Package org.apache.hadoop.hbase.zookeeper

Class ZKWatcher

java.lang.Object
org.apache.hadoop.hbase.zookeeper.ZKWatcher
All Implemented Interfaces:
Closeable, AutoCloseable, Abortable, org.apache.zookeeper.Watcher
@Private public class ZKWatcher extends Object implements org.apache.zookeeper.Watcher, Abortable, Closeable
Acts as the single ZooKeeper Watcher. One instance of this is instantiated for each Master, RegionServer, and client process.

This is the only class that implements Watcher. Other internal classes which need to be notified of ZooKeeper events must register with the local instance of this watcher via registerListener(org.apache.hadoop.hbase.zookeeper.ZKListener).

This class also holds and manages the connection to ZooKeeper. Code to deal with connection related events and exceptions are handled here.

  • Field Details

  • Constructor Details

    • ZKWatcher

      public ZKWatcher(org.apache.hadoop.conf.Configuration conf, String identifier, Abortable abortable) throws ZooKeeperConnectionException, IOException
      Instantiate a ZooKeeper connection and watcher.
      Parameters:
      identifier - string that is passed to RecoverableZookeeper to be used as identifier for this instance. Use null for default.
      Throws:
      IOException - if the connection to ZooKeeper fails
      ZooKeeperConnectionException - if the client can't connect to ZooKeeper

    • ZKWatcher

      public ZKWatcher(org.apache.hadoop.conf.Configuration conf, String identifier, Abortable abortable, boolean canCreateBaseZNode) throws IOException, ZooKeeperConnectionException
      Instantiate a ZooKeeper connection and watcher.
      Parameters:
      conf - the configuration to use
      identifier - string that is passed to RecoverableZookeeper to be used as identifier for this instance. Use null for default.
      abortable - Can be null if there is on error there is no host to abort: e.g. client context.
      canCreateBaseZNode - true if a base ZNode can be created
      Throws:
      IOException - if the connection to ZooKeeper fails
      ZooKeeperConnectionException - if the client can't connect to ZooKeeper

    • ZKWatcher

      public ZKWatcher(org.apache.hadoop.conf.Configuration conf, String identifier, Abortable abortable, boolean canCreateBaseZNode, boolean clientZK) throws IOException, ZooKeeperConnectionException
      Instantiate a ZooKeeper connection and watcher.
      Parameters:
      conf - the configuration to use
      identifier - string that is passed to RecoverableZookeeper to be used as identifier for this instance. Use null for default.
      abortable - Can be null if there is on error there is no host to abort: e.g. client context.
      canCreateBaseZNode - true if a base ZNode can be created
      clientZK - whether this watcher is set to access client ZK
      Throws:
      IOException - if the connection to ZooKeeper fails
      ZooKeeperConnectionException - if the connection to Zookeeper fails when create base ZNodes

  • Method Details

    • createACL

      public List<org.apache.zookeeper.data.ACL> createACL(String node)

    • createACL

      public List<org.apache.zookeeper.data.ACL> createACL(String node, boolean isSecureZooKeeper)

    • createBaseZNodes

      private void createBaseZNodes() throws ZooKeeperConnectionException
      Throws:
      ZooKeeperConnectionException

    • checkAndSetZNodeAcls

      public void checkAndSetZNodeAcls()
      On master start, we check the znode ACLs under the root directory and set the ACLs properly if needed. If the cluster goes from an unsecure setup to a secure setup, this step is needed so that the existing znodes created with open permissions are now changed with restrictive perms.

    • setZnodeAclsRecursive

      private void setZnodeAclsRecursive(String znode) throws org.apache.zookeeper.KeeperException, InterruptedException
      Set the znode perms recursively. This will do post-order recursion, so that baseZnode ACLs will be set last in case the master fails in between.
      Parameters:
      znode - the ZNode to set the permissions for
      Throws:
      org.apache.zookeeper.KeeperException
      InterruptedException

    • isBaseZnodeAclSetup

      private boolean isBaseZnodeAclSetup(List<org.apache.zookeeper.data.ACL> acls) throws IOException
      Checks whether the ACLs returned from the base znode (/hbase) is set for secure setup.
      Parameters:
      acls - acls from zookeeper
      Returns:
      whether ACLs are set for the base znode
      Throws:
      IOException - if getting the current user fails

    • checkACLForSuperUsers

      private boolean checkACLForSuperUsers(String[] superUsers, List<org.apache.zookeeper.data.ACL> acls)

    • isSuperUserId

      public static boolean isSuperUserId(String[] superUsers, org.apache.zookeeper.data.Id id)

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • prefix

      public String prefix(String str)
      Adds this instance's identifier as a prefix to the passed str
      Parameters:
      str - String to amend.
      Returns:
      A new string with this instance's identifier as prefix: e.g. if passed 'hello world', the returned string could be

    • getMetaReplicaNodes

      public List<String> getMetaReplicaNodes() throws org.apache.zookeeper.KeeperException
      Get the znodes corresponding to the meta replicas from ZK
      Returns:
      list of znodes
      Throws:
      org.apache.zookeeper.KeeperException - if a ZooKeeper operation fails

    • getMetaReplicaNodesAndWatchChildren

      public List<String> getMetaReplicaNodesAndWatchChildren() throws org.apache.zookeeper.KeeperException
      Same as getMetaReplicaNodes() except that this also registers a watcher on base znode for subsequent CREATE/DELETE operations on child nodes.
      Throws:
      org.apache.zookeeper.KeeperException

    • filterMetaReplicaNodes

      private List<String> filterMetaReplicaNodes(List<String> nodes)
      Parameters:
      nodes - Input list of znodes
      Returns:
      Filtered list of znodes from nodes that belong to meta replica(s).

