Package org.apache.solr.cloud.overseer

Class ZkStateWriter

java.lang.Object
org.apache.solr.cloud.overseer.ZkStateWriter
public class ZkStateWriter extends Object
ZkStateWriter is responsible for writing updates to the cluster state stored in ZooKeeper for collections each of which gets their own individual state.json in ZK.

Updates to the cluster state are specified using the enqueueUpdate(ClusterState, List, ZkWriteCallback) method. The class buffers updates to reduce the number of writes to ZK. The buffered updates are flushed during enqueueUpdate automatically if necessary. The writePendingUpdates() can be used to force flush any pending updates.

If either enqueueUpdate(ClusterState, List, ZkWriteCallback) or writePendingUpdates() throws a KeeperException.BadVersionException then the internal buffered state of the class is suspect and the current instance of the class should be discarded and a new instance should be created and used for any future updates.

  • Field Details

    • NO_OP

      public static ZkWriteCommand NO_OP
      Represents a no-op ZkWriteCommand which will result in no modification to cluster state

    • reader

      protected final org.apache.solr.common.cloud.ZkStateReader reader

    • stats

      protected final Stats stats

    • updates

      protected Map<String,ZkWriteCommand> updates

    • clusterState

      protected org.apache.solr.common.cloud.ClusterState clusterState

    • lastUpdatedTime

      protected long lastUpdatedTime

    • invalidState

      protected boolean invalidState
      Set to true if we ever get a BadVersionException so that we can disallow future operations with this instance

    • minStateByteLenForCompression

      protected int minStateByteLenForCompression

    • compressor

      protected org.apache.solr.common.util.Compressor compressor

  • Constructor Details

    • ZkStateWriter

      public ZkStateWriter(org.apache.solr.common.cloud.ZkStateReader zkStateReader, Stats stats, int minStateByteLenForCompression, org.apache.solr.common.util.Compressor compressor)

  • Method Details

    • updateClusterState

      public void updateClusterState(Function<org.apache.solr.common.cloud.ClusterState,org.apache.solr.common.cloud.ClusterState> fun)
      if any collection is updated not through this class (directly written to ZK, then it needs to be updated locally)

    • enqueueUpdate

      public org.apache.solr.common.cloud.ClusterState enqueueUpdate(org.apache.solr.common.cloud.ClusterState prevState, List<ZkWriteCommand> cmds, ZkStateWriter.ZkWriteCallback callback) throws IllegalStateException, Exception
      Applies the given ZkWriteCommand on the prevState. The modified ClusterState is returned and it is expected that the caller will use the returned cluster state for the subsequent invocation of this method.

      The modified state may be buffered or flushed to ZooKeeper depending on the internal buffering logic of this class. The hasPendingUpdates() method may be used to determine if the last enqueue operation resulted in buffered state. The method writePendingUpdates() can be used to force an immediate flush of pending cluster state changes.

      Parameters:
      prevState - the cluster state information on which the given cmd is applied
      cmds - the list of ZkWriteCommand which specifies the change to be applied to cluster state in atomic
      callback - a ZkStateWriter.ZkWriteCallback object to be used for any callbacks
      Returns:
      modified cluster state created after applying cmd to prevState . If cmd is a no-op (NO_OP) then the prevState is returned unmodified.
      Throws:
      IllegalStateException - if the current instance is no longer usable. The current instance must be discarded.
      Exception - on an error in ZK operations or callback. If a flush to ZooKeeper results in a KeeperException.BadVersionException this instance becomes unusable and must be discarded

    • hasPendingUpdates

      public boolean hasPendingUpdates()

    • writeUpdate

      public org.apache.solr.common.cloud.ClusterState writeUpdate(ZkWriteCommand command) throws IllegalStateException, org.apache.zookeeper.KeeperException, InterruptedException
      Throws:
      IllegalStateException
      org.apache.zookeeper.KeeperException
      InterruptedException

    • writePendingUpdates

      public org.apache.solr.common.cloud.ClusterState writePendingUpdates() throws org.apache.zookeeper.KeeperException, InterruptedException
      Throws:
      org.apache.zookeeper.KeeperException
      InterruptedException

    • writePendingUpdates

      public org.apache.solr.common.cloud.ClusterState writePendingUpdates(Map<String,ZkWriteCommand> updates, boolean resetPendingUpdateCounters) throws IllegalStateException, org.apache.zookeeper.KeeperException, InterruptedException
      Writes all pending updates to ZooKeeper and returns the modified cluster state
      Returns:
      the modified cluster state
      Throws:
      IllegalStateException - if the current instance is no longer usable and must be discarded
      org.apache.zookeeper.KeeperException - if any ZooKeeper operation results in an error
      InterruptedException - if the current thread is interrupted

    • resetPendingUpdateCounters

      public void resetPendingUpdateCounters()

    • getClusterState

      public org.apache.solr.common.cloud.ClusterState getClusterState()
      Returns:
      the most up-to-date cluster state until the last enqueueUpdate operation