com.mysql.cj.jdbc.ha

Class LoadBalancedConnectionProxy

java.lang.Object

com.mysql.cj.jdbc.ha.MultiHostConnectionProxy

com.mysql.cj.jdbc.ha.LoadBalancedConnectionProxy

All Implemented Interfaces:

PingTarget, java.lang.reflect.InvocationHandler

public class LoadBalancedConnectionProxy
extends MultiHostConnectionProxy
implements PingTarget

A proxy for a dynamic com.mysql.cj.jdbc.JdbcConnection 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 blocklist for loadBalanceBlocklistTimeout ms, after which they will be removed from the blocklist 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.

Field Summary

Fields

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

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

connectionUrl, lastExceptionDealtWith

Constructor Summary

Constructors

Constructor and Description
LoadBalancedConnectionProxy(ConnectionUrl connectionUrl) Creates a proxy for java.sql.Connection that routes requests between the hosts in the connection URL.

Method Summary

Modifier and Type	Method and Description
boolean	addHost(java.lang.String hostPortPair) Adds a host to the hosts list.
void	addToGlobalBlacklist(java.lang.String host) Deprecated.
void	addToGlobalBlacklist(java.lang.String host, long timeout) Deprecated.
void	addToGlobalBlocklist(java.lang.String host) Adds a host to the blocklist.
void	addToGlobalBlocklist(java.lang.String host, long timeout) Adds a host to the blocklist with the given timeout.
ConnectionImpl	createConnectionForHost(HostInfo hostInfo) Creates a new physical connection for the given HostInfo and updates required internal mappings and statistics for that connection.
ConnectionImpl	createConnectionForHost(java.lang.String hostPortPair) Creates a new physical connection for the given host:port info.
static LoadBalancedConnection	createProxyInstance(ConnectionUrl connectionUrl) Static factory to create LoadBalancedConnection instances.
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() Deprecated.
java.util.Map<java.lang.String,java.lang.Long>	getGlobalBlocklist() Returns a local hosts blocklist, while cleaning up expired records from the global blocklist, or a blocklist with the hosts to be removed.
long	getTotalPhysicalConnectionCount()
long	getTransactionCount()
boolean	inTransaction()
boolean	isGlobalBlacklistEnabled() Deprecated.
boolean	isGlobalBlocklistEnabled() Checks if host blocklist management was enabled.
void	pickNewConnection() Picks the "best" connection to use for the next transaction based on the BalanceStrategy in use.
protected void	propagateProxyDown(JdbcConnection proxyConn) Propagates the connection proxy down through all live connections.
void	removeFromGlobalBlacklist(java.lang.String host) Deprecated.
void	removeFromGlobalBlocklist(java.lang.String host) Removes a host from the blocklist.
void	removeHost(java.lang.String hostPortPair) Removes a host from the host list.
void	removeHostWhenNotInUse(java.lang.String hostPortPair) Removes a host from the host list, allowing it some time to be released gracefully if needed.
boolean	shouldExceptionTriggerFailover(java.lang.Throwable t) Deprecated.

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

allowedOnClosedConnection, getParentProxy, getProxy, invoke, setProxy

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

Constructor Detail

LoadBalancedConnectionProxy

public LoadBalancedConnectionProxy(ConnectionUrl connectionUrl)
                            throws java.sql.SQLException

Creates a proxy for java.sql.Connection that routes requests between the hosts in the connection URL.

Parameters:

connectionUrl - The connection URL containing the hosts to load balance.

Throws:

java.sql.SQLException - if an error occurs

Method Detail

createProxyInstance

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

Static factory to create LoadBalancedConnection instances.

Parameters:

connectionUrl - The connection URL containing the hosts in a load-balance setup.

Returns:

A LoadBalancedConnection proxy.

Throws:

java.sql.SQLException - if an error occurs

propagateProxyDown

protected void propagateProxyDown(JdbcConnection proxyConn)

Propagates the connection proxy down through all live connections.

Overrides:

propagateProxyDown in class MultiHostConnectionProxy

Parameters:

proxyConn - The top level connection in the multi-host connections chain.

shouldExceptionTriggerFailover

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

Deprecated.

pickNewConnection

public void pickNewConnection()
                       throws java.sql.SQLException

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

Throws:

java.sql.SQLException - if an error occurs

createConnectionForHost

public ConnectionImpl createConnectionForHost(HostInfo hostInfo)
                                       throws java.sql.SQLException

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

Parameters:

hostInfo - The host info instance.

Returns:

The new Connection instance.

Throws:

java.sql.SQLException - if an error occurs

createConnectionForHost

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

Creates a new physical connection for the given host:port info. If the this connection's connection URL knows about this host:port then its host info is used, otherwise a new host info based on current connection URL defaults is spawned.

Parameters:

hostPortPair - The host:port pair identifying the host to connect to.

Returns:

The new Connection instance.

Throws:

java.sql.SQLException - if an error occurs

doPing

public void doPing()
            throws java.sql.SQLException

Pings live connections.

Specified by:

doPing in interface PingTarget

Throws:

java.sql.SQLException - if an error occurs

addToGlobalBlocklist

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

Adds a host to the blocklist with the given timeout.

Parameters:

host - The host to be blocklisted.

timeout - The blocklist timeout for this entry.

removeFromGlobalBlocklist

public void removeFromGlobalBlocklist(java.lang.String host)

Removes a host from the blocklist.

Parameters:

host - The host to be removed from the blocklist.

removeFromGlobalBlacklist

@Deprecated
public void removeFromGlobalBlacklist(java.lang.String host)

Deprecated.

Use removeFromGlobalBlocklist(String) instead.

Parameters:

host - host

addToGlobalBlacklist

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

Deprecated.

Use addToGlobalBlocklist(String, long) instead.

Parameters:

host - The host to be blocklisted.

timeout - The blocklist timeout for this entry.

addToGlobalBlocklist

public void addToGlobalBlocklist(java.lang.String host)

Adds a host to the blocklist.

Parameters:

host - The host to be blocklisted.

addToGlobalBlacklist

@Deprecated
public void addToGlobalBlacklist(java.lang.String host)

Deprecated.

Use addToGlobalBlocklist(String) instead.

Parameters:

host - The host to be blocklisted.

isGlobalBlocklistEnabled

public boolean isGlobalBlocklistEnabled()

Checks if host blocklist management was enabled.

Returns:

true if host blocklist management was enabled

isGlobalBlacklistEnabled

@Deprecated
public boolean isGlobalBlacklistEnabled()

Deprecated.

Use isGlobalBlocklistEnabled() instead.

Returns:

true if host blocklist management was enabled

getGlobalBlocklist

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

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

Returns:

A local hosts blocklist.

getGlobalBlacklist

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

Deprecated.

Use getGlobalBlocklist() instead.

Returns:

A local hosts blocklist.

removeHostWhenNotInUse

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

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

Parameters:

hostPortPair - The host to be removed.

Throws:

java.sql.SQLException - if an error occurs

removeHost

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

Removes a host from the host list.

Parameters:

hostPortPair - The host to be removed.

Throws:

java.sql.SQLException - if an error occurs

addHost

public boolean addHost(java.lang.String hostPortPair)

Adds a host to the hosts list.

Parameters:

hostPortPair - The host to be added.

Returns:

true if host was added and false if the host list already contains it

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()