: cfg,
}
//See if there are any connections in the pool
if pool.Size() > 0 {
s.routingKeyInfoCache.lru = lru.New(cfg.MaxRoutingKeyInfo)
s.SetConsistency(cfg.Consistency)
s.SetPageSize(cfg.PageSize)
if cfg.DiscoverHosts {
s.hostSource = &ringDescriber{
session: s,
dcFilter: cfg.Discovery.DcFilter,
rackFilter: cfg.Discovery.RackFilter,
closeChan: make(chan bool),
}
go s.hostSource.run(cfg.Discovery.Sleep)
}
return s, nil
}
s.Close()
return nil, ErrNoConnectionsStarted
}