Package org.apache.beam.sdk.coders

Class DoubleCoder

java.lang.Object
org.apache.beam.sdk.coders.Coder<Double>
org.apache.beam.sdk.coders.StructuredCoder<Double>
org.apache.beam.sdk.coders.AtomicCoder<Double>
org.apache.beam.sdk.coders.DoubleCoder
All Implemented Interfaces:
Serializable
public class DoubleCoder extends AtomicCoder<Double>
A DoubleCoder encodes Double values in 8 bytes using Java serialization.
See Also:

  • Method Details

    • of

      public static DoubleCoder of()

    • encode

      public void encode(Double value, OutputStream outStream) throws IOException, CoderException
      Description copied from class: Coder
      Encodes the given value of type T onto the given output stream. Multiple elements can be encoded next to each other on the output stream, each coder should encode information to know how many bytes to read when decoding. A common approach is to prefix the encoding with the element's encoded length.
      Specified by:
      encode in class Coder<Double>
      Throws:
      IOException - if writing to the OutputStream fails for some reason
      CoderException - if the value could not be encoded for some reason

    • decode

      public Double decode(InputStream inStream) throws IOException, CoderException
      Description copied from class: Coder
      Decodes a value of type T from the given input stream in the given context. Returns the decoded value. Multiple elements can be encoded next to each other on the input stream, each coder should encode information to know how many bytes to read when decoding. A common approach is to prefix the encoding with the element's encoded length.
      Specified by:
      decode in class Coder<Double>
      Throws:
      IOException - if reading from the InputStream fails for some reason
      CoderException - if the value could not be decoded for some reason

    • verifyDeterministic

      public void verifyDeterministic() throws Coder.NonDeterministicException
      Throw Coder.NonDeterministicException if the coding is not deterministic.

      In order for a Coder to be considered deterministic, the following must be true:

      • two values that compare as equal (via Object.equals() or Comparable.compareTo(), if supported) have the same encoding.
      • the Coder always produces a canonical encoding, which is the same for an instance of an object even if produced on different computers at different times.
      .

      Unless overridden, does not throw. An AtomicCoder is presumed to be deterministic

      Overrides:
      verifyDeterministic in class AtomicCoder<Double>
      Throws:
      Coder.NonDeterministicException - always. Floating-point operations are not guaranteed to be deterministic, even if the storage format might be, so floating point representations are not recommended for use in operations that require deterministic inputs.

    • consistentWithEquals

      public boolean consistentWithEquals()
      Returns true if this Coder is injective with respect to Object.equals(java.lang.Object).

      Whenever the encoded bytes of two values are equal, then the original values are equal according to Objects.equals(). Note that this is well-defined for null.

      This condition is most notably false for arrays. More generally, this condition is false whenever equals() compares object identity, rather than performing a semantic/structural comparison.

      By default, returns false.

      Overrides:
      consistentWithEquals in class Coder<Double>
      Returns:
      true. This coder is injective.

    • isRegisterByteSizeObserverCheap

      public boolean isRegisterByteSizeObserverCheap(Double value)
      Returns whether Coder.registerByteSizeObserver(T, org.apache.beam.sdk.util.common.ElementByteSizeObserver) cheap enough to call for every element, that is, if this Coder can calculate the byte size of the element to be coded in roughly constant time (or lazily).

      Not intended to be called by user code, but instead by PipelineRunner implementations.

      By default, returns false. The default Coder.registerByteSizeObserver(T, org.apache.beam.sdk.util.common.ElementByteSizeObserver) implementation invokes Coder.getEncodedElementByteSize(T) which requires re-encoding an element unless it is overridden. This is considered expensive.

      Overrides:
      isRegisterByteSizeObserverCheap in class Coder<Double>
      Returns:
      true. getEncodedElementByteSize(java.lang.Double) returns a constant.

    • getEncodedTypeDescriptor

      public TypeDescriptor<Double> getEncodedTypeDescriptor()
      Description copied from class: Coder
      Returns the TypeDescriptor for the type encoded.
      Overrides:
      getEncodedTypeDescriptor in class Coder<Double>

    • getEncodedElementByteSize

      protected long getEncodedElementByteSize(Double value) throws Exception
      Returns the size in bytes of the encoded value using this coder.
      Overrides:
      getEncodedElementByteSize in class Coder<Double>
      Returns:
      8, the byte size of a Double encoded using Java serialization.
      Throws:
      Exception