## com.mysql.jdbc
Class LoadBalancingConnectionProxy

    java.lang.Object
      com.mysql.jdbc.LoadBalancingConnectionProxy

All Implemented Interfaces:
  PingTarget, java.lang.reflect.InvocationHandler

    public class LoadBalancingConnectionProxy

extends java.lang.Object
implements java.lang.reflect.InvocationHandler, PingTarget

An implementation of java.sql.Connection 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
`protected class` `LoadBalancingConnectionProxy.ConnectionErrorFiringInvocationHandler`

Field Summary
`static java.lang.String` `BLACKLIST_TIMEOUT_PROPERTY_KEY`

Constructor Summary
`LoadBalancingConnectionProxy(java.util.List 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
`void` `addToGlobalBlacklist(java.lang.String host)`
`Connection` `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` `dealWithInvocationException(java.lang.reflect.InvocationTargetException e)`
`void` `doPing()`
`java.util.Map` `getGlobalBlacklist()`
`(package private) void` `invalidateCurrentConnection()` Closes current connection and removes it from required mappings.
`java.lang.Object` `invoke(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()`
`(package private) java.lang.Object` `proxyIfInterfaceIsJdbc(java.lang.Object toProxy, java.lang.Class clazz)` Recursively checks for interfaces on the given object to determine if it implements a java.sql interface, and if so, proxies the instance so that we can catch and fire SQL errors.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### 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 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` -
    `props` -
  Throws:
    `java.sql.SQLException`

Method Detail

### createConnectionForHost

    public Connection 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.

  Parameters:
    `hostPortSpec` -
  Returns:
  Throws:
    `java.sql.SQLException`

### dealWithInvocationException

    void dealWithInvocationException(java.lang.reflect.InvocationTargetException e)
                               throws java.sql.SQLException,
                                      java.lang.Throwable,
                                      java.lang.reflect.InvocationTargetException

  Parameters:
    `e` -
  Throws:
    `java.sql.SQLException`
    `java.lang.Throwable`
    `java.lang.reflect.InvocationTargetException`

### invalidateCurrentConnection

    void invalidateCurrentConnection()
                               throws java.sql.SQLException

  Closes current connection and removes it from required mappings.

  Throws:
    `java.sql.SQLException`

### invoke

    public java.lang.Object invoke(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).

  Specified by:
    `invoke` in interface `java.lang.reflect.InvocationHandler`
  Throws:
    `java.lang.Throwable`

### proxyIfInterfaceIsJdbc

    java.lang.Object proxyIfInterfaceIsJdbc(java.lang.Object toProxy,
                                            java.lang.Class clazz)

  Recursively checks for interfaces on the given object to determine if it implements a java.sql interface, and if so, proxies the instance so that we can catch and fire SQL errors.

  Parameters:
    `toProxy` -
    `clazz` -
  Returns:

### doPing

    public void doPing()
                throws java.sql.SQLException

  Specified by:
    `doPing` in interface `PingTarget`
  Throws:
    `java.sql.SQLException`

### addToGlobalBlacklist

    public void addToGlobalBlacklist(java.lang.String host)

### isGlobalBlacklistEnabled

    public boolean isGlobalBlacklistEnabled()

### getGlobalBlacklist

    public java.util.Map getGlobalBlacklist()