software.aws.rds.jdbc.postgresql.ca

Class ClusterAwareReaderFailoverHandler

java.lang.Object

software.aws.rds.jdbc.postgresql.ca.ClusterAwareReaderFailoverHandler

All Implemented Interfaces:

ReaderFailoverHandler

public class ClusterAwareReaderFailoverHandler
extends Object
implements ReaderFailoverHandler

An implementation of ReaderFailoverHandler.

The goal of the reader failover process is to connect to any available reader. In order to connect faster, this implementation tries to connect to two readers at the same time. The first successfully connected reader is returned as the process result. If both readers are unavailable (i.e. could not be connected to), the process picks up another pair of readers and repeats. If no reader connection has successfully been established, the process may consider connecting to a writer host, and other hosts marked as down.

Field Summary

Fields

Modifier and Type	Field and Description
protected Properties	connectionProps
protected ConnectionProvider	connProvider
protected static int	DEFAULT_FAILOVER_TIMEOUT
protected static int	DEFAULT_READER_CONNECT_TIMEOUT
protected int	maxFailoverTimeoutMs
protected int	timeoutMs
protected TopologyService	topologyService
protected static int	WRITER_CONNECTION_INDEX

Constructor Summary

Constructors

Constructor and Description
ClusterAwareReaderFailoverHandler(TopologyService topologyService, ConnectionProvider connProvider, Properties connectionProps)
ClusterAwareReaderFailoverHandler(TopologyService topologyService, ConnectionProvider connProvider, Properties connectionProps, int failoverTimeoutMs, int timeoutMs) ClusterAwareReaderFailoverHandler constructor.

Method Summary

Modifier and Type	Method and Description
ReaderFailoverResult	failover(List<HostInfo> hosts, @Nullable HostInfo currentHost) Called to start the reader failover process.
protected ReaderFailoverResult	failoverInternal(List<HostInfo> hosts, @Nullable HostInfo currentHost) Helper method for failover(List, HostInfo).
ReaderFailoverResult	getReaderConnection(List<HostInfo> hostList) Called to get any available reader connection.
protected void	setTimeoutMs(int timeoutMs) Set process timeout in millis.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_FAILOVER_TIMEOUT

protected static final int DEFAULT_FAILOVER_TIMEOUT

See Also:

Constant Field Values

DEFAULT_READER_CONNECT_TIMEOUT

protected static final int DEFAULT_READER_CONNECT_TIMEOUT

See Also:

Constant Field Values

WRITER_CONNECTION_INDEX

protected static final int WRITER_CONNECTION_INDEX

See Also:

Constant Field Values

maxFailoverTimeoutMs

protected int maxFailoverTimeoutMs

timeoutMs

protected int timeoutMs

connProvider

protected final ConnectionProvider connProvider

topologyService

protected final TopologyService topologyService

connectionProps

protected Properties connectionProps

Constructor Detail

ClusterAwareReaderFailoverHandler

public ClusterAwareReaderFailoverHandler(TopologyService topologyService,
                                         ConnectionProvider connProvider,
                                         Properties connectionProps)

ClusterAwareReaderFailoverHandler

public ClusterAwareReaderFailoverHandler(TopologyService topologyService,
                                         ConnectionProvider connProvider,
                                         Properties connectionProps,
                                         int failoverTimeoutMs,
                                         int timeoutMs)

ClusterAwareReaderFailoverHandler constructor.

Parameters:

topologyService - a topology service

connProvider - a connection provider

connectionProps - a set of properties for a new connections

failoverTimeoutMs - timeout for the entire reader failover process

timeoutMs - timeout for each individual connection attempt

Method Detail

setTimeoutMs

protected void setTimeoutMs(int timeoutMs)

Set process timeout in millis. Entire process of connecting to a reader will be limited by this time duration.

Parameters:

timeoutMs - Process timeout in millis

failover

public ReaderFailoverResult failover(List<HostInfo> hosts,
                                     @Nullable HostInfo currentHost)
                              throws SQLException

Called to start the reader failover process. This process tries to connect to any reader. If no reader is available then driver may also try to connect to a writer host, down hosts, and the current reader host.

Specified by:

failover in interface ReaderFailoverHandler

Parameters:

hosts - The latest cluster topology information that we had before connection failure.

currentHost - The currently connected host that has failed.

Returns:

ReaderFailoverResult The results of this process.

Throws:

SQLException - when a thread gets interrupted and failover fails

failoverInternal

protected ReaderFailoverResult failoverInternal(List<HostInfo> hosts,
                                                @Nullable HostInfo currentHost)
                                         throws SQLException

Helper method for failover(List, HostInfo).

Parameters:

hosts - List of hosts in the current topology

currentHost - The currently connected host

Returns:

The ReaderFailoverResult of the internal failover process

Throws:

SQLException - when a thread gets interrupted and failover fails

getReaderConnection

public ReaderFailoverResult getReaderConnection(List<HostInfo> hostList)
                                         throws SQLException

Called to get any available reader connection. If no reader is available then result of process is unsuccessful. This process will not attempt to connect to the writer host.

Specified by:

getReaderConnection in interface ReaderFailoverHandler

Parameters:

hostList - Current topology for the cluster.

Returns:

ReaderFailoverResult The results of this process.

Throws:

SQLException - when a thread gets interrupted and failover fails