// discoverInstance will attempt discovering an instance (unless it is already up to date) and will
// list down its master and slaves (if any) for further discovery.
func discoverInstance(instanceKey inst.InstanceKey) {
start := time.Now()
instanceKey.Formalize()
if !instanceKey.IsValid() {
return
}
if existsInCacheError := recentDiscoveryOperationKeys.Add(instanceKey.DisplayString(), true, cache.DefaultExpiration); existsInCacheError != nil {
// Just recently attempted
return
}
instance, found, err := inst.ReadInstance(&instanceKey)
if found && instance.IsUpToDate && instance.IsLastCheckValid {
// we've already discovered this one. Skip!
return
}
discoveriesCounter.Inc(1)
// First we've ever heard of this instance. Continue investigation:
instance, err = inst.ReadTopologyInstance(&instanceKey)
// panic can occur (IO stuff). Therefore it may happen
// that instance is nil. Check it.
if instance == nil {
failedDiscoveriesCounter.Inc(1)
log.Warningf("discoverInstance(%+v) instance is nil in %.3fs, error=%+v", instanceKey, time.Since(start).Seconds(), err)
return
}
log.Debugf("Discovered host: %+v, master: %+v, version: %+v in %.3fs", instance.Key, instance.MasterKey, instance.Version, time.Since(start).Seconds())
if atomic.LoadInt64(&isElectedNode) == 0 {
// Maybe this node was elected before, but isn't elected anymore.
// If not elected, stop drilling up/down the topology
return
}
// Investigate slaves:
for _, slaveKey := range instance.SlaveHosts.GetInstanceKeys() {
slaveKey := slaveKey
if slaveKey.IsValid() {
discoveryQueue.Push(slaveKey)
}
}
// Investigate master:
if instance.MasterKey.IsValid() {
discoveryQueue.Push(instance.MasterKey)
}
}
// discoverInstance will attempt discovering an instance (unless it is already up to date) and will
// list down its master and slaves (if any) for further discovery.
func discoverInstance(instanceKey inst.InstanceKey) {
instanceKey.Formalize()
if !instanceKey.IsValid() {
return
}
if existsInCacheError := recentDiscoveryOperationKeys.Add(instanceKey.DisplayString(), true, cache.DefaultExpiration); existsInCacheError != nil {
// Just recently attempted
return
}
instance, found, err := inst.ReadInstance(&instanceKey)
if found && instance.IsUpToDate && instance.IsLastCheckValid {
// we've already discovered this one. Skip!
return
}
discoveriesCounter.Inc(1)
// First we've ever heard of this instance. Continue investigation:
instance, err = inst.ReadTopologyInstance(&instanceKey)
// panic can occur (IO stuff). Therefore it may happen
// that instance is nil. Check it.
if instance == nil {
failedDiscoveriesCounter.Inc(1)
log.Warningf("instance is nil in discoverInstance. key=%+v, error=%+v", instanceKey, err)
return
}
log.Debugf("Discovered host: %+v, master: %+v", instance.Key, instance.MasterKey)
if !isElectedNode {
// Maybe this node was elected before, but isn't elected anymore.
// If not elected, stop drilling down to further investigate slaves.
return
}
// Investigate slaves:
for _, slaveKey := range instance.SlaveHosts.GetInstanceKeys() {
discoveryInstanceKeys <- slaveKey
}
// Investigate master:
discoveryInstanceKeys <- instance.MasterKey
}