software.aws.rds.jdbc.postgresql.ca

Class AuroraTopologyService

java.lang.Object

software.aws.rds.jdbc.postgresql.ca.AuroraTopologyService

All Implemented Interfaces:

TopologyService

public class AuroraTopologyService
extends Object
implements TopologyService

An implementation of TopologyService created for Amazon Aurora

Field Summary

Fields

Modifier and Type	Field and Description
protected String	clusterId
protected HostInfo	clusterInstanceTemplate
protected boolean	gatherPerfMetrics
protected @MonotonicNonNull ClusterAwareMetrics	metrics
protected static ExpiringCache<String,software.aws.rds.jdbc.postgresql.ca.AuroraTopologyService.ClusterTopologyInfo>	topologyCache

Constructor Summary

Constructors

Constructor and Description
AuroraTopologyService() Initializes a service with topology default refresh rate.
AuroraTopologyService(int refreshRateInMilliseconds) Initializes a service with provided topology refresh rate.

Method Summary

Modifier and Type	Method and Description
void	addToDownHostList(@Nullable HostInfo downHost) Mark host as down.
void	clear() Clear topology cache for the current cluster.
void	clearAll() Clear topology cache for all clusters.
@Nullable List<HostInfo>	getCachedTopology() Get cached topology.
Set<String>	getDownHosts() Get a set of host names that were marked down.
@Nullable HostInfo	getLastUsedReaderHost() Get details about the most recent reader that the driver has successfully connected to.
List<HostInfo>	getTopology(Connection conn, boolean forceUpdate) Get cluster topology.
protected software.aws.rds.jdbc.postgresql.ca.AuroraTopologyService.ClusterTopologyInfo	queryForTopology(Connection conn) Obtain a cluster topology from database.
void	removeFromDownHostList(@Nullable HostInfo host) Unmark host as down.
void	setClusterId(String clusterId) Sets cluster Id for a host Different service hosts with the same cluster Id share topology cache.
void	setClusterInstanceTemplate(HostInfo clusterInstanceTemplate) Sets host details common to each host in the cluster, including the host dns pattern.
static void	setExpireTime(int expireTimeMs) Service hosts with the same cluster Id share cluster topology.
void	setLastUsedReaderHost(@Nullable HostInfo reader) Set details about the most recent reader that the driver has connected to.
void	setPerformanceMetrics(ClusterAwareMetrics metrics, boolean gatherMetrics) Initializes the performance metrics
void	setRefreshRate(int refreshRate) Set new topology refresh rate.

Methods inherited from class java.lang.Object

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

Field Detail

topologyCache

protected static final ExpiringCache<String,software.aws.rds.jdbc.postgresql.ca.AuroraTopologyService.ClusterTopologyInfo> topologyCache

clusterId

protected String clusterId

clusterInstanceTemplate

protected HostInfo clusterInstanceTemplate

metrics

protected @MonotonicNonNull ClusterAwareMetrics metrics

gatherPerfMetrics

protected boolean gatherPerfMetrics

Constructor Detail

AuroraTopologyService

public AuroraTopologyService()

Initializes a service with topology default refresh rate.

AuroraTopologyService

public AuroraTopologyService(int refreshRateInMilliseconds)

Initializes a service with provided topology refresh rate.

Parameters:

refreshRateInMilliseconds - Topology refresh rate in millis

Method Detail

setPerformanceMetrics

public void setPerformanceMetrics(ClusterAwareMetrics metrics,
                                  boolean gatherMetrics)

Initializes the performance metrics

Parameters:

metrics - The ClusterAwareMetrics instance that will be used to record metrics

gatherMetrics - The metric settings that decides whether or not the class should gather metrics

setExpireTime

public static void setExpireTime(int expireTimeMs)

Service hosts with the same cluster Id share cluster topology. Shared topology is cached for a specified period of time. This method sets cache expiration time in millis.

