software.amazon.jdbc.hostlistprovider

Class ClusterTopologyMonitorImpl

java.lang.Object

software.amazon.jdbc.util.monitoring.AbstractMonitor

software.amazon.jdbc.hostlistprovider.ClusterTopologyMonitorImpl

All Implemented Interfaces:

java.lang.Runnable, ClusterTopologyMonitor, EventSubscriber, Monitor, StateSnapshotProvider

Direct Known Subclasses:

GlobalAuroraTopologyMonitor

public class ClusterTopologyMonitorImpl
extends AbstractMonitor
implements ClusterTopologyMonitor, StateSnapshotProvider

Field Summary

Fields

Modifier and Type	Field and Description
protected static int	closeConnectionNetworkTimeoutMs
protected java.lang.String	clusterId
protected java.util.Map<java.lang.String,java.lang.Boolean>	completedOneCycle
protected MonitoringConnectionHandler	connectionHandler
protected static int	defaultConnectionTimeoutMs
protected static int	defaultSocketTimeoutMs
protected java.util.concurrent.atomic.AtomicReference<java.sql.SQLException>	fatalError
protected static long	highRefreshPeriodAfterPanicNano
protected long	highRefreshRateEndTimeNano
protected long	highRefreshRateNano
protected java.util.function.Function<HostSpec,java.util.List<java.lang.Object>>	hostSpecExtractor
protected HostSpec	initialHostSpec
protected HostSpec	instanceTemplate
protected @Nullable HostSpec	lastKnownWriterHostSpec The last writer we believed to be the cluster's writer, retained even after writerHostSpec is cleared on errors.
protected boolean	logUnclosedConnections
protected static java.lang.String	MONITORING_PROPERTY_PREFIX
protected AtomicConnection	monitoringConnection
protected java.util.Properties	monitoringProperties
protected static long	monitorTerminationTimeoutSec
protected static java.util.concurrent.Executor	networkTimeoutExecutor
protected ResourceLock	nodeExecutorLock
protected @Nullable java.util.concurrent.ExecutorService	nodeExecutorService
protected java.util.concurrent.ConcurrentHashMap<HostSpec,AtomicConnection>	nodeThreadsConnections
protected java.util.concurrent.atomic.AtomicReference<java.util.List<HostSpec>>	nodeThreadsLatestTopology
protected java.util.concurrent.atomic.AtomicBoolean	nodeThreadsStop
protected java.util.concurrent.atomic.AtomicReference<HostSpec>	nodeThreadsWriterHostSpec
protected java.util.Properties	properties
protected static RdsUtils	rdsHelper
protected java.util.Map<java.lang.String,java.util.List<HostSpec>>	readerTopologiesById
protected long	refreshRateNano
protected java.util.concurrent.atomic.AtomicBoolean	requestToUpdateTopology
protected FullServicesContainer	servicesContainer
protected long	stableTopologiesStartNano
protected java.util.concurrent.ConcurrentHashMap<java.lang.String,java.lang.Boolean>	submittedNodes
protected java.lang.Object	topologyUpdated
protected TopologyUtils	topologyUtils
protected java.util.concurrent.atomic.AtomicReference<HostSpec>	writerHostSpec

Fields inherited from class software.amazon.jdbc.util.monitoring.AbstractMonitor

lastActivityTimestampNanos, monitorExecutor, state, stop, terminationTimeoutSec

Constructor Summary

Constructors

Constructor and Description
ClusterTopologyMonitorImpl(FullServicesContainer servicesContainer, TopologyUtils topologyUtils, java.lang.String clusterId, HostSpec initialHostSpec, java.util.Properties properties, HostSpec instanceTemplate, long refreshRateNano, long highRefreshRateNano)

