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

Class FileSourceFunction<OUT>

java.lang.Object

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

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

org.apache.flink.streaming.api.functions.source.FileSourceFunction<OUT>

All Implemented Interfaces:

Serializable, org.apache.flink.api.common.functions.Function, org.apache.flink.api.common.functions.RichFunction, ParallelSourceFunction<OUT>, SourceFunction<OUT>

@PublicEvolving
public class FileSourceFunction<OUT>
extends RichParallelSourceFunction<OUT>

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
FileSourceFunction(org.apache.flink.api.common.io.InputFormat<OUT,?> format, org.apache.flink.api.common.typeinfo.TypeInformation<OUT> typeInfo)

Method Summary

Modifier and Type	Method and Description
void	cancel() Cancels the source.
void	close()
org.apache.flink.api.common.io.InputFormat<OUT,org.apache.flink.core.io.InputSplit>	getFormat() Returns the InputFormat.
void	open(org.apache.flink.configuration.Configuration parameters)
void	run(SourceFunction.SourceContext<OUT> ctx) Starts the source.

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

getIterationRuntimeContext, getRuntimeContext, setRuntimeContext

Methods inherited from class java.lang.Object

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

Constructor Detail

FileSourceFunction

public FileSourceFunction(org.apache.flink.api.common.io.InputFormat<OUT,?> format,
                          org.apache.flink.api.common.typeinfo.TypeInformation<OUT> typeInfo)

Method Detail

open

public void open(org.apache.flink.configuration.Configuration parameters)
          throws Exception

Specified by:

open in interface org.apache.flink.api.common.functions.RichFunction

Overrides:

open in class org.apache.flink.api.common.functions.AbstractRichFunction

Throws:

Exception

close

public void close()
           throws Exception

Specified by:

close in interface org.apache.flink.api.common.functions.RichFunction

Overrides:

close in class org.apache.flink.api.common.functions.AbstractRichFunction

Throws:

Exception

run

public void run(SourceFunction.SourceContext<OUT> 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.

getFormat

public org.apache.flink.api.common.io