com.mysql.jdbc

Class LoadBalancingConnectionProxy

java.lang.Object

com.mysql.jdbc.MultiHostConnectionProxy

com.mysql.jdbc.LoadBalancingConnectionProxy

All Implemented Interfaces:

PingTarget, java.lang.reflect.InvocationHandler

public class LoadBalancingConnectionProxy
extends MultiHostConnectionProxy
implements PingTarget

A proxy for a dynamic com.mysql.jdbc.Connection implementation that load balances requests across a series of MySQL JDBC connections, where the balancing takes place at transaction commit. Therefore, for this to work (at all), you must use transactions, even if only reading data. This implementation will invalidate connections that it detects have had communication errors when processing a request. Problematic hosts will be added to a global blacklist for loadBalanceBlacklistTimeout ms, after which they will be removed from the blacklist and made eligible once again to be selected for new connections. This implementation is thread-safe, but it's questionable whether sharing a connection instance amongst threads is a good idea, given that transactions are scoped to connections in JDBC.

Nested Class Summary

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

MultiHostConnectionProxy.JdbcInterfaceProxy

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	BLACKLIST_TIMEOUT_PROPERTY_KEY
protected java.util.Map<java.lang.String,ConnectionImpl>	liveConnections

Fields inherited from class com.mysql.jdbc.MultiHostConnectionProxy

autoReconnect, closedExplicitly, closedReason, currentConnection, hostList, isClosed, localProps, thisAsConnection

Constructor Summary

Constructors

Constructor and Description
LoadBalancingConnectionProxy(java.util.List<java.lang.String> hosts, java.util.Properties props) Creates a proxy for java.sql.Connection that routes requests between the given list of host:port and uses the given properties when creating connections.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	addHost(java.lang.String host) Adds a host to the hosts list.
void	addToGlobalBlacklist(java.lang.String host) Adds a host to the blacklist.
void	addToGlobalBlacklist(java.lang.String host, long timeout) Adds a host to the blacklist with the given timeout.
ConnectionImpl	createConnectionForHost(java.lang.String hostPortSpec) Creates a new physical connection for the given host:port and updates required internal mappings and statistics for that connection.
(package private) void	doAbort(java.util.concurrent.Executor executor) Aborts all live connections, using the provided Executor.
(package private) void	doAbortInternal() Aborts all live connections
(package private) void	doClose() Closes all live connections.
void	doPing() Pings live connections.
long	getActivePhysicalConnectionCount()
long	getConnectionGroupProxyID()
java.lang.String	getCurrentActiveHost()
long	getCurrentTransactionDuration()
java.util.Map<java.lang.String,java.lang.Long>	getGlobalBlacklist() Returns a local hosts blacklist, or a blacklist with a single host to be removed, while cleaning up expired records from the global blacklist.
(package private) MySQLConnection	getNewWrapperForThisAsConnection() Wraps this object with a new load balanced Connection instance.
long	getTotalPhysicalConnectionCount()
long	getTransactionCount()
boolean	inTransaction()
(package private) void	invalidateConnection(MySQLConnection conn) Closes specified connection and removes it from required mappings.
java.lang.Object	invokeMore(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args) Proxies method invocation on the java.sql.Connection interface, trapping "close", "isClosed" and "commit/rollback" to switch connections for load balancing.
boolean	isGlobalBlacklistEnabled() Checks if host blacklist management was enabled.
(package private) void	pickNewConnection() Picks the "best" connection to use for the next transaction based on the BalanceStrategy in use.
void	removeHost(java.lang.String host) Removes a host from the host list.
void	removeHostWhenNotInUse(java.lang.String host) Removes a host from the host list, allowing it some time to be released gracefully if needed.
(package private) boolean	shouldExceptionTriggerConnectionSwitch(java.lang.Throwable t) Consults the registered LoadBalanceExceptionChecker if the given exception should trigger a connection fail-over.
(package private) boolean	shouldExceptionTriggerFailover(java.lang.Throwable t) Deprecated.

Methods inherited from class com.mysql.jdbc.MultiHostConnectionProxy

dealWithInvocationException, getNewJdbcInterfaceProxy, initializeHostsSpecs, invalidateCurrentConnection, invoke, proxyIfIsJdbcInterface, syncSessionState, syncSessionState

Methods inherited from class java.lang.Object

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

Field Detail

liveConnections

protected java.util.Map<java.lang.String,ConnectionImpl> liveConnections

BLACKLIST_TIMEOUT_PROPERTY_KEY

public static final java.lang.String BLACKLIST_TIMEOUT_PROPERTY_KEY

See Also:

Constant Field Values

Constructor Detail

LoadBalancingConnectionProxy

LoadBalancingConnectionProxy(java.util.List<java.lang.String> hosts,
                            java.util.Properties props)
                       throws java.sql.SQLException

Creates a proxy for java.sql.Connection that routes requests between the given list of host:port and uses the given properties when creating connections.

