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

Class FromSplittableIteratorFunction<T>

java.lang.Object

org.apache.flink.api.common.functions.AbstractRichFunction

org.apache.flink.streaming.api.functions.source.RichParallelSourceFunction<T>

org.apache.flink.streaming.api.functions.source.FromSplittableIteratorFunction<T>

All Implemented Interfaces:

Serializable, Function, RichFunction, ParallelSourceFunction<T>, SourceFunction<T>

@PublicEvolving
public class FromSplittableIteratorFunction<T>
extends RichParallelSourceFunction<T>

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.flink.streaming.api.functions.source.SourceFunction

SourceFunction.SourceContext<T>

Constructor Summary

Constructors

Constructor and Description
FromSplittableIteratorFunction(SplittableIterator<T> iterator)

Method Summary

Modifier and Type	Method and Description
void	cancel() Cancels the source.
void	open(Configuration parameters) Initialization method for the function.
void	run(SourceFunction.SourceContext<T> ctx) Starts the source.

Methods inherited from class org.apache.flink.api.common.functions.AbstractRichFunction

close, getIterationRuntimeContext, getRuntimeContext, setRuntimeContext

Methods inherited from class java.lang.Object

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

Constructor Detail

FromSplittableIteratorFunction

public FromSplittableIteratorFunction(SplittableIterator<T> iterator)

Method Detail

open

public void open(Configuration parameters)
          throws Exception

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 configuration object passed to the function can be used for configuration and initialization. The configuration contains all parameters that were configured on the function in the program composition.

 public class MyMapper extends FilterFunction<String> {
 
     private String searchString;
     
     public void open(Configuration parameters) {
         this.searchString = parameters.getString("foo");
     }
     
     public boolean filter(String value) {
         return value.equals(searchString);
     }
 }
 

By default, this method does nothing.

Specified by:

open in interface RichFunction

Overrides:

open in class AbstractRichFunction

Parameters:

parameters - The configuration containing the parameters attached to the contract.

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.

See Also:

Configuration

run

public void run(SourceFunction.SourceContext<T> ctx)
         throws Exception

Description copied from interface: SourceFunction

Starts the source. Implementations can use the SourceFunction.SourceContext emit elements.

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

  public class ExampleSource<T> implements SourceFunction<T>, Checkpointed<Long> {
      private long count = 0L;
      private volatile boolean isRunning = true;

      public void run(SourceContext<T> ctx) {
          while (isRunning && count < 1000) {
              synchronized (ctx.getCheckpointLock()) {
                  ctx.collect(count);
                  count++;
              }
          }
      }

      public void cancel() {
          isRunning = false;
      }

      public Long snapshotState(long checkpointId, long checkpointTimestamp) { return count; }

      public void restoreState(Long state) { this.count = state; }
 }
 

Parameters:

ctx - The context to emit elements to and for accessing locks.

Throws:

Exception

cancel

public void cancel()

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.

When a source is canceled, the executing thread will also be interrupted (via Thread.interrupt()). The interruption happens strictly after this method has been called, so any interruption handler can rely on the fact that this method has completed. It is good practice to make any flags altered by this method "volatile", in order to guarantee the visibility of the effects of this method to any interruption handler.