Package org.apache.beam.sdk.state

Interface BagState<T>

Type Parameters:
T - The type of elements in the bag.
All Superinterfaces:
GroupingState<T,Iterable<T>>, ReadableState<Iterable<T>>, State
public interface BagState<T> extends GroupingState<T,Iterable<T>>
A ReadableState cell containing a bag of values. Items can be added to the bag and the contents read out.

Implementations of this form of state are expected to implement GroupingState.add(InputT) efficiently, not via a sequence of read-modify-write.

  • Method Summary

    Modifier and Type
    Method
    Description
    Iterable<T>
    read()
    Read the current value, blocking until it is available.
    BagState<T>
    readLater()
    Indicate that the value will be read later.

    Methods inherited from interface org.apache.beam.sdk.state.GroupingState

    add, isEmpty

    Methods inherited from interface org.apache.beam.sdk.state.State

    clear

  • Method Details

    • read

      @Nonnull Iterable<T> read()
      Description copied from interface: ReadableState
      Read the current value, blocking until it is available.

      If there will be many calls to ReadableState.read() for different state in short succession, you should first call ReadableState.readLater() for all of them so the reads can potentially be batched (depending on the underlying implementation}.

      The returned object should be independent of the underlying state. Any direct modification of the returned object should not modify state without going through the appropriate state interface, and modification to the state should not be mirrored in the returned object.

      Specified by:
      read in interface ReadableState<T>

    • readLater

      BagState<T> readLater()
      Description copied from interface: ReadableState
      Indicate that the value will be read later.

      This allows an implementation to start an asynchronous prefetch or to include this state in the next batch of reads.

      Specified by:
      readLater in interface GroupingState<T,Iterable<T>>
      Specified by:
      readLater in interface ReadableState<T>
      Returns:
      this for convenient chaining