Package org.apache.flink.runtime.state.filesystem

Class AbstractFileStateBackend

  • All Implemented Interfaces:
    Serializable, CheckpointStorage, StateBackend
    @Deprecated
@PublicEvolving
public abstract class AbstractFileStateBackend
extends AbstractStateBackend
implements CheckpointStorage
    Deprecated.
    State backends should no longer implement CheckpointStorage functionality. Please inherit AbstractStateBackend instead. Custom checkpoint storage can be additionally implemented as a separate class.
    A base class for all state backends that store their metadata (and data) in files.

    This class takes the base checkpoint- and savepoint directory paths, but also accepts null for both of then, in which case creating externalized checkpoint is not possible, and it is not possible to create a savepoint with a default path. Null is accepted to enable implementations that only optionally support default savepoints and externalized checkpoints.

    Checkpoint Layout

    The state backend is configured with a base directory and persists the checkpoint data of specific checkpoints in specific subdirectories. For example, if the base directory was set to hdfs://namenode:port/flink-checkpoints/, the state backend will create a subdirectory with the job's ID that will contain the actual checkpoints: ( hdfs://namenode:port/flink-checkpoints/1b080b6e710aabbef8993ab18c6de98b)

    Each checkpoint individually will store all its files in a subdirectory that includes the checkpoint number, such as hdfs://namenode:port/flink-checkpoints/1b080b6e710aabbef8993ab18c6de98b/chk-17/.

    Savepoint Layout

    A savepoint that is set to be stored in path hdfs://namenode:port/flink-savepoints/, will create a subdirectory savepoint-jobId(0, 6)-randomDigits in which it stores all savepoint data. The random digits are added as "entropy" to avoid directory collisions.

    Metadata File

    A completed checkpoint writes its metadata into a file '"_metadata"'.

    See Also:
    Serialized Form

    • Constructor Detail

      • AbstractFileStateBackend

        protected AbstractFileStateBackend​(@Nullable
                                   URI baseCheckpointPath,
                                   @Nullable
                                   URI baseSavepointPath)
        Deprecated.
        Creates a backend with the given optional checkpoint- and savepoint base directories.
        Parameters:
        baseCheckpointPath - The base directory for checkpoints, or null, if none is configured.
        baseSavepointPath - The default directory for savepoints, or null, if none is set.

      • AbstractFileStateBackend

        protected AbstractFileStateBackend​(@Nullable
                                   Path baseCheckpointPath,
                                   @Nullable
                                   Path baseSavepointPath)
        Deprecated.
        Creates a backend with the given optional checkpoint- and savepoint base directories.
        Parameters:
        baseCheckpointPath - The base directory for checkpoints, or null, if none is configured.
        baseSavepointPath - The default directory for savepoints, or null, if none is set.

      • AbstractFileStateBackend

        protected AbstractFileStateBackend​(@Nullable
                                   Path baseCheckpointPath,
                                   @Nullable
                                   Path baseSavepointPath,
                                   ReadableConfig configuration)
        Deprecated.
        Creates a new backend using the given checkpoint-/savepoint directories, or the values defined in the given configuration. If a checkpoint-/savepoint parameter is not null, that value takes precedence over the value in the configuration. If the configuration does not specify a value, it is possible that the checkpoint-/savepoint directories in the backend will be null.

        This constructor can be used to create a backend that is based partially on a given backend and partially on a configuration.

        Parameters:
        baseCheckpointPath - The checkpoint base directory to use (or null).
        baseSavepointPath - The default savepoint directory to use (or null).
        configuration - The configuration to read values from.

    • Method Detail

      • getCheckpointPath

        @Nullable
public Path getCheckpointPath()
        Deprecated.
        Gets the checkpoint base directory. Jobs will create job-specific subdirectories for checkpoints within this directory. May be null, if not configured.
        Returns:
        The checkpoint base directory

      • getSavepointPath

        @Nullable
public Path getSavepointPath()
        Deprecated.
        Gets the directory where savepoints are stored by default (when no custom path is given to the savepoint trigger command).
        Returns:
        The default directory for savepoints, or null, if no default directory has been configured.

      • resolveCheckpoint

        public CompletedCheckpointStorageLocation resolveCheckpoint​(String pointer)
                                                     throws IOException
        Deprecated.
        Description copied from interface: CheckpointStorage
        Resolves the given pointer to a checkpoint/savepoint into a checkpoint location. The location supports reading the checkpoint metadata, or disposing the checkpoint storage location.
        Specified by:
        resolveCheckpoint in interface CheckpointStorage
        Parameters:
        pointer - The external checkpoint pointer to resolve.
        Returns:
        The checkpoint location handle.
        Throws:
        IOException - Thrown, if the state backend does not understand the pointer, or if the pointer could not be resolved due to an I/O error.