Package com.mysql.cj.jdbc.ha.ca

Class AuroraTopologyService

java.lang.Object
com.mysql.cj.jdbc.ha.ca.AuroraTopologyService
All Implemented Interfaces:
CanCollectPerformanceMetrics, TopologyService
public class AuroraTopologyService
extends java.lang.Object
implements TopologyService, CanCollectPerformanceMetrics
An implementation of topology service for Aurora RDS. It uses information_schema.replica_host_status table to obtain cluster topology and caches it. Different instances of this service with the same 'clusterId' shares the same topology cache. Cache also includes a list of down hosts. That helps to avoid unnecessary attempts to connect them.

  • Field Details

  • Constructor Details

    • AuroraTopologyService

      public AuroraTopologyService​(Log log)
      Initializes a service with topology default refresh rate.

    • AuroraTopologyService

      public AuroraTopologyService​(int refreshRateInMilliseconds, Log log)
      Initializes a service with provided topology refresh rate.
      Parameters:
      refreshRateInMilliseconds - Topology refresh rate in millis

  • Method Details

    • setExpireTime

      public static void setExpireTime​(int expireTimeMs)
      Service instances with the same cluster Id share cluster topology. Shared topology is cached for a specified period of time. This method sets cache expiration time in millis.
      Parameters:
      expireTimeMs - Topology cache expiration time in millis

    • setClusterId

      public void setClusterId​(java.lang.String clusterId)
      Sets cluster Id for a service instance. Different service instances with the same cluster Id share topology cache.
      Specified by:
      setClusterId in interface TopologyService
      Parameters:
      clusterId - Topology cluster Id

    • setClusterInstanceTemplate

      public void setClusterInstanceTemplate​(HostInfo clusterInstanceTemplate)
      Sets host details common to each instance in the cluster, including the host dns pattern. "?" (question mark) in a host dns pattern will be replaced with a host instance name to form a fully qualified dns host endpoint.

      Examples: "?.mydomain.com", "db-instance.?.mydomain.com"

      Specified by:
      setClusterInstanceTemplate in interface TopologyService
      Parameters:
      clusterInstanceTemplate - Cluster instance details including host dns pattern.

    • getTopology

      public java.util.List<HostInfo> getTopology​(JdbcConnection conn, boolean forceUpdate)
      Get cluster topology. It may require an extra call to database to fetch the latest topology. A cached copy of topology is returned if it's not yet outdated (controlled by refreshRateInMilliseconds).
      Specified by:
      getTopology in interface TopologyService
      Parameters:
      conn - A connection to database to fetch the latest topology, if needed.
      forceUpdate - If true, it forces a service to ignore cached copy of topology and to fetch a fresh one.
      Returns:
      A list of hosts that describes cluster topology. A writer is always at position 0. Returns an empty list if topology isn't available or is invalid (doesn't contain a writer).

    • queryForTopology

      protected com.mysql.cj.jdbc.ha.ca.AuroraTopologyService.ClusterTopologyInfo queryForTopology​(JdbcConnection conn)
      Query the database for the cluster topology and use the results to record information about the topology.
      Parameters:
      conn - A connection to database to fetch the latest topology.
      Returns:
      Cluster topology details.

    • getCachedTopology

      public java.util.List<HostInfo> getCachedTopology()
      Get cached topology.
      Specified by:
      getCachedTopology in interface TopologyService
      Returns:
      List of hosts that represents topology. If there's no topology in the cache or the cached topology is outdated, it returns null.

    • getLastUsedReaderHost

      public HostInfo getLastUsedReaderHost()
      Get details about the most recent reader that the driver has successfully connected to.
      Specified by:
      getLastUsedReaderHost in interface TopologyService
      Returns:
      The host details of the most recent reader connection. Returns null if the driver has not connected to a reader within the refresh rate period.

    • setLastUsedReaderHost

      public void setLastUsedReaderHost​(HostInfo reader)
      Set details about the most recent reader that the driver has connected to.
      Specified by:
      setLastUsedReaderHost in interface TopologyService
      Parameters:
      reader - A reader host.

    • getHostByName

      public HostInfo getHostByName​(JdbcConnection conn)
      Return the HostInfo object that is associated with a provided connection from the topology host list.
      Specified by:
      getHostByName in interface TopologyService
      Parameters:
      conn - A connection to database.
      Returns:
      The HostInfo object from the topology host list. Returns null if the connection host is not found in the latest topology.

    • getDownHosts

      public java.util.Set<java.lang.String> getDownHosts()
      Get a set of instance names that were marked down.
      Specified by:
      getDownHosts in interface TopologyService
      Returns:
      A set of instance dns names with port (example: "instance-1.my-domain.com:3306")

    • addToDownHostList

      public void addToDownHostList​(HostInfo downHost)
      Mark host as down. Host stays marked down until next topology refresh.
      Specified by:
      addToDownHostList in interface TopologyService
      Parameters:
      downHost - The HostInfo object representing the host to mark as down

    • removeFromDownHostList

      public void removeFromDownHostList​(HostInfo host)
      Unmark host as down. The host is removed from the list of down hosts
      Specified by:
      removeFromDownHostList in interface TopologyService
      Parameters:
      host - The HostInfo object representing the host to remove from the list of down hosts

    • isMultiWriterCluster

      public boolean isMultiWriterCluster()
      Check if cached topology belongs to multi-writer cluster.
      Specified by:
      isMultiWriterCluster in interface TopologyService
      Returns:
      True, if it's multi-writer cluster.

    • setRefreshRate

      public void setRefreshRate​(int refreshRate)
      Set new topology refresh rate. Different service instances may have different topology refresh rate while sharing the same topology cache.
      Specified by:
      setRefreshRate in interface TopologyService
      Parameters:
      refreshRate - Topology refresh rate in millis.

    • clearAll

      public void clearAll()
      Clear topology cache for all clusters.
      Specified by:
      clearAll in interface TopologyService

    • clear

      public void clear()
      Clear topology cache for the current cluster.
      Specified by:
      clear in interface TopologyService

    • setPerformanceMetricsEnabled

      public void setPerformanceMetricsEnabled​(boolean isEnabled)
      This service implementation supports metrics. This method enables collecting internal metrics. Metrics are disabled by default.
      Specified by:
      setPerformanceMetricsEnabled in interface CanCollectPerformanceMetrics
      Parameters:
      isEnabled - True to enable internal metrics.

    • reportMetrics

      public void reportMetrics​(Log log)
      Report collected metrics to a provided logger.
      Specified by:
      reportMetrics in interface CanCollectPerformanceMetrics
      Parameters:
      log - Logger to report collected metrics to.