// ContinuousDiscovery starts an asynchronuous infinite discovery process where instances are
// periodically investigated and their status captured, and long since unseen instances are
// purged and forgotten.
func ContinuousDiscovery() {
if config.Config.DatabaselessMode__experimental {
log.Fatal("Cannot execute continuous mode in databaseless mode")
}
log.Infof("Starting continuous discovery")
inst.LoadHostnameResolveCacheFromDatabase()
go handleDiscoveryRequests(nil, nil)
discoveryTick := time.Tick(time.Duration(config.Config.DiscoveryPollSeconds) * time.Second)
caretakingTick := time.Tick(time.Minute)
recoveryTick := time.Tick(time.Duration(config.Config.RecoveryPollSeconds) * time.Second)
var snapshotTopologiesTick <-chan time.Time
if config.Config.SnapshotTopologiesIntervalHours > 0 {
snapshotTopologiesTick = time.Tick(time.Duration(config.Config.SnapshotTopologiesIntervalHours) * time.Hour)
}
go ometrics.InitGraphiteMetrics()
go acceptSignals()
for {
select {
case <-discoveryTick:
go func() {
wasAlreadyElected := isElectedNode
if isElectedNode, _ = process.AttemptElection(); isElectedNode {
instanceKeys, _ := inst.ReadOutdatedInstanceKeys()
log.Debugf("outdated keys: %+v", instanceKeys)
for _, instanceKey := range instanceKeys {
discoveryInstanceKeys <- instanceKey
}
if !wasAlreadyElected {
// Just turned to be leader!
go process.HealthTest()
}
} else {
log.Debugf("Not elected as active node; polling")
}
}()
case <-caretakingTick:
// Various periodic internal maintenance tasks
go func() {
if isElectedNode {
go inst.ForgetLongUnseenInstances()
go inst.ForgetUnseenInstancesDifferentlyResolved()
go inst.ForgetExpiredHostnameResolves()
go inst.DeleteInvalidHostnameResolves()
go inst.ReviewUnseenInstances()
go inst.InjectUnseenMasters()
go inst.ResolveUnknownMasterHostnameResolves()
go inst.UpdateClusterAliases()
go inst.ExpireMaintenance()
go inst.ExpireDowntime()
go inst.ExpireCandidateInstances()
go inst.ExpireHostnameUnresolve()
go inst.ExpireClusterDomainName()
go inst.ExpireAudit()
go inst.ExpireMasterPositionEquivalence()
go inst.FlushNontrivialResolveCacheToDatabase()
}
if !isElectedNode {
// Take this opportunity to refresh yourself
inst.LoadHostnameResolveCacheFromDatabase()
}
go inst.ReadClusterAliases()
go process.HealthTest()
}()
case <-recoveryTick:
go func() {
if isElectedNode {
go ClearActiveFailureDetections()
go ClearActiveRecoveries()
go ExpireBlockedRecoveries()
go CheckAndRecover(nil, nil, false)
}
}()
case <-snapshotTopologiesTick:
go func() {
go inst.SnapshotTopologies()
}()
}
}
}
// 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
}
instance, found, err := inst.ReadInstance(&instanceKey)
if found && instance.IsUpToDate && instance.IsLastCheckValid {
// we've already discovered this one. Skip!
goto Cleanup
}
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 err != nil || instance == nil {
failedDiscoveriesCounter.Inc(1)
log.Warningf("instance is nil in discoverInstance. key=%+v, error=%+v", instanceKey, err)
goto Cleanup
}
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
Cleanup:
}
// Start discovery begins a one time asynchronuous discovery process for the given
// instance and all of its topology connected instances.
// That is, the instance will be investigated for master and slaves, and the routines will follow on
// each and every such found master/slave.
