Package 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 Details

  • Constructor Details

    • 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 Details

    • 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.

    • shouldExceptionTriggerConnectionSwitch

      protected 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:
      t - The Exception instance to check.
      Returns:
      true if the given exception should trigger a connection fail-over

    • isSourceConnection

      protected boolean isSourceConnection()
      Always returns 'true' as there are no "sources" and "replicas" in this type of connection.
      Specified by:
      isSourceConnection in class MultiHostConnectionProxy
      Returns:
      true if current connection is to a source host

    • invalidateConnection

      protected void invalidateConnection​(JdbcConnection conn) throws java.sql.SQLException
      Closes specified connection and removes it from required mappings.
      Overrides:
      invalidateConnection in class MultiHostConnectionProxy
      Parameters:
      conn - connection
      Throws:
      java.sql.SQLException - if an error occurs

    • pickNewConnection

      public 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 - 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.
      Overrides:
      createConnectionForHost in class MultiHostConnectionProxy
      Parameters:
      hostInfo - The host info instance.
      Returns:
      The new Connection instance.
      Throws:
      java.sql.SQLException - if an error occurs

    • syncSessionState

      protected void syncSessionState​(JdbcConnection source, JdbcConnection target, boolean readOnly) throws java.sql.SQLException
      Description copied from class: MultiHostConnectionProxy
      Synchronizes session state between two connections, allowing to override the read-only status.
      Overrides:
      syncSessionState in class MultiHostConnectionProxy
      Parameters:
      source - The connection where to get state from.
      target - The connection where to set state.
      readOnly - The new read-only status.
      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

    • doClose

      protected void doClose()
      Closes all live connections.
      Specified by:
      doClose in class MultiHostConnectionProxy

    • doAbortInternal

      protected void doAbortInternal()
      Aborts all live connections
      Specified by:
      doAbortInternal in class MultiHostConnectionProxy

    • doAbort

      protected void doAbort​(java.util.concurrent.Executor executor)
      Aborts all live connections, using the provided Executor.
      Specified by:
      doAbort in class MultiHostConnectionProxy
      Parameters:
      executor - executor

    • 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
      Parameters:
      proxy - proxy object
      method - method to invoke
      args - method parameters
      Returns:
      method result
      Throws:
      java.lang.Throwable - 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()