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package pb
import (
"github.com/seaweedfs/seaweedfs/weed/glog"
"reflect"
)
// ServerDiscovery encodes a way to find at least 1 instance of a service,
// and provides utility functions to refresh the instance list
type ServerDiscovery struct {
list []ServerAddress
srvRecord *ServerSrvAddress
}
func NewServiceDiscoveryFromMap(m map[string]ServerAddress) (sd *ServerDiscovery) {
sd = &ServerDiscovery{}
for _, s := range m {
sd.list = append(sd.list, s)
}
return sd
}
// RefreshBySrvIfAvailable performs a DNS SRV lookup and updates list with the results
// of the lookup
func (sd *ServerDiscovery) RefreshBySrvIfAvailable() {
if sd.srvRecord == nil {
return
}
newList, err := sd.srvRecord.LookUp()
if err != nil {
glog.V(0).Infof("failed to lookup SRV for %s: %v", *sd.srvRecord, err)
}
if newList == nil || len(newList) == 0 {
glog.V(0).Infof("looked up SRV for %s, but found no well-formed names", *sd.srvRecord)
return
}
if !reflect.DeepEqual(sd.list, newList) {
sd.list = newList
}
}
// GetInstances returns a copy of the latest known list of addresses
// call RefreshBySrvIfAvailable prior to this in order to get a more up-to-date view
func (sd *ServerDiscovery) GetInstances() (addresses []ServerAddress) {
for _, a := range sd.list {
addresses = append(addresses, a)
}
return addresses
}
func (sd *ServerDiscovery) GetInstancesAsStrings() (addresses []string) {
for _, i := range sd.list {
addresses = append(addresses, string(i))
}
return addresses
}
func (sd *ServerDiscovery) GetInstancesAsMap() (addresses map[string]ServerAddress) {
addresses = make(map[string]ServerAddress)
for _, i := range sd.list {
addresses[string(i)] = i
}
return addresses
}
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