Package org.apache.beam.sdk.fn.stream

Class DataStreams.DataStreamDecoder<T>

  • All Implemented Interfaces:
    java.util.Iterator<T>, PrefetchableIterator<T>
    Enclosing class:
    DataStreams
    public static class DataStreams.DataStreamDecoder<T>
extends java.lang.Object
implements PrefetchableIterator<T>
    An adapter which converts an InputStream to a PrefetchableIterator of T values using the specified Coder.

    Note that this adapter follows the Beam Fn API specification for forcing values that decode consuming zero bytes to consuming exactly one byte.

    Note that access to the underlying InputStream is lazy and will only be invoked on first access to next(), hasNext(), isReady(), and prefetch().

    Note that isReady() and prefetch() rely on non-empty ByteStrings being returned via the underlying PrefetchableIterator otherwise the prefetch() will seemingly make zero progress yet will actually advance through the empty pages.

    • Constructor Summary

      Constructors 
      Constructor Description
      DataStreamDecoder​(org.apache.beam.sdk.coders.Coder<T> coder, PrefetchableIterator<org.apache.beam.vendor.grpc.v1p48p1.com.google.protobuf.ByteString> inputStream)  

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.util.List<T> decodeFromChunkBoundaryToChunkBoundary()
      Skips any remaining bytes in the current ByteString moving to the next ByteString in the underlying ByteString iterator and decoding elements till at the next boundary.
      boolean hasNext()  
      boolean isReady()
      Returns true if and only if Iterator.hasNext() and Iterator.next() will not require an expensive operation.
      T next()  
      void prefetch()
      If not PrefetchableIterator.isReady(), schedules the next expensive operation such that at some point in time in the future PrefetchableIterator.isReady() will return true.
      void remove()  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

      • Methods inherited from interface java.util.Iterator

        forEachRemaining

    • Constructor Detail

      • DataStreamDecoder

        public DataStreamDecoder​(org.apache.beam.sdk.coders.Coder<T> coder,
                         PrefetchableIterator<org.apache.beam.vendor.grpc.v1p48p1.com.google.protobuf.ByteString> inputStream)

    • Method Detail

      • decodeFromChunkBoundaryToChunkBoundary

        public java.util.List<T> decodeFromChunkBoundaryToChunkBoundary()
        Skips any remaining bytes in the current ByteString moving to the next ByteString in the underlying ByteString iterator and decoding elements till at the next boundary.

      • isReady

        public boolean isReady()
        Description copied from interface: PrefetchableIterator
        Returns true if and only if Iterator.hasNext() and Iterator.next() will not require an expensive operation.
        Specified by:
        isReady in interface PrefetchableIterator<T>

      • hasNext

        public boolean hasNext()
        Specified by:
        hasNext in interface java.util.Iterator<T>

      • next

        public T next()
        Specified by:
        next in interface java.util.Iterator<T>

      • remove

        public void remove()
        Specified by:
        remove in interface java.util.Iterator<T>