Package org.apache.camel.component.zookeepermaster.group.internal

Class ZooKeeperGroup<T extends NodeState>

java.lang.Object
org.apache.camel.component.zookeepermaster.group.internal.ZooKeeperGroup<T>
All Implemented Interfaces:
Closeable, AutoCloseable, Group<T>
Direct Known Subclasses:
ZooKeeperMultiGroup
public class ZooKeeperGroup<T extends NodeState> extends Object implements Group<T>

A utility that attempts to keep all data from all children of a ZK path locally cached. This class will watch the ZK path, respond to update/create/delete events, pull down the data, etc. You can register a listener that will get notified when changes occur.

IMPORTANT - it's not possible to stay transactionally in sync. Users of this class must be prepared for false-positives and false-negatives. Additionally, always use the version number when updating data to avoid overwriting another process' change.

  • Constructor Details

    • ZooKeeperGroup

      public ZooKeeperGroup(org.apache.curator.framework.CuratorFramework client, String path, Class<T> clazz)
      Parameters:
      client - the client
      path - path to watch

    • ZooKeeperGroup

      public ZooKeeperGroup(org.apache.curator.framework.CuratorFramework client, String path, Class<T> clazz, ThreadFactory threadFactory)
      Parameters:
      client - the client
      path - path to watch
      threadFactory - factory to use when creating internal threads

    • ZooKeeperGroup

      public ZooKeeperGroup(org.apache.curator.framework.CuratorFramework client, String path, Class<T> clazz, ExecutorService executorService)
      Parameters:
      client - the client
      path - path to watch
      executorService - ExecutorService to use for the ZooKeeperGroup's background thread

  • Method Details

    • start

      public void start()
      Start the cache. The cache is not started automatically. You must call this method.
      Specified by:
      start in interface Group<T extends NodeState>

    • close

      public void close() throws IOException
      Close/end the cache
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Specified by:
      close in interface Group<T extends NodeState>
      Throws:
      IOException - errors

    • isConnected

      public boolean isConnected()
      Description copied from interface: Group
      Are we connected with the cluster?
      Specified by:
      isConnected in interface Group<T extends NodeState>

    • add

      public void add(GroupListener<T> listener)
      Description copied from interface: Group
      Registers a listener which will be called when the cluster membership changes or the group is connected or disconnected.
      Specified by:
      add in interface Group<T extends NodeState>

    • remove

      public void remove(GroupListener<T> listener)
      Description copied from interface: Group
      Removes a previously added listener.
      Specified by:
      remove in interface Group<T extends NodeState>

    • update

      public void update(T state)
      Description copied from interface: Group
      Update the state of this group member. If the state is null, the member will leave the group. This method can be called even if the group is not started, in which case the state will be stored and updated when the group becomes started.
      Specified by:
      update in interface Group<T extends NodeState>
      Parameters:
      state - the new state of this group member

    • doUpdate

      protected void doUpdate(T state) throws Exception
      Throws:
      Exception

    • members

      public Map<String,T> members()
      Description copied from interface: Group
      Get the list of members connected to this group.
      Specified by:
      members in interface Group<T extends NodeState>

    • isMaster

      public boolean isMaster()
      Description copied from interface: Group
      Check if we are the master.
      Specified by:
      isMaster in interface Group<T extends NodeState>

    • master

      public T master()
      Description copied from interface: Group
      Retrieve the master node.
      Specified by:
      master in interface Group<T extends NodeState>

    • slaves

      public List<T> slaves()
      Description copied from interface: Group
      Retrieve the list of slaves.
      Specified by:
      slaves in interface Group<T extends NodeState>

    • getActiveChildren

      protected List<ChildData<T>> getActiveChildren()
      Filter stale nodes and return only active children from the current data.
      Returns:
      list of active children and data

    • getLastState

      public T getLastState()
      Description copied from interface: Group
      Gets the last state.

      This can be used by clients to access that last state, such as when the clients is being added as a listener but wants to retrieve the last state to be up to date when the client is added.

      Specified by:
      getLastState in interface Group<T extends NodeState>
      Returns:
      the state, or null if no last state yet.

    • getSequenceComparator

      public SequenceComparator getSequenceComparator()

    • getListenable

      public org.apache.curator.framework.listen.StandardListenerManager<GroupListener<T>> getListenable()
      Return the cache listenable
      Returns:
      listenable

    • getCurrentData

      public List<ChildData<T>> getCurrentData()
      Return the current data. There are no guarantees of accuracy. This is merely the most recent view of the data. The data is returned in sorted order.
      Returns:
      list of children and data

    • getCurrentData

      public ChildData<T> getCurrentData(String fullPath)
      Return the current data for the given path. There are no guarantees of accuracy. This is merely the most recent view of the data. If there is no child with that path, null is returned.
      Parameters:
      fullPath - full path to the node to check
      Returns:
      data or null

    • clearAndRefresh

      public void clearAndRefresh() throws Exception
      Clear out current data and begin a new query on the path
      Throws:
      Exception - errors

    • clearAndRefresh

      public void clearAndRefresh(boolean force, boolean sync) throws Exception
      Clear out current data and begin a new query on the path
      Parameters:
      force - - whether to force clear and refresh to trigger updates
      sync - - whether to run this synchronously (block current thread) or asynchronously
      Throws:
      Exception - errors

    • clear

      public void clear()
      Clears the current data without beginning a new query and without generating any events for listeners.

    • handleException

      protected void handleException(Throwable e)
      Default behavior is just to log the exception
      Parameters:
      e - the exception

    • remove

      protected void remove(String fullPath)

    • members

      public static <T> Map<String,T> members(com.fasterxml.jackson.databind.ObjectMapper mapper, org.apache.curator.framework.CuratorFramework curator, String path, Class<T> clazz) throws Exception
      Throws:
      Exception

    • getId

      public String getId()

    • isUnstable

      public boolean isUnstable()
      Returns an indication that the sequential, ephemeral node may be registered more than once for this group