Parameters:

hosts - The list of the hosts to load balance.

props - Connection properties from where to get initial settings and to be used in new connections.

Throws:

java.sql.SQLException

Method Detail

getNewWrapperForThisAsConnection

MySQLConnection getNewWrapperForThisAsConnection()
                                           throws java.sql.SQLException

Wraps this object with a new load balanced Connection instance.

Overrides:

getNewWrapperForThisAsConnection in class MultiHostConnectionProxy

Returns:

The connection object instance that wraps 'this'.

Throws:

java.sql.SQLException

shouldExceptionTriggerFailover

@Deprecated
boolean shouldExceptionTriggerFailover(java.lang.Throwable t)

Deprecated.

shouldExceptionTriggerConnectionSwitch

boolean shouldExceptionTriggerConnectionSwitch(java.lang.Throwable t)

Consults the registered LoadBalanceExceptionChecker if the given exception should trigger a connection fail-over.

Specified by:

shouldExceptionTriggerConnectionSwitch in class MultiHostConnectionProxy

Parameters:

ex - The Exception instance to check.

Returns:

invalidateConnection

void invalidateConnection(MySQLConnection conn)
                    throws java.sql.SQLException

Closes specified connection and removes it from required mappings.

Overrides:

invalidateConnection in class MultiHostConnectionProxy

Parameters:

conn -

Throws:

java.sql.SQLException

pickNewConnection

void pickNewConnection()
                 throws java.sql.SQLException

Picks the "best" connection to use for the next transaction based on the BalanceStrategy in use.

Specified by:

pickNewConnection in class MultiHostConnectionProxy

Throws:

java.sql.SQLException

createConnectionForHost

public ConnectionImpl createConnectionForHost(java.lang.String hostPortSpec)
                                       throws java.sql.SQLException

Creates a new physical connection for the given host:port and updates required internal mappings and statistics for that connection.

Overrides:

createConnectionForHost in class MultiHostConnectionProxy

Parameters:

hostPortSpec - The host:port specification.

Returns:

The new Connection instance.

Throws:

java.sql.SQLException

doClose

void doClose()

Closes all live connections.

Specified by:

doClose in class MultiHostConnectionProxy

doAbortInternal

void doAbortInternal()

Aborts all live connections

Specified by:

doAbortInternal in class MultiHostConnectionProxy

doAbort

void doAbort(java.util.concurrent.Executor executor)

Aborts all live connections, using the provided Executor.

Specified by:

doAbort in class MultiHostConnectionProxy

invokeMore

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

Proxies method invocation on the java.sql.Connection interface, trapping "close", "isClosed" and "commit/rollback" to switch connections for load balancing. This is the continuation of MultiHostConnectionProxy#invoke(Object, Method, Object[]).

Specified by:

invokeMore in class MultiHostConnectionProxy

Throws:

java.lang.Throwable

doPing

public void doPing()
            throws java.sql.SQLException

Pings live connections.

Specified by:

doPing in interface PingTarget

Throws:

java.sql.SQLException

addToGlobalBlacklist

public void addToGlobalBlacklist(java.lang.String host,
                        long timeout)

Adds a host to the blacklist with the given timeout.

Parameters:

host - The host to be blacklisted.

timeout - The blacklist timeout for this entry.

addToGlobalBlacklist

public void addToGlobalBlacklist(java.lang.String host)

Adds a host to the blacklist.

Parameters:

host - The host to be blacklisted.

isGlobalBlacklistEnabled

public boolean isGlobalBlacklistEnabled()

Checks if host blacklist management was enabled.

Returns:

getGlobalBlacklist

public java.util.Map<java.lang.String,java.lang.Long> getGlobalBlacklist()

Returns a local hosts blacklist, or a blacklist with a single host to be removed, while cleaning up expired records from the global blacklist.

Returns:

A local hosts blacklist.

removeHostWhenNotInUse

public void removeHostWhenNotInUse(java.lang.String host)
                            throws java.sql.SQLException

Removes a host from the host list, allowing it some time to be released gracefully if needed.

Parameters:

host - The host to be removed.

Throws:

java.sql.SQLException

removeHost

public void removeHost(java.lang.String host)
                throws java.sql.SQLException

Removes a host from the host list.

Parameters:

host - The host to be removed.

Throws:

java.sql.SQLException

addHost

public boolean addHost(java.lang.String host)

Adds a host to the hosts list.

Parameters:

host - The host to be added.

Returns:

inTransaction

public boolean inTransaction()

getTransactionCount

public long getTransactionCount()

getActivePhysicalConnectionCount

public long getActivePhysicalConnectionCount()

getTotalPhysicalConnectionCount

public long getTotalPhysicalConnectionCount()

getConnectionGroupProxyID

public long getConnectionGroupProxyID()

getCurrentActiveHost

public java.lang.String getCurrentActiveHost()

getCurrentTransactionDuration

public long getCurrentTransactionDuration()