// In essense, assuming all slaves in a replication topology are running, and given a single instance
// in such topology, this function will detect the entire topology.
func StartDiscovery(instanceKey inst.InstanceKey) {
log.Infof("Starting discovery at %+v", instanceKey)
pendingTokens := make(chan bool, maxConcurrency)
completedTokens := make(chan bool, maxConcurrency)
accountedDiscoverInstance(instanceKey, pendingTokens, completedTokens)
go handleDiscoveryRequests(pendingTokens, completedTokens)
// Block until all are complete
for {
select {
case <-pendingTokens:
<-completedTokens
default:
inst.AuditOperation("start-discovery", &instanceKey, "")
return
}
}
}
// ContinuousDiscovery starts an asynchronuous infinite discovery process where instances are
// periodically investigated and their status captured, and long since unseen instances are
// purged and forgotten.
func ContinuousDiscovery() {
log.Infof("Starting continuous discovery")
inst.LoadHostnameResolveCacheFromDatabase()
go handleDiscoveryRequests(nil, nil)
tick := time.Tick(time.Duration(config.Config.DiscoveryPollSeconds) * time.Second)
forgetUnseenTick := time.Tick(time.Minute)
recoverTick := time.Tick(10 * time.Second)
var snapshotTopologiesTick <-chan time.Time
if config.Config.SnapshotTopologiesIntervalHours > 0 {
snapshotTopologiesTick = time.Tick(time.Duration(config.Config.SnapshotTopologiesIntervalHours) * time.Hour)
}
go ometrics.InitGraphiteMetrics()
for {
select {
case <-tick:
go func() {
if isElectedNode, _ = process.AttemptElection(); isElectedNode {
instanceKeys, _ := inst.ReadOutdatedInstanceKeys()
log.Debugf("outdated keys: %+v", instanceKeys)
for _, instanceKey := range instanceKeys {
discoveryInstanceKeys <- instanceKey
}
} else {
log.Debugf("Not elected as active node; polling")
}
}()
case <-forgetUnseenTick:
// See if we should also forget objects (lower frequency)
go func() {
if isElectedNode {
go inst.ForgetLongUnseenInstances()
go inst.ForgetUnseenInstancesDifferentlyResolved()
go inst.ForgetExpiredHostnameResolves()
go inst.DeleteInvalidHostnameResolves()
go inst.ReviewUnseenInstances()
go inst.InjectUnseenMasters()
go inst.ResolveUnknownMasterHostnameResolves()
go inst.UpdateClusterAliases()
go inst.ExpireMaintenance()
go inst.ExpireDowntime()
go inst.ExpireCandidateInstances()
go inst.ExpireHostnameUnresolve()
go inst.ExpireClusterDomainName()
go inst.ExpireAudit()
go inst.ExpireMasterPositionEquivalence()
go inst.FlushNontrivialResolveCacheToDatabase()
}
if !isElectedNode {
// Take this opportunity to refresh yourself
inst.LoadHostnameResolveCacheFromDatabase()
}
go inst.ReadClusterAliases()
go process.HealthTest()
}()
case <-recoverTick:
go func() {
if isElectedNode {
go ClearActiveFailureDetections()
go ClearActiveRecoveries()
go CheckAndRecover(nil, nil, false, false)
}
}()
case <-snapshotTopologiesTick:
go func() {
go inst.SnapshotTopologies()
}()
}
}
}
func pollAgent(hostname string) error {
polledAgent, err := agent.GetAgent(hostname)
agent.UpdateAgentLastChecked(hostname)
if err != nil {
return log.Errore(err)
}
err = agent.UpdateAgentInfo(hostname, polledAgent)
if err != nil {
return log.Errore(err)
}
return nil
}
// ContinuousAgentsPoll starts an asynchronuous infinite process where agents are
// periodically investigated and their status captured, and long since unseen agents are
// purged and forgotten.
func ContinuousAgentsPoll() {
log.Infof("Starting continuous agents poll")
go discoverSeededAgents()
tick := time.Tick(time.Duration(config.Config.DiscoveryPollSeconds) * time.Second)
forgetUnseenTick := time.Tick(time.Hour)
for range tick {
agentsHosts, _ := agent.ReadOutdatedAgentsHosts()
log.Debugf("outdated agents hosts: %+v", agentsHosts)
for _, hostname := range agentsHosts {
go pollAgent(hostname)
}
// See if we should also forget agents (lower frequency)
select {
case <-forgetUnseenTick:
agent.ForgetLongUnseenAgents()
agent.FailStaleSeeds()
default:
}
}
}
func discoverSeededAgents() {
for seededAgent := range agent.SeededAgents {
instanceKey := inst.InstanceKey{Hostname: seededAgent.Hostname, Port: int(seededAgent.MySQLPort)}
go StartDiscovery(instanceKey)
}
}