Parameters:

expireTimeMs - Topology cache expiration time in millis

setClusterId

public void setClusterId(String clusterId)

Sets cluster Id for a host Different service hosts with the same cluster Id share topology cache.

Specified by:

setClusterId in interface TopologyService

Parameters:

clusterId - Topology cluster Id

setClusterInstanceTemplate

public void setClusterInstanceTemplate(HostInfo clusterInstanceTemplate)

Sets host details common to each host in the cluster, including the host dns pattern. "?" (question mark) in a host dns pattern will be replaced with a host name to form a fully qualified dns host endpoint.

Examples: "?.mydomain.com", "db-host.?.mydomain.com"

Specified by:

setClusterInstanceTemplate in interface TopologyService

Parameters:

clusterInstanceTemplate - Cluster host details including host dns pattern.

getTopology

public List<HostInfo> getTopology(Connection conn,
                                  boolean forceUpdate)

Get cluster topology. It may require an extra call to database to fetch the latest topology. A cached copy of topology is returned if it's not yet outdated (controlled by refreshRateInMilliseconds).

Specified by:

getTopology in interface TopologyService

Parameters:

conn - A connection to database to fetch the latest topology, if needed.

forceUpdate - If true, it forces a service to ignore cached copy of topology and to fetch a fresh one.

Returns:

A list of hosts that describes cluster topology. A writer is always at position 0. Returns an empty list if topology isn't available or is invalid (doesn't contain a writer).

queryForTopology

protected software.aws.rds.jdbc.postgresql.ca.AuroraTopologyService.ClusterTopologyInfo queryForTopology(Connection conn)

Obtain a cluster topology from database.

Parameters:

conn - A connection to database to fetch the latest topology.

Returns:

A ClusterTopologyInfo instance which contains details of the fetched topology

getCachedTopology

public @Nullable List<HostInfo> getCachedTopology()

Get cached topology.

Specified by:

getCachedTopology in interface TopologyService

Returns:

List of hosts that represents topology. If there's no topology in the cache or the cached topology is outdated, it returns null.

getLastUsedReaderHost

public @Nullable HostInfo getLastUsedReaderHost()

Get details about the most recent reader that the driver has successfully connected to.

Specified by:

getLastUsedReaderHost in interface TopologyService

Returns:

The host details of the most recent reader connection. Returns null if the driver has not connected to a reader within the refresh rate period.

setLastUsedReaderHost

public void setLastUsedReaderHost(@Nullable HostInfo reader)

Set details about the most recent reader that the driver has connected to.

Specified by:

setLastUsedReaderHost in interface TopologyService

Parameters:

reader - A reader host.

getDownHosts

public Set<String> getDownHosts()

Get a set of host names that were marked down.

Specified by:

getDownHosts in interface TopologyService

Returns:

A set of host dns names with port (example: "host-1.my-domain.com:3306")

addToDownHostList

public void addToDownHostList(@Nullable HostInfo downHost)

Mark host as down. Host stays marked down until next topology refresh.

Specified by:

addToDownHostList in interface TopologyService

Parameters:

downHost - The HostInfo object representing the host to mark as down

removeFromDownHostList

public void removeFromDownHostList(@Nullable HostInfo host)

Unmark host as down. The host is removed from the list of down hosts

Specified by:

removeFromDownHostList in interface TopologyService

Parameters:

host - The HostInfo object representing the host to remove from the list of down hosts

setRefreshRate

public void setRefreshRate(int refreshRate)

Set new topology refresh rate. Different service hosts may have different topology refresh rate while sharing the same topology cache.

Specified by:

setRefreshRate in interface TopologyService

Parameters:

refreshRate - Topology refresh rate in millis.

clearAll

public void clearAll()

Clear topology cache for all clusters.

Specified by:

clearAll in interface TopologyService

clear

public void clear()

Clear topology cache for the current cluster.

Specified by:

clear in interface TopologyService