Package org.apache.flink.streaming.api.functions.source.legacy

Class FromElementsFunction<T>

java.lang.Object
org.apache.flink.streaming.api.functions.source.legacy.FromElementsFunction<T>
Type Parameters:
T - The type of elements returned by this function.
All Implemented Interfaces:
Serializable, org.apache.flink.api.common.functions.Function, CheckpointedFunction, SourceFunction<T>, LineageVertexProvider, org.apache.flink.streaming.api.operators.OutputTypeConfigurable<T>
@Internal public class FromElementsFunction<T> extends Object implements SourceFunction<T>, CheckpointedFunction, org.apache.flink.streaming.api.operators.OutputTypeConfigurable<T>, LineageVertexProvider
Deprecated.
This class is based on the SourceFunction API, which is due to be removed. Use the new Source API instead.
A stream source function that returns a sequence of elements.

This source function serializes the elements using Flink's type information. That way, any object transport using Java serialization will not be affected by the serializability of the elements.

NOTE: This source has a parallelism of 1.

See Also:

  • Constructor Details

    • FromElementsFunction

      @SafeVarargs public FromElementsFunction(org.apache.flink.api.common.typeutils.TypeSerializer<T> serializer, T... elements) throws IOException
      Deprecated.
      Throws:
      IOException

    • FromElementsFunction

      public FromElementsFunction(org.apache.flink.api.common.typeutils.TypeSerializer<T> serializer, Iterable<T> elements) throws IOException
      Deprecated.
      Throws:
      IOException

    • FromElementsFunction

      @SafeVarargs public FromElementsFunction(T... elements)
      Deprecated.

    • FromElementsFunction

      public FromElementsFunction(Iterable<T> elements)
      Deprecated.

  • Method Details

    • getSerializer

      @VisibleForTesting @Nullable public org.apache.flink.api.common.typeutils.TypeSerializer<T> getSerializer()
      Deprecated.

    • setOutputType

      public void setOutputType(org.apache.flink.api.common.typeinfo.TypeInformation<T> outTypeInfo, org.apache.flink.api.common.ExecutionConfig executionConfig)
      Deprecated.
      Set element type and re-serialize element if required. Should only be called before serialization/deserialization of this function.
      Specified by:
      setOutputType in interface org.apache.flink.streaming.api.operators.OutputTypeConfigurable<T>

    • initializeState

      public void initializeState(FunctionInitializationContext context) throws Exception
      Deprecated.
      Description copied from interface: CheckpointedFunction
      This method is called when the parallel function instance is created during distributed execution. Functions typically set up their state storing data structures in this method.
      Specified by:
      initializeState in interface CheckpointedFunction
      Parameters:
      context - the context for initializing the operator
      Throws:
      Exception - Thrown, if state could not be created ot restored.

    • run

      public void run(SourceFunction.SourceContext<T> ctx) throws Exception
      Deprecated.
      Description copied from interface: SourceFunction
      Starts the source. Implementations use the SourceFunction.SourceContext to emit elements. Sources that checkpoint their state for fault tolerance should use the checkpoint lock to ensure consistency between the bookkeeping and emitting the elements.

      Sources that implement CheckpointedFunction must lock on the checkpoint lock checkpoint lock (using a synchronized block) before updating internal state and emitting elements, to make both an atomic operation.

      Refer to the top-level class docs for an example.

      Specified by:
      run in interface SourceFunction<T>
      Parameters:
      ctx - The context to emit elements to and for accessing locks.
      Throws:
      Exception

    • cancel

      public void cancel()
      Deprecated.
      Description copied from interface: SourceFunction
      Cancels the source. Most sources will have a while loop inside the SourceFunction.run(SourceContext) method. The implementation needs to ensure that the source will break out of that loop after this method is called.

      A typical pattern is to have an "volatile boolean isRunning" flag that is set to false in this method. That flag is checked in the loop condition.

      In case of an ungraceful shutdown (cancellation of the source operator, possibly for failover), the thread that calls SourceFunction.run(SourceContext) will also be interrupted) by the Flink runtime, in order to speed up the cancellation (to ensure threads exit blocking methods fast, like I/O, blocking queues, etc.). The interruption happens strictly after this method has been called, so any interruption handler can rely on the fact that this method has completed (for example to ignore exceptions that happen after cancellation).

      During graceful shutdown (for example stopping a job with a savepoint), the program must cleanly exit the SourceFunction.run(SourceContext) method soon after this method was called. The Flink runtime will NOT interrupt the source thread during graceful shutdown. Source implementors must ensure that no thread interruption happens on any thread that emits records through the SourceContext from the SourceFunction.run(SourceContext) method; otherwise the clean shutdown may fail when threads are interrupted while processing the final records.

      Because the SourceFunction cannot easily differentiate whether the shutdown should be graceful or ungraceful, we recommend that implementors refrain from interrupting any threads that interact with the SourceContext at all. You can rely on the Flink runtime to interrupt the source thread in case of ungraceful cancellation. Any additionally spawned threads that directly emit records through the SourceContext should use a shutdown method that does not rely on thread interruption.

      Specified by:
      cancel in interface SourceFunction<T>

    • getNumElements

      public int getNumElements()
      Deprecated.
      Gets the number of elements produced in total by this function.
      Returns:
      The number of elements produced in total.

    • getNumElementsEmitted

      public int getNumElementsEmitted()
      Deprecated.
      Gets the number of elements emitted so far.
      Returns:
      The number of elements emitted so far.

    • snapshotState

      public void snapshotState(FunctionSnapshotContext context) throws Exception
      Deprecated.
      Description copied from interface: CheckpointedFunction
      This method is called when a snapshot for a checkpoint is requested. This acts as a hook to the function to ensure that all state is exposed by means previously offered through FunctionInitializationContext when the Function was initialized, or offered now by FunctionSnapshotContext itself.
      Specified by:
      snapshotState in interface CheckpointedFunction
      Parameters:
      context - the context for drawing a snapshot of the operator
      Throws:
      Exception - Thrown, if state could not be created ot restored.

    • checkCollection

      public static <OUT> void checkCollection(Collection<OUT> elements, Class<OUT> viewedAs)
      Deprecated.
      Verifies that all elements in the collection are non-null, and are of the given class, or a subclass thereof.
      Type Parameters:
      OUT - The generic type of the collection to be checked.
      Parameters:
      elements - The collection to check.
      viewedAs - The class to which the elements must be assignable to.

    • getLineageVertex

      public LineageVertex getLineageVertex()
      Deprecated.
      Specified by:
      getLineageVertex in interface LineageVertexProvider