Package org.apache.hadoop.hdfs.server.federation.store.driver

Class StateStoreDriver

java.lang.Object
org.apache.hadoop.hdfs.server.federation.store.driver.StateStoreDriver
All Implemented Interfaces:
StateStoreRecordOperations
Direct Known Subclasses:
StateStoreBaseImpl
@Public @Evolving public abstract class StateStoreDriver extends Object implements StateStoreRecordOperations
Driver class for an implementation of a StateStoreService provider. Driver implementations will extend this class and implement some of the default methods.

  • Constructor Details

    • StateStoreDriver

      public StateStoreDriver()

  • Method Details

    • init

      public boolean init(org.apache.hadoop.conf.Configuration config, String id, Collection<Class<? extends BaseRecord>> records, StateStoreMetrics stateStoreMetrics)
      Initialize the state store connection.
      Parameters:
      config - Configuration for the driver.
      id - Identifier for the driver.
      records - Records that are supported.
      stateStoreMetrics - State store metrics.
      Returns:
      If initialized and ready, false if failed to initialize driver.

    • getConf

      protected org.apache.hadoop.conf.Configuration getConf()
      Get the State Store configuration.
      Returns:
      Configuration for the State Store.

    • getIdentifier

      public String getIdentifier()
      Gets a unique identifier for the running task/process. Typically, the router address.
      Returns:
      Unique identifier for the running task.

    • getMetrics

      public StateStoreMetrics getMetrics()
      Get the metrics for the State Store.
      Returns:
      State Store metrics.

    • initDriver

      public abstract boolean initDriver()
      Prepare the driver to access data storage.
      Returns:
      True if the driver was successfully initialized. If false is returned, the state store will periodically attempt to re-initialize the driver and the router will remain in safe mode until the driver is initialized.

    • initRecordStorage

      public abstract <T extends BaseRecord> boolean initRecordStorage(String className, Class<T> clazz)
      Initialize storage for a single record class.
      Type Parameters:
      T - Type of the state store record.
      Parameters:
      className - String reference of the record class to initialize, used to construct paths and file names for the record. Determined by configuration settings for the specific driver.
      clazz - Record type corresponding to the provided name.
      Returns:
      True if successful, false otherwise.

    • isDriverReady

      public abstract boolean isDriverReady()
      Check if the driver is currently running and the data store connection is valid.
      Returns:
      True if the driver is initialized and the data store is ready.

    • verifyDriverReady

      public void verifyDriverReady() throws StateStoreUnavailableException
      Check if the driver is ready to be used and throw an exception otherwise.
      Throws:
      StateStoreUnavailableException - If the driver is not ready.

    • close

      public void close() throws Exception
      Close the State Store driver connection.
      Throws:
      Exception - if something goes wrong while closing the state store driver connection.

    • getTime

      public long getTime()
      Returns the current time synchronization from the underlying store. Override for stores that supply a current date. The data store driver is responsible for maintaining the official synchronization time/date for all distributed components.
      Returns:
      Current time stamp, used for all synchronization dates.

    • handleOverwriteAndDelete

      public <R extends BaseRecord> List<R> handleOverwriteAndDelete(List<R> commitRecords, List<R> deleteRecords) throws IOException
      Try to overwrite records in commitRecords and remove records in deleteRecords. Should return null if async mode is used. Else return removed records.
      Type Parameters:
      R - record class
      Parameters:
      commitRecords - records to overwrite in state store
      deleteRecords - records to remove from state store
      Returns:
      null if async mode is used, else removed records
      Throws:
      IOException - when there is a failure during overwriting or deletion