com.mysql.cj.jdbc.ha

Class FailoverConnectionProxy

java.lang.Object

com.mysql.cj.jdbc.ha.MultiHostConnectionProxy

com.mysql.cj.jdbc.ha.FailoverConnectionProxy

All Implemented Interfaces:

java.lang.reflect.InvocationHandler

public class FailoverConnectionProxy
extends MultiHostConnectionProxy

A proxy for a dynamic com.mysql.cj.jdbc.JdbcConnection implementation that provides failover features for list of hosts. Connection switching occurs on communications related exceptions and/or user defined settings, namely when one of the conditions set in 'secondsBeforeRetrySource' or 'queriesBeforeRetrySource' is met.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
(package private) class	FailoverConnectionProxy.FailoverJdbcInterfaceProxy Proxy class to intercept and deal with errors that may occur in any object bound to the current connection.

Nested classes/interfaces inherited from class com.mysql.cj.jdbc.ha.MultiHostConnectionProxy

MultiHostConnectionProxy.JdbcInterfaceProxy

Field Summary

Fields

Modifier and Type	Field and Description
private int	currentHostIndex
private static int	DEFAULT_PRIMARY_HOST_INDEX
private boolean	enableFallBackToPrimaryHost
private boolean	explicitlyAutoCommit
private java.lang.Boolean	explicitlyReadOnly
private boolean	failoverReadOnly
private static java.lang.String	METHOD_COMMIT
private static java.lang.String	METHOD_ROLLBACK
private static java.lang.String	METHOD_SET_AUTO_COMMIT
private static java.lang.String	METHOD_SET_READ_ONLY
private static int	NO_CONNECTION_INDEX
private long	primaryHostFailTimeMillis
private int	primaryHostIndex
private long	queriesBeforeRetryPrimaryHost
private long	queriesIssuedSinceFailover
private int	retriesAllDown
private int	secondsBeforeRetryPrimaryHost

Fields inherited from class com.mysql.cj.jdbc.ha.MultiHostConnectionProxy

autoReconnect, closedExplicitly, closedReason, connectionUrl, currentConnection, hostsList, isClosed, lastExceptionDealtWith, parentProxyConnection, thisAsConnection, topProxyConnection

Constructor Summary

Constructors

Modifier	Constructor and Description
private	FailoverConnectionProxy(ConnectionUrl connectionUrl) Instantiates a new FailoverConnectionProxy for the given list of hosts and connection properties.

Method Summary

Modifier and Type	Method and Description
(package private) boolean	connectedToPrimaryHost() Checks if this proxy is using the primary host in the underlying connection.
(package private) boolean	connectedToSecondaryHost() Checks if this proxy is using a secondary host in the underlying connection.
private void	connectTo(int hostIndex) Connects this dynamic failover connection proxy to the host pointed out by the given host index.
(package private) ConnectionImpl	createConnectionForHostIndex(int hostIndex) Creates a new connection instance for host pointed out by the given host index.
static JdbcConnection	createProxyInstance(ConnectionUrl connectionUrl)
(package private) void	doAbort(java.util.concurrent.Executor executor) Aborts current connection using the given executor.
(package private) void	doAbortInternal() Aborts current connection.
(package private) void	doClose() Closes current connection.
private void	failOver() Initiates a default failover procedure starting at the current connection host index.
private void	failOver(int failedHostIdx) Initiates a default failover procedure starting at the given host index.
(package private) void	fallBackToPrimaryIfAvailable() Falls back to primary host or keep current connection if primary not available.
(package private) MultiHostConnectionProxy.JdbcInterfaceProxy	getNewJdbcInterfaceProxy(java.lang.Object toProxy) Gets locally bound instances of FailoverJdbcInterfaceProxy.
(package private) void	incrementQueriesIssuedSinceFailover() Increments counter for query executions.
java.lang.Object	invokeMore(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args) Continuation of the method invocation process, to be implemented within each subclass.
(package private) boolean	isConnected() Checks if there is a underlying connection for this proxy.
(package private) boolean	isPrimaryHostIndex(int hostIndex) Checks if the given host index points to the primary host.
(package private) boolean	isSourceConnection() Checks if current connection is to a source host.
private int	nextHost(int currHostIdx, boolean vouchForPrimaryHost) Gets the next host on the hosts list.
(package private) void	pickNewConnection() Picks the "best" connection to use from now on.
private boolean	queriesBeforeRetryPrimaryHostIsMet() Checks the condition set by the property 'queriesBeforeRetrySource'.
(package private) boolean	readyToFallBackToPrimaryHost() Checks if at least one of the required conditions to fall back to primary host is met, which is determined by the properties 'queriesBeforeRetrySource' and 'secondsBeforeRetrySource'.
private void	resetAutoFallBackCounters() Resets auto-fall back counters.
private boolean	secondsBeforeRetryPrimaryHostIsMet() Checks the condition set by the property 'secondsBeforeRetrySource'.
(package private) boolean	shouldExceptionTriggerConnectionSwitch(java.lang.Throwable t) Checks if the given throwable should trigger a connection switch.
private void	switchCurrentConnectionTo(int hostIndex, JdbcConnection connection) Replaces the previous underlying connection by the connection given.