Method Summary

Modifier and Type	Method and Description
boolean	canDispose() Defines whether this monitor can be disposed.
protected void	checkForStableReaderTopologies()
protected void	clearTopologyCache()
void	close() Closes all resources used by this monitor.
protected void	closeConnection(@Nullable java.sql.Connection connection)
protected void	closeNodeMonitors()
protected MonitoringConnectionHandler	createConnectionHandler()
protected void	createNodeExecutorService()
protected void	delay(boolean useHighRefreshRate)
protected @Nullable java.util.List<HostSpec>	fetchTopologyAndUpdateCache(@Nullable java.sql.Connection connection)
protected java.util.List<HostSpec>	filterHostsForNodeMonitoring(java.util.List<HostSpec> hosts) Filters the list of hosts that should be used for node monitoring during panic mode.
@Nullable java.util.List<HostSpec>	forceRefresh(boolean verifyTopology, long timeoutMs)
protected MonitoringConnectionHandler	getConnectionHandler() Returns the connection handler, creating it lazily on first access.
protected HostSpec	getInstanceTemplate(@Nullable java.lang.String nodeId, java.sql.Connection connection)
protected java.lang.Runnable	getNodeMonitoringWorker(HostSpec hostSpec, @Nullable HostSpec writerHostSpec, boolean someRegionsInaccessible)
java.util.List<Pair<java.lang.String,java.lang.Object>>	getSnapshotState()
protected long	getStableTopologiesDurationNano()
protected @Nullable java.util.List<HostSpec>	getStoredHosts()
protected boolean	isInPanicMode()
protected boolean	isUnresolvableDueToMisconfiguration(java.lang.Throwable t) Determines whether a connection failure is a permanent DNS-resolution failure caused by a configuration problem: the instance template is the bare "?" placeholder (built only when the connection host is not a recognized RDS endpoint and no clusterInstanceHostPattern was supplied), and the underlying cause is an UnknownHostException.
void	monitor() Executes the monitoring loop for this monitor.
protected void	nodeThreadConnectionCleanUp()
protected @Nullable java.util.List<HostSpec>	openAnyConnectionAndUpdateTopology()
void	processEvent(Event event) Processes an event.
protected @Nullable java.util.List<HostSpec>	queryForTopology(java.sql.Connection connection)
protected void	recordFatalError(java.sql.SQLException ex) Records a non-recoverable configuration error detected by a node monitor and wakes any threads waiting for a topology update so they can fail fast instead of blocking until the failover timeout.
protected void	reset()
void	stop() Stops the monitoring tasks for this monitor and closes all resources.
protected void	submitNodeMonitorIfAbsent(HostSpec hostSpec, @Nullable HostSpec baselineWriter, boolean someRegionsInaccessible, java.util.List<java.lang.Exception> exceptionList) Submits a node-monitoring worker for hostSpec unless one has already been submitted for that host.
protected void	throwIfFatalError() Throws the recorded fatal error, if any, so that a thread waiting for a topology update fails fast instead of blocking until the failover timeout.
protected void	updateHostsAvailability(@NonNull java.util.List<HostSpec> hosts)
protected void	updateTopologyCache(@NonNull java.util.List<HostSpec> hosts)
protected @Nullable java.util.List<HostSpec>	waitForTopologyUpdate(long timeoutMs)
protected void	wakeUpMonitoringLoop() Wakes up the monitoring loop so it can process events (e.g., a completed connection upgrade) immediately instead of waiting for the next refresh cycle.

Methods inherited from class software.amazon.jdbc.util.monitoring.AbstractMonitor

getLastActivityTimestampNanos, getState, run, start

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface software.amazon.jdbc.util.monitoring.Monitor

getLastActivityTimestampNanos, getState, start

Field Detail

MONITORING_PROPERTY_PREFIX

protected static final java.lang.String MONITORING_PROPERTY_PREFIX

See Also:

Constant Field Values

networkTimeoutExecutor

protected static final java.util.concurrent.Executor networkTimeoutExecutor

rdsHelper

protected static final RdsUtils rdsHelper

monitorTerminationTimeoutSec

protected static final long monitorTerminationTimeoutSec

See Also:

Constant Field Values

closeConnectionNetworkTimeoutMs

protected static final int closeConnectionNetworkTimeoutMs

See Also:

Constant Field Values

defaultConnectionTimeoutMs

protected static final int defaultConnectionTimeoutMs

See Also:

Constant Field Values

defaultSocketTimeoutMs

protected static final int defaultSocketTimeoutMs

See Also:

Constant Field Values

highRefreshPeriodAfterPanicNano

protected static final long highRefreshPeriodAfterPanicNano

writerHostSpec

protected final java.util.concurrent.atomic.AtomicReference<HostSpec> writerHostSpec

lastKnownWriterHostSpec

protected volatile @Nullable HostSpec lastKnownWriterHostSpec

The last writer we believed to be the cluster's writer, retained even after writerHostSpec is cleared on errors. Used by panic-mode node threads as a baseline for writer-change detection.

