Package org.apache.flink.runtime.state

Class CheckpointStorageLocationReference

java.lang.Object
org.apache.flink.runtime.state.CheckpointStorageLocationReference
All Implemented Interfaces:
Serializable
public class CheckpointStorageLocationReference extends Object implements Serializable
A reference to a storage location. This is a wrapper around an array of bytes that are subject to interpretation by the state backend's storage locations (similar as a serializer needs to interpret byte streams). There is special handling for a 'default location', which can be used as an optimization by state backends, when no extra information is needed to determine where the checkpoints should be stored (all information can be derived from the configuration and the checkpoint id).

Why is this simply a byte array?

The reference is represented via raw bytes, which are subject to interpretation by the state backends. We did not add any more typing and serialization abstraction in between, because these types need to serialize/deserialize fast in between network streams (byte buffers) and barriers. We may ultimately add some more typing if we simply keep the byte buffers for the checkpoint barriers and forward them, thus saving decoding and re-encoding these references repeatedly.

See Also:

  • Constructor Details

    • CheckpointStorageLocationReference

      public CheckpointStorageLocationReference(byte[] encodedReference)
      Creates a new location reference.
      Parameters:
      encodedReference - The location reference, represented as bytes (non null)

  • Method Details

    • getReferenceBytes

      public byte[] getReferenceBytes()
      Gets the reference bytes.

      Important: For efficiency, this method does not make a defensive copy, so the caller must not modify the bytes in the array.

    • isDefaultReference

      public boolean isDefaultReference()
      Returns true, if this object is the default reference.

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • readResolve

      protected final Object readResolve() throws ObjectStreamException
      readResolve() preserves the singleton property of the default value.
      Throws:
      ObjectStreamException

    • getDefault

      public static CheckpointStorageLocationReference getDefault()