Package com.mysql.cj.jdbc.ha

Interface BalanceStrategy

All Known Implementing Classes:
BestResponseTimeBalanceStrategy, RandomBalanceStrategy, SequentialBalanceStrategy, ServerAffinityStrategy
public interface BalanceStrategy
Implement this interface to provide a new load balancing strategy for URLs of the form "jdbc:mysql:loadbalance://..", and provide the implementation class name as the configuration parameter "loadBalanceStrategy". The driver will not pass in a Connection instance when calling init(), but it will pass in the Properties, otherwise it acts like a normal Extension. One instance of a strategy *per* JDBC connection instance will be created. If you need singleton-like behavior, you're on your own to provide it.

  • Method Summary

    Modifier and Type Method Description
    JdbcConnection pickConnection​(java.lang.reflect.InvocationHandler proxy, java.util.List<java.lang.String> configuredHosts, java.util.Map<java.lang.String,​JdbcConnection> liveConnections, long[] responseTimes, int numRetries)
    Called by the driver to pick a new connection to route requests over.

  • Method Details

    • pickConnection

      JdbcConnection pickConnection​(java.lang.reflect.InvocationHandler proxy, java.util.List<java.lang.String> configuredHosts, java.util.Map<java.lang.String,​JdbcConnection> liveConnections, long[] responseTimes, int numRetries) throws java.sql.SQLException
      Called by the driver to pick a new connection to route requests over. See LoadBalancedConnectionProxy.createConnectionForHost(String)
      Parameters:
      proxy - the InvocationHandler that deals with actual method calls to the JDBC connection, and serves as a factory for new connections for this strategy via the createConnectionForHost() method. This proxy takes care of maintaining the response time list, map of host/ports to live connections, and taking connections out of the live connections map if they receive a network-related error while they are in use by the application.
      configuredHosts - the list of hosts/ports (in "host:port" form) as passed in by the user.
      liveConnections - a map of host/ports to "live" connections to them.
      responseTimes - the list of response times for a transaction for each host in the configured hosts list.
      numRetries - the number of times the driver expects this strategy to re-try connection attempts if creating a new connection fails.
      Returns:
      the physical JDBC connection for the application to use, based upon the strategy employed.
      Throws:
      java.sql.SQLException - if a new connection can not be found or created by this strategy.