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

Class DataGeneratorSource<T>

    • Constructor Detail

      • DataGeneratorSource

        public DataGeneratorSource​(DataGenerator<T> generator)
        Deprecated.
        Creates a source that emits records by DataGenerator without controlling emit rate.
        Parameters:
        generator - data generator.

      • DataGeneratorSource

        public DataGeneratorSource​(DataGenerator<T> generator,
                           long rowsPerSecond,
                           @Nullable
                           Long numberOfRows)
        Deprecated.
        Creates a source that emits records by DataGenerator.
        Parameters:
        generator - data generator.
        rowsPerSecond - Control the emit rate.
        numberOfRows - Total number of rows to output.

    • Method Detail

      • open

        public void open​(OpenContext openContext)
          throws Exception
        Deprecated.
        Description copied from interface: RichFunction
        Initialization method for the function. It is called before the actual working methods (like map or join) and thus suitable for one time setup work. For functions that are part of an iteration, this method will be invoked at the beginning of each iteration superstep.

        The openContext object passed to the function can be used for configuration and initialization. The openContext contains some necessary information that were configured on the function in the program composition. 

        
 public class MyFilter extends RichFilterFunction<String> {

     private String searchString;

     public void open(OpenContext openContext) {
         // initialize the value of searchString
     }

     public boolean filter(String value) {
         return value.equals(searchString);
     }
 }
        Specified by:
        open in interface RichFunction
        Overrides:
        open in class AbstractRichFunction
        Parameters:
        openContext - The context containing information about the context in which the function is opened.
        Throws:
        Exception - Implementations may forward exceptions, which are caught by the runtime. When the runtime catches an exception, it aborts the task and lets the fail-over logic decide whether to retry the task execution.

      • 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.

      • close

        public void close()
           throws Exception
        Deprecated.
        Description copied from interface: RichFunction
        Tear-down method for the user code. It is called after the last call to the main working methods (e.g. map or join). For functions that are part of an iteration, this method will be invoked after each iteration superstep.

        This method can be used for clean up work.

        Specified by:
        close in interface RichFunction
        Overrides:
        close in class AbstractRichFunction
        Throws:
        Exception - Implementations may forward exceptions, which are caught by the runtime. When the runtime catches an exception, it aborts the task and lets the fail-over logic decide whether to retry the task execution.

      • 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>