com.mysql.jdbc
Class LoadBalancingConnectionProxy

java.lang.Object
  extended by 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()