software.amazon.jdbc.hostlistprovider

Class TopologyUtils

java.lang.Object

software.amazon.jdbc.hostlistprovider.TopologyUtils

Direct Known Subclasses:

AuroraTopologyUtils, MultiAzTopologyUtils

public abstract class TopologyUtils
extends java.lang.Object

An abstract class defining utility methods that can be used to retrieve and process a variety of database topology information. This class can be overridden to define logic specific to various database engine deployments (e.g. Aurora, Multi-AZ, Global Aurora etc.).

Field Summary

Fields

Modifier and Type	Field and Description
protected static int	DEFAULT_QUERY_TIMEOUT_MS
protected TopologyDialect	dialect
protected HostSpecBuilder	hostSpecBuilder
protected java.util.concurrent.Executor	networkTimeoutExecutor

Constructor Summary

Constructors

Constructor and Description
TopologyUtils(TopologyDialect dialect, HostSpecBuilder hostSpecBuilder)

Method Summary

Modifier and Type	Method and Description
HostSpec	createHost(java.lang.String instanceId, java.lang.String instanceName, boolean isWriter, long weight, java.lang.Float cpuPercent, java.lang.Float lag, java.sql.Timestamp lastUpdateTime, HostSpec initialHostSpec, HostSpec instanceTemplate) Creates a HostSpec from the given topology information, including a load value.
HostSpec	createHost(java.lang.String instanceId, java.lang.String instanceName, boolean isWriter, long weight, java.sql.Timestamp lastUpdateTime, HostSpec initialHostSpec, HostSpec instanceTemplate) Creates a HostSpec from the given topology information.
protected abstract @Nullable java.util.List<HostSpec>	getHosts(java.sql.Connection conn, java.sql.ResultSet rs, HostSpec initialHostSpec, HostSpec instanceTemplate)
abstract boolean	isWriterInstance(java.sql.Connection connection) Evaluate whether the given connection is to a writer instance.
@Nullable java.util.List<HostSpec>	queryForTopology(java.sql.Connection conn, HostSpec initialHostSpec, HostSpec instanceTemplate) Query the database for information for each instance in the database topology.
protected Pair<java.lang.Integer,java.lang.Boolean>	setNetworkTimeout(java.sql.Connection conn)
protected @Nullable java.util.List<HostSpec>	verifyWriter(@Nullable java.util.List<HostSpec> allHosts)

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_QUERY_TIMEOUT_MS

protected static final int DEFAULT_QUERY_TIMEOUT_MS

See Also:

Constant Field Values

networkTimeoutExecutor

protected final java.util.concurrent.Executor networkTimeoutExecutor

dialect

protected final TopologyDialect dialect

hostSpecBuilder

protected final HostSpecBuilder hostSpecBuilder

Constructor Detail

TopologyUtils

public TopologyUtils(TopologyDialect dialect,
                     HostSpecBuilder hostSpecBuilder)

Method Detail

queryForTopology

public @Nullable java.util.List<HostSpec> queryForTopology(java.sql.Connection conn,
                                                           HostSpec initialHostSpec,
                                                           HostSpec instanceTemplate)
                                                    throws java.sql.SQLException

Query the database for information for each instance in the database topology.

Parameters:

conn - the connection to use to query the database.

initialHostSpec - the HostSpec that was used to initially connect.

instanceTemplate - the template HostSpec to use when constructing new HostSpec objects from the data returned by the topology query.

Returns:

a list of HostSpec objects representing the results of the topology query.

Throws:

java.sql.SQLException - if an error occurs when executing the topology or processing the results.

setNetworkTimeout

protected Pair<java.lang.Integer,java.lang.Boolean> setNetworkTimeout(java.sql.Connection conn)

getHosts

protected abstract @Nullable java.util.List<HostSpec> getHosts(java.sql.Connection conn,
                                                               java.sql.ResultSet rs,
                                                               HostSpec initialHostSpec,
                                                               HostSpec instanceTemplate)
                                                        throws java.sql.SQLException

Throws:

java.sql.SQLException

verifyWriter

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

createHost

public HostSpec createHost(java.lang.String instanceId,
                           java.lang.String instanceName,
                           boolean isWriter,
                           long weight,
                           java.sql.Timestamp lastUpdateTime,
                           HostSpec initialHostSpec,
                           HostSpec instanceTemplate)

Creates a HostSpec from the given topology information.

Parameters:

instanceId - the database instance identifier, e.g. "mydb-instance-1" or "db-WQFQKBTL2LQUPIEFIFBGENS4ZQ".

instanceName - the database instance name, e.g. "mydb-instance-1.cluster-xxxxx.region.rds.amazonaws.com".

isWriter - true if this is a writer instance, false for reader.

weight - the instance weight for load balancing.

lastUpdateTime - the timestamp of the last update to this instance's information.

initialHostSpec - the original host specification used for connecting.

instanceTemplate - the template used to construct the new HostSpec.

Returns:

a HostSpec representing the given information.

createHost

public HostSpec createHost(java.lang.String instanceId,
                           java.lang.String instanceName,
                           boolean isWriter,
                           long weight,
                           java.lang.Float cpuPercent,
                           java.lang.Float lag,
                           java.sql.Timestamp lastUpdateTime,
                           HostSpec initialHostSpec,
                           HostSpec instanceTemplate)

Creates a HostSpec from the given topology information, including a load value.

Parameters:

instanceId - the database instance identifier.

instanceName - the database instance name.

isWriter - true if this is a writer instance, false for reader.

weight - the instance weight for load balancing.

lastUpdateTime - the timestamp of the last update to this instance's information.

initialHostSpec - the original host specification used for connecting.

instanceTemplate - the template used to construct the new HostSpec.

Returns:

a HostSpec representing the given information.

isWriterInstance

public abstract boolean isWriterInstance(java.sql.Connection connection)
                                  throws java.sql.SQLException

Evaluate whether the given connection is to a writer instance.

Parameters:

connection - the connection to evaluate.

Returns:

true if the connection is to a writer instance, false otherwise.

Throws:

java.sql.SQLException - if an exception occurs when querying the database or processing the database response.