    • registerListener

      public void registerListener(ZKListener listener)
      Register the specified listener to receive ZooKeeper events.
      Parameters:
      listener - the listener to register

    • registerListenerFirst

      public void registerListenerFirst(ZKListener listener)
      Register the specified listener to receive ZooKeeper events and add it as the first in the list of current listeners.
      Parameters:
      listener - the listener to register

    • unregisterListener

      public void unregisterListener(ZKListener listener)

    • unregisterAllListeners

      public void unregisterAllListeners()
      Clean all existing listeners

    • getListeners

      public List<ZKListener> getListeners()
      Get a copy of current registered listeners

    • getNumberOfListeners

      public int getNumberOfListeners()
      Returns The number of currently registered listeners

    • getRecoverableZooKeeper

      public RecoverableZooKeeper getRecoverableZooKeeper()
      Get the connection to ZooKeeper.
      Returns:
      connection reference to zookeeper

    • reconnectAfterExpiration

      public void reconnectAfterExpiration() throws IOException, org.apache.zookeeper.KeeperException, InterruptedException
      Throws:
      IOException
      org.apache.zookeeper.KeeperException
      InterruptedException

    • getQuorum

      public String getQuorum()
      Get the quorum address of this instance.
      Returns:
      quorum string of this zookeeper connection instance

    • getZNodePaths

      public ZNodePaths getZNodePaths()
      Get the znodePaths.

      Mainly used for mocking as mockito can not mock a field access.

    • processEvent

      private void processEvent(org.apache.zookeeper.WatchedEvent event)

    • process

      public void process(org.apache.zookeeper.WatchedEvent event)
      Method called from ZooKeeper for events and connection status.

      Valid events are passed along to listeners. Connection status changes are dealt with locally.

      Specified by:
      process in interface org.apache.zookeeper.Watcher

    • connectionEvent

      private void connectionEvent(org.apache.zookeeper.WatchedEvent event)
      Called when there is a connection-related event via the Watcher callback.

      If Disconnected or Expired, this should shutdown the cluster. But, since we send a KeeperException.SessionExpiredException along with the abort call, it's possible for the Abortable to catch it and try to create a new session with ZooKeeper. This is what the client does in HCM.

      Parameters:
      event - the connection-related event

    • syncOrTimeout

      public void syncOrTimeout(String path) throws org.apache.zookeeper.KeeperException
      Forces a synchronization of this ZooKeeper client connection within a timeout. Enforcing a timeout lets the callers fail-fast rather than wait forever for the sync to finish.

      Executing this method before running other methods will ensure that the subsequent operations are up-to-date and consistent as of the time that the sync is complete.

      This is used for compareAndSwap type operations where we need to read the data of an existing node and delete or transition that node, utilizing the previously read version and data. We want to ensure that the version read is up-to-date from when we begin the operation.

      Throws:
      org.apache.zookeeper.KeeperException

    • keeperException

      public void keeperException(org.apache.zookeeper.KeeperException ke) throws org.apache.zookeeper.KeeperException
      Handles KeeperExceptions in client calls.

      This may be temporary but for now this gives one place to deal with these.

      TODO: Currently this method rethrows the exception to let the caller handle

      Parameters:
      ke - the exception to rethrow
      Throws:
      org.apache.zookeeper.KeeperException - if a ZooKeeper operation fails

    • interruptedException

      public void interruptedException(InterruptedException ie) throws org.apache.zookeeper.KeeperException
      Handles InterruptedExceptions in client calls.
      Parameters:
      ie - the InterruptedException instance thrown
      Throws:
      org.apache.zookeeper.KeeperException - the exception to throw, transformed from the InterruptedException

    • interruptedExceptionNoThrow

      public void interruptedExceptionNoThrow(InterruptedException ie, boolean throwLater)
      Log the InterruptedException and interrupt current thread
      Parameters:
      ie - The IterruptedException to log
      throwLater - Whether we will throw the exception latter

    • close

      public void close()
      Close the connection to ZooKeeper.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable

    • getConfiguration

      public org.apache.hadoop.conf.Configuration getConfiguration()

    • abort

      public void abort(String why, Throwable e)
      Description copied from interface: Abortable
      Abort the server or client.
      Specified by:
      abort in interface Abortable
      Parameters:
      why - Why we're aborting.
      e - Throwable that caused abort. Can be null.

    • isAborted

      public boolean isAborted()
      Description copied from interface: Abortable
      Check if the server or client was aborted.
      Specified by:
      isAborted in interface Abortable
      Returns:
      true if the server or client was aborted, false otherwise