software.amazon.jdbc.plugin.staledns

Class AuroraStaleDnsPlugin

java.lang.Object

software.amazon.jdbc.plugin.AbstractConnectionPlugin

software.amazon.jdbc.plugin.staledns.AuroraStaleDnsPlugin

All Implemented Interfaces:

ConnectionPlugin

public class AuroraStaleDnsPlugin
extends AbstractConnectionPlugin

After Aurora DB cluster fail over is completed and a cluster has elected a new writer node, the corresponding cluster (writer) endpoint contains stale data and points to an old writer node. That old writer node plays a reader role after fail over and connecting with the cluster endpoint connects to it. In such case a user application expects a writer connection but practically gets connected to a reader. Any DML statements fail on the connection since the reader node allows just read-only statements.

Such stale DNS data usually lasts 20-40s, up to a minute. Update time is not predictable and depends on cluster control plane.

This plugin tries to recognize such a wrong connection to a reader when a writer connection is expected, and to mitigate it by reconnecting a proper new writer.

Constructor Summary

Constructors

Constructor and Description
AuroraStaleDnsPlugin(PluginService pluginService, java.util.Properties properties)

Method Summary

Modifier and Type	Method and Description
java.sql.Connection	connect(java.lang.String driverProtocol, HostSpec hostSpec, java.util.Properties props, boolean isInitialConnection, JdbcCallable<java.sql.Connection,java.sql.SQLException> connectFunc) Establishes a connection to the given host using the given driver protocol and properties.
<T,E extends java.lang.Exception> T	execute(java.lang.Class<T> resultClass, java.lang.Class<E> exceptionClass, java.lang.Object methodInvokeOn, java.lang.String methodName, JdbcCallable<T,E> jdbcMethodFunc, java.lang.Object[] jdbcMethodArgs)
java.util.Set<java.lang.String>	getSubscribedMethods()
void	initHostProvider(java.lang.String driverProtocol, java.lang.String initialUrl, java.util.Properties props, HostListProviderService hostListProviderService, JdbcCallable<java.lang.Void,java.sql.SQLException> initHostProviderFunc)
void	notifyNodeListChanged(java.util.Map<java.lang.String,java.util.EnumSet<NodeChangeOptions>> changes)

Methods inherited from class software.amazon.jdbc.plugin.AbstractConnectionPlugin

acceptsStrategy, forceConnect, getHostSpecByStrategy, getHostSpecByStrategy, notifyConnectionChanged

Methods inherited from class java.lang.Object

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

Constructor Detail

AuroraStaleDnsPlugin

public AuroraStaleDnsPlugin(PluginService pluginService,
                            java.util.Properties properties)

Method Detail

getSubscribedMethods

public java.util.Set<java.lang.String> getSubscribedMethods()

Specified by:

getSubscribedMethods in interface ConnectionPlugin

Specified by:

getSubscribedMethods in class AbstractConnectionPlugin

connect

public java.sql.Connection connect(java.lang.String driverProtocol,
                                   HostSpec hostSpec,
                                   java.util.Properties props,
                                   boolean isInitialConnection,
                                   JdbcCallable<java.sql.Connection,java.sql.SQLException> connectFunc)
                            throws java.sql.SQLException

Description copied from interface: ConnectionPlugin

Establishes a connection to the given host using the given driver protocol and properties. If a non-default ConnectionProvider has been set with Driver.setCustomConnectionProvider(ConnectionProvider) and ConnectionProvider.acceptsUrl(String, HostSpec, Properties) returns true for the given protocol, host, and properties, the connection will be created by the non-default ConnectionProvider. Otherwise, the connection will be created by the default ConnectionProvider. The default ConnectionProvider will be DriverConnectionProvider for connections requested via the DriverManager and DataSourceConnectionProvider for connections requested via an AwsWrapperDataSource.

Specified by:

connect in interface ConnectionPlugin

Overrides:

connect in class AbstractConnectionPlugin

Parameters:

driverProtocol - the driver protocol that should be used to establish the connection

hostSpec - the host details for the desired connection

props - the connection properties

isInitialConnection - a boolean indicating whether the current Connection is establishing an initial physical connection to the database or has already established a physical connection in the past

connectFunc - the function to call to continue the connect request down the connect pipeline

Returns:

a Connection to the requested host

Throws:

java.sql.SQLException - if there was an error establishing a Connection to the requested host

initHostProvider

public void initHostProvider(java.lang.String driverProtocol,
                             java.lang.String initialUrl,
                             java.util.Properties props,
                             HostListProviderService hostListProviderService,
                             JdbcCallable<java.lang.Void,java.sql.SQLException> initHostProviderFunc)
                      throws java.sql.SQLException

Specified by:

initHostProvider in interface ConnectionPlugin

Overrides:

initHostProvider in class AbstractConnectionPlugin

Throws:

java.sql.SQLException

execute

public <T,E extends java.lang.Exception> T execute(java.lang.Class<T> resultClass,
                                                   java.lang.Class<E> exceptionClass,
                                                   java.lang.Object methodInvokeOn,
                                                   java.lang.String methodName,
                                                   JdbcCallable<T,E> jdbcMethodFunc,
                                                   java.lang.Object[] jdbcMethodArgs)
                                            throws E extends java.lang.Exception

Specified by:

execute in interface ConnectionPlugin

Overrides:

execute in class AbstractConnectionPlugin

Throws:

E extends java.lang.Exception

notifyNodeListChanged

public void notifyNodeListChanged(java.util.Map<java.lang.String,java.util.EnumSet<NodeChangeOptions>> changes)

Specified by:

notifyNodeListChanged in interface ConnectionPlugin

Overrides:

notifyNodeListChanged in class AbstractConnectionPlugin