Methods inherited from class com.mysql.cj.jdbc.ha.MultiHostConnectionProxy

allowedOnClosedConnection, createConnectionForHost, dealWithInvocationException, getNewWrapperForThisAsConnection, getParentProxy, getProxy, initializeHostsSpecs, invalidateConnection, invalidateCurrentConnection, invoke, isMasterConnection, propagateProxyDown, proxyIfReturnTypeIsJdbcInterface, setProxy, syncSessionState, syncSessionState

Methods inherited from class java.lang.Object

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

Field Detail

METHOD_SET_READ_ONLY

private static final java.lang.String METHOD_SET_READ_ONLY

See Also:

Constant Field Values

METHOD_SET_AUTO_COMMIT

private static final java.lang.String METHOD_SET_AUTO_COMMIT

See Also:

Constant Field Values

METHOD_COMMIT

private static final java.lang.String METHOD_COMMIT

See Also:

Constant Field Values

METHOD_ROLLBACK

private static final java.lang.String METHOD_ROLLBACK

See Also:

Constant Field Values

NO_CONNECTION_INDEX

private static final int NO_CONNECTION_INDEX

See Also:

Constant Field Values

DEFAULT_PRIMARY_HOST_INDEX

private static final int DEFAULT_PRIMARY_HOST_INDEX

See Also:

Constant Field Values

secondsBeforeRetryPrimaryHost

private int secondsBeforeRetryPrimaryHost

queriesBeforeRetryPrimaryHost

private long queriesBeforeRetryPrimaryHost

failoverReadOnly

private boolean failoverReadOnly

retriesAllDown

private int retriesAllDown

currentHostIndex

private int currentHostIndex

primaryHostIndex

private int primaryHostIndex

explicitlyReadOnly

private java.lang.Boolean explicitlyReadOnly

explicitlyAutoCommit

private boolean explicitlyAutoCommit

enableFallBackToPrimaryHost

private boolean enableFallBackToPrimaryHost

primaryHostFailTimeMillis

private long primaryHostFailTimeMillis

queriesIssuedSinceFailover

private long queriesIssuedSinceFailover

Constructor Detail

FailoverConnectionProxy

private FailoverConnectionProxy(ConnectionUrl connectionUrl)
                         throws java.sql.SQLException

Instantiates a new FailoverConnectionProxy for the given list of hosts and connection properties.

Parameters:

connectionUrl - ConnectionUrl instance containing the lists of hosts available to switch on.

Throws:

java.sql.SQLException - if an error occurs

Method Detail

createProxyInstance

public static JdbcConnection createProxyInstance(ConnectionUrl connectionUrl)
                                          throws java.sql.SQLException

Throws:

java.sql.SQLException

getNewJdbcInterfaceProxy

MultiHostConnectionProxy.JdbcInterfaceProxy getNewJdbcInterfaceProxy(java.lang.Object toProxy)

Gets locally bound instances of FailoverJdbcInterfaceProxy.

Overrides:

getNewJdbcInterfaceProxy in class MultiHostConnectionProxy

Parameters:

toProxy - The object instance to be proxied.

Returns:

The new InvocationHandler instance.

shouldExceptionTriggerConnectionSwitch

boolean shouldExceptionTriggerConnectionSwitch(java.lang.Throwable t)

Description copied from class: MultiHostConnectionProxy

Checks if the given throwable should trigger a connection switch.

Specified by:

shouldExceptionTriggerConnectionSwitch in class MultiHostConnectionProxy

Parameters:

t - The Throwable instance to analyze.

Returns:

true if the given throwable should trigger a connection switch

isSourceConnection

boolean isSourceConnection()

Checks if current connection is to a source host.

Specified by:

isSourceConnection in class MultiHostConnectionProxy

Returns:

true if current connection is to a source host

pickNewConnection

void pickNewConnection()
                throws java.sql.SQLException

Description copied from class: MultiHostConnectionProxy

Picks the "best" connection to use from now on. Each subclass needs to implement its connection switch strategy on it.

Specified by:

pickNewConnection in class MultiHostConnectionProxy

Throws:

java.sql.SQLException - if an error occurs

createConnectionForHostIndex

ConnectionImpl createConnectionForHostIndex(int hostIndex)
                                     throws java.sql.SQLException

Creates a new connection instance for host pointed out by the given host index.

Parameters:

hostIndex - The host index in the global hosts list.