monitoringConnection

protected AtomicConnection monitoringConnection

topologyUpdated

protected final java.lang.Object topologyUpdated

requestToUpdateTopology

protected final java.util.concurrent.atomic.AtomicBoolean requestToUpdateTopology

submittedNodes

protected final java.util.concurrent.ConcurrentHashMap<java.lang.String,java.lang.Boolean> submittedNodes

fatalError

protected final java.util.concurrent.atomic.AtomicReference<java.sql.SQLException> fatalError

nodeExecutorLock

protected final ResourceLock nodeExecutorLock

nodeThreadsStop

protected final java.util.concurrent.atomic.AtomicBoolean nodeThreadsStop

nodeThreadsWriterHostSpec

protected final java.util.concurrent.atomic.AtomicReference<HostSpec> nodeThreadsWriterHostSpec

nodeThreadsLatestTopology

protected final java.util.concurrent.atomic.AtomicReference<java.util.List<HostSpec>> nodeThreadsLatestTopology

nodeThreadsConnections

protected final java.util.concurrent.ConcurrentHashMap<HostSpec,AtomicConnection> nodeThreadsConnections

readerTopologiesById

protected final java.util.Map<java.lang.String,java.util.List<HostSpec>> readerTopologiesById

completedOneCycle

protected final java.util.Map<java.lang.String,java.lang.Boolean> completedOneCycle

stableTopologiesStartNano

protected long stableTopologiesStartNano

hostSpecExtractor

protected java.util.function.Function<HostSpec,java.util.List<java.lang.Object>> hostSpecExtractor

refreshRateNano

protected final long refreshRateNano

highRefreshRateNano

protected final long highRefreshRateNano

topologyUtils

protected final TopologyUtils topologyUtils

servicesContainer

protected final FullServicesContainer servicesContainer

properties

protected final java.util.Properties properties

monitoringProperties

protected final java.util.Properties monitoringProperties

initialHostSpec

protected final HostSpec initialHostSpec

instanceTemplate

protected final HostSpec instanceTemplate

nodeExecutorService

protected @Nullable java.util.concurrent.ExecutorService nodeExecutorService

highRefreshRateEndTimeNano

protected long highRefreshRateEndTimeNano

clusterId

protected java.lang.String clusterId

logUnclosedConnections

protected boolean logUnclosedConnections

connectionHandler

protected MonitoringConnectionHandler connectionHandler

Constructor Detail

ClusterTopologyMonitorImpl

public ClusterTopologyMonitorImpl(FullServicesContainer servicesContainer,
                                  TopologyUtils topologyUtils,
                                  java.lang.String clusterId,
                                  HostSpec initialHostSpec,
                                  java.util.Properties properties,
                                  HostSpec instanceTemplate,
                                  long refreshRateNano,
                                  long highRefreshRateNano)

Method Detail

getConnectionHandler

protected MonitoringConnectionHandler getConnectionHandler()

Returns the connection handler, creating it lazily on first access. Lazy initialization is required so that subclass state (e.g., shadowed fields) is fully initialized before createConnectionHandler() is invoked.

canDispose

public boolean canDispose()

Description copied from interface: Monitor

Defines whether this monitor can be disposed.

Specified by:

canDispose in interface ClusterTopologyMonitor

Specified by:

canDispose in interface Monitor

Overrides:

canDispose in class AbstractMonitor

Returns:

true if this monitor can be disposed, otherwise returns false.

forceRefresh

public @Nullable java.util.List<HostSpec> forceRefresh(boolean verifyTopology,
                                                       long timeoutMs)
                                                throws java.sql.SQLException,
                                                       java.util.concurrent.TimeoutException

Specified by:

forceRefresh in interface ClusterTopologyMonitor

Throws:

java.sql.SQLException

java.util.concurrent.TimeoutException

waitForTopologyUpdate

protected @Nullable java.util.List<HostSpec> waitForTopologyUpdate(long timeoutMs)
                                                            throws java.util.concurrent.TimeoutException,
                                                                   java.sql.SQLException

Throws:

java.util.concurrent.TimeoutException

java.sql.SQLException

throwIfFatalError

protected void throwIfFatalError()
                          throws java.sql.SQLException

Throws the recorded fatal error, if any, so that a thread waiting for a topology update fails fast instead of blocking until the failover timeout. Used for non-recoverable configuration problems. A new exception instance is thrown so the stack trace reflects the waiting thread while the original message, SQL state, and cause are preserved.

Throws:

java.sql.SQLException

recordFatalError

protected void recordFatalError(java.sql.SQLException ex)

Records a non-recoverable configuration error detected by a node monitor and wakes any threads waiting for a topology update so they can fail fast instead of blocking until the failover timeout.

isUnresolvableDueToMisconfiguration

protected boolean isUnresolvableDueToMisconfiguration(java.lang.Throwable t)

Determines whether a connection failure is a permanent DNS-resolution failure caused by a configuration problem: the instance template is the bare "?" placeholder (built only when the connection host is not a recognized RDS endpoint and no clusterInstanceHostPattern was supplied), and the underlying cause is an UnknownHostException. In that case the derived instance endpoints can never resolve, so retrying until the failover timeout is pointless.

getStoredHosts

protected @Nullable java.util.List<HostSpec> getStoredHosts()

stop

public void stop()

Description copied from interface: Monitor

Stops the monitoring tasks for this monitor and closes all resources.

Specified by:

stop in interface Monitor

Overrides:

stop in class AbstractMonitor

close

public void close()

Description copied from interface: Monitor

Closes all resources used by this monitor. This method will be called as part of Monitor.stop().

Specified by:

close in interface Monitor

Overrides:

close in class AbstractMonitor

monitor

public void monitor()
             throws java.lang.Exception

Description copied from interface: Monitor

Executes the monitoring loop for this monitor. This method should be called in the run() method of the thread submitted during the call to Monitor.start(). Additionally, the monitoring loop should regularly update the last activity timestamp so that the MonitorService can detect whether the monitor is stuck or not.

Specified by:

monitor in interface Monitor

Throws:

java.lang.Exception - if there's an error executing the monitoring logic.

checkForStableReaderTopologies

protected void checkForStableReaderTopologies()

reset

protected void reset()

processEvent

public void processEvent(Event event)

Description copied from interface: EventSubscriber

Processes an event. This method will only be called on this subscriber if it has subscribed to the event class via EventPublisher.subscribe(software.amazon.jdbc.util.events.EventSubscriber, java.util.Set<java.lang.Class<? extends software.amazon.jdbc.util.events.Event>>).

Specified by:

processEvent in interface EventSubscriber

Parameters:

event - the event to process.

nodeThreadConnectionCleanUp

protected void nodeThreadConnectionCleanUp()

closeNodeMonitors

protected void closeNodeMonitors()

createNodeExecutorService

protected void createNodeExecutorService()

createConnectionHandler

protected MonitoringConnectionHandler createConnectionHandler()

wakeUpMonitoringLoop

protected void wakeUpMonitoringLoop()

Wakes up the monitoring loop so it can process events (e.g., a completed connection upgrade) immediately instead of waiting for the next refresh cycle.

isInPanicMode

protected boolean isInPanicMode()

filterHostsForNodeMonitoring

protected java.util.List<HostSpec> filterHostsForNodeMonitoring(java.util.List<HostSpec> hosts)

Filters the list of hosts that should be used for node monitoring during panic mode. Subclasses can override this to restrict which hosts are eligible for connection attempts.

Parameters:

hosts - the full list of hosts from the topology

Returns:

the filtered list of hosts to use for node monitoring

submitNodeMonitorIfAbsent

protected void submitNodeMonitorIfAbsent(HostSpec hostSpec,
                                         @Nullable HostSpec baselineWriter,
                                         boolean someRegionsInaccessible,
                                         java.util.List<java.lang.Exception> exceptionList)

Submits a node-monitoring worker for hostSpec unless one has already been submitted for that host. Any SQLException raised while creating the worker is collected into exceptionList and the host is left unsubmitted so it can be retried on a later cycle.

getNodeMonitoringWorker

protected java.lang.Runnable getNodeMonitoringWorker(HostSpec hostSpec,
                                                     @Nullable HostSpec writerHostSpec,
                                                     boolean someRegionsInaccessible)
                                              throws java.sql.SQLException

Throws:

java.sql.SQLException

openAnyConnectionAndUpdateTopology

protected @Nullable java.util.List<HostSpec> openAnyConnectionAndUpdateTopology()

getInstanceTemplate

protected HostSpec getInstanceTemplate(@Nullable java.lang.String nodeId,
                                       java.sql.Connection connection)
                                throws java.sql.SQLException

Throws:

java.sql.SQLException

closeConnection

protected void closeConnection(@Nullable java.sql.Connection connection)

delay

protected void delay(boolean useHighRefreshRate)
              throws java.lang.InterruptedException

Throws:

java.lang.InterruptedException

fetchTopologyAndUpdateCache

protected @Nullable java.util.List<HostSpec> fetchTopologyAndUpdateCache(@Nullable java.sql.Connection connection)

queryForTopology

protected @Nullable java.util.List<HostSpec> queryForTopology(java.sql.Connection connection)
                                                       throws java.sql.SQLException

Throws:

java.sql.SQLException

updateHostsAvailability

protected void updateHostsAvailability(@NonNull java.util.List<HostSpec> hosts)

updateTopologyCache

protected void updateTopologyCache(@NonNull java.util.List<HostSpec> hosts)

clearTopologyCache

protected void clearTopologyCache()

getStableTopologiesDurationNano

protected long getStableTopologiesDurationNano()

getSnapshotState

public java.util.List<Pair<java.lang.String,java.lang.Object>> getSnapshotState()

Specified by:

getSnapshotState in interface StateSnapshotProvider