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
}
//Adjust the size of the prepared statements cache to match the latest configuration
stmtsLRU.Lock()
initStmtsLRU(cfg.MaxPreparedStmts)
stmtsLRU.Unlock()
s := &Session{
cons: cfg.Consistency,
prefetch: 0.25,
cfg: cfg,
pageSize: cfg.PageSize,
}
pool, err := cfg.PoolConfig.buildPool(s)
if err != nil {
return nil, err
}
s.pool = pool
// See if there are any connections in the pool
if pool.Size() == 0 {
s.Close()
return nil, ErrNoConnectionsStarted
}
s.routingKeyInfoCache.lru = lru.New(cfg.MaxRoutingKeyInfo)
// I think it might be a good idea to simplify this and make it always discover
// hosts, maybe with more filters.
if cfg.DiscoverHosts {
s.hostSource = &ringDescriber{
session: s,
dcFilter: cfg.Discovery.DcFilter,
rackFilter: cfg.Discovery.RackFilter,
closeChan: make(chan bool),
}
}
if !cfg.disableControlConn {
s.control = createControlConn(s)
s.control.reconnect(false)
// need to setup host source to check for rpc_address in system.local
localHasRPCAddr, err := checkSystemLocal(s.control)
if err != nil {
log.Printf("gocql: unable to verify if system.local table contains rpc_address, falling back to connection address: %v", err)
}
if cfg.DiscoverHosts {
s.hostSource.localHasRpcAddr = localHasRPCAddr
}
}
if cfg.DiscoverHosts {
s.hostSource.refreshRing()
go s.hostSource.run(cfg.Discovery.Sleep)
}
return s, nil
}