Returns:

The new connection instance.

Throws:

java.sql.SQLException - if an error occurs

connectTo

private void connectTo(int hostIndex)
                throws java.sql.SQLException

Connects this dynamic failover connection proxy to the host pointed out by the given host index.

Parameters:

hostIndex - The host index in the global hosts list.

Throws:

java.sql.SQLException - if an error occurs

switchCurrentConnectionTo

private void switchCurrentConnectionTo(int hostIndex,
                                       JdbcConnection connection)
                                throws java.sql.SQLException

Replaces the previous underlying connection by the connection given. State from previous connection, if any, is synchronized with the new one.

Parameters:

hostIndex - The host index in the global hosts list that matches the given connection.

connection - The connection instance to switch to.

Throws:

java.sql.SQLException - if an error occurs

failOver

private void failOver()
               throws java.sql.SQLException

Initiates a default failover procedure starting at the current connection host index.

Throws:

java.sql.SQLException - if an error occurs

failOver

private void failOver(int failedHostIdx)
               throws java.sql.SQLException

Initiates a default failover procedure starting at the given host index. This process tries to connect, sequentially, to the next host in the list. The primary host may or may not be excluded from the connection attempts.

Parameters:

failedHostIdx - The host index where to start from. First connection attempt will be the next one.

Throws:

java.sql.SQLException - if an error occurs

fallBackToPrimaryIfAvailable

void fallBackToPrimaryIfAvailable()

Falls back to primary host or keep current connection if primary not available.

nextHost

private int nextHost(int currHostIdx,
                     boolean vouchForPrimaryHost)

Gets the next host on the hosts list. Uses a round-robin algorithm to find the next element, but it may skip the index for the primary host. General rules to include the primary host are: - not currently connected to any host. - primary host is vouched (usually because connection to all secondary hosts has failed). - conditions to fall back to primary host are met (or they are disabled).

Parameters:

currHostIdx - Current host index.

vouchForPrimaryHost - Allows to return the primary host index even if the usual required conditions aren't met.

Returns:

next host index

incrementQueriesIssuedSinceFailover

void incrementQueriesIssuedSinceFailover()

Increments counter for query executions.

readyToFallBackToPrimaryHost

boolean readyToFallBackToPrimaryHost()

Checks if at least one of the required conditions to fall back to primary host is met, which is determined by the properties 'queriesBeforeRetrySource' and 'secondsBeforeRetrySource'.

Returns:

true if ready

isConnected

boolean isConnected()

Checks if there is a underlying connection for this proxy.

Returns:

true if there is a connection

isPrimaryHostIndex

boolean isPrimaryHostIndex(int hostIndex)

Checks if the given host index points to the primary host.

Parameters:

hostIndex - The host index in the global hosts list.

Returns:

true if so

connectedToPrimaryHost

boolean connectedToPrimaryHost()

Checks if this proxy is using the primary host in the underlying connection.

Returns:

true if so

connectedToSecondaryHost

boolean connectedToSecondaryHost()

Checks if this proxy is using a secondary host in the underlying connection.

Returns:

true if so

secondsBeforeRetryPrimaryHostIsMet

private boolean secondsBeforeRetryPrimaryHostIsMet()

Checks the condition set by the property 'secondsBeforeRetrySource'.

Returns:

value

queriesBeforeRetryPrimaryHostIsMet

private boolean queriesBeforeRetryPrimaryHostIsMet()

Checks the condition set by the property 'queriesBeforeRetrySource'.

Returns:

value

resetAutoFallBackCounters

private void resetAutoFallBackCounters()

Resets auto-fall back counters.

doClose

void doClose()
      throws java.sql.SQLException

Closes current connection.

Specified by:

doClose in class MultiHostConnectionProxy

Throws:

java.sql.SQLException - if an error occurs

doAbortInternal

void doAbortInternal()
              throws java.sql.SQLException

Aborts current connection.

Specified by:

doAbortInternal in class MultiHostConnectionProxy

Throws:

java.sql.SQLException - if an error occurs

doAbort

void doAbort(java.util.concurrent.Executor executor)
      throws java.sql.SQLException

Aborts current connection using the given executor.

Specified by:

doAbort in class MultiHostConnectionProxy

Parameters:

executor - executor

Throws:

java.sql.SQLException - if an error occurs

invokeMore

public java.lang.Object invokeMore(java.lang.Object proxy,
                                   java.lang.reflect.Method method,
                                   java.lang.Object[] args)
                            throws java.lang.Throwable

Description copied from class: MultiHostConnectionProxy

Continuation of the method invocation process, to be implemented within each subclass.

Specified by:

invokeMore in class MultiHostConnectionProxy

Parameters:

proxy - proxy object

method - method to invoke

args - method parameters

Returns:

method result

Throws:

java.lang.Throwable - if an error occurs