Package org.apache.flink.runtime.state

Class RetrievableStreamStateHandle<T extends Serializable>

java.lang.Object
org.apache.flink.runtime.state.RetrievableStreamStateHandle<T>
Type Parameters:
T - type of the retrievable object which is stored under the wrapped stream handle
All Implemented Interfaces:
Closeable, Serializable, AutoCloseable, RetrievableStateHandle<T>, StateObject, StreamStateHandle
public class RetrievableStreamStateHandle<T extends Serializable> extends Object implements StreamStateHandle, RetrievableStateHandle<T>, Closeable
Wrapper around a StreamStateHandle to make the referenced state object retrievable trough a simple get call. This implementation expects that the object was serialized through default serialization of Java's ObjectOutputStream.
See Also:

  • Constructor Details

    • RetrievableStreamStateHandle

      public RetrievableStreamStateHandle(StreamStateHandle streamStateHandle)

    • RetrievableStreamStateHandle

      public RetrievableStreamStateHandle(org.apache.flink.core.fs.Path filePath, long stateSize)

  • Method Details

    • retrieveState

      public T retrieveState() throws IOException, ClassNotFoundException
      Description copied from interface: RetrievableStateHandle
      Retrieves the object that was previously written to state.
      Specified by:
      retrieveState in interface RetrievableStateHandle<T extends Serializable>
      Throws:
      IOException
      ClassNotFoundException

    • openInputStream

      public org.apache.flink.core.fs.FSDataInputStream openInputStream() throws IOException
      Description copied from interface: StreamStateHandle
      Returns an FSDataInputStream that can be used to read back the data that was previously written to the stream.
      Specified by:
      openInputStream in interface StreamStateHandle
      Throws:
      IOException

    • asBytesIfInMemory

      public Optional<byte[]> asBytesIfInMemory()
      Specified by:
      asBytesIfInMemory in interface StreamStateHandle
      Returns:
      Content of this handle as bytes array if it is already in memory.

    • maybeGetPath

      public Optional<org.apache.flink.core.fs.Path> maybeGetPath()
      Specified by:
      maybeGetPath in interface StreamStateHandle
      Returns:
      Path to an underlying file represented by this StreamStateHandle or Optional.empty() if there is no such file.

    • getStreamStateHandleID

      public PhysicalStateHandleID getStreamStateHandleID()
      Specified by:
      getStreamStateHandleID in interface StreamStateHandle
      Returns:
      a unique identifier of this handle.

    • discardState

      public void discardState() throws Exception
      Description copied from interface: StateObject
      Discards the state referred to and solemnly owned by this handle, to free up resources in the persistent storage. This method is called when the state represented by this object will not be used anymore.
      Specified by:
      discardState in interface StateObject
      Throws:
      Exception

    • getStateSize

      public long getStateSize()
      Description copied from interface: StateObject
      Returns the size of the state in bytes. If the size is not known, this method should return 0.

      The values produced by this method are only used for informational purposes and for metrics/monitoring. If this method returns wrong values, the checkpoints and recovery will still behave correctly. However, efficiency may be impacted (wrong space pre-allocation) and functionality that depends on metrics (like monitoring) will be impacted.

      Note for implementors: This method should not perform any I/O operations while obtaining the state size (hence it does not declare throwing an IOException). Instead, the state size should be stored in the state object, or should be computable from the state stored in this object. The reason is that this method is called frequently by several parts of the checkpointing and issuing I/O requests from this method accumulates a heavy I/O load on the storage system at higher scale.

      Specified by:
      getStateSize in interface StateObject
      Returns:
      Size of the state in bytes.

    • collectSizeStats

      public void collectSizeStats(StateObject.StateObjectSizeStatsCollector collector)
      Description copied from interface: StateObject
      Collects statistics about state size and location from the state object.
      Specified by:
      collectSizeStats in interface StateObject
      Parameters:
      collector - the statistics collector.

    • close

      public void close() throws IOException
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Throws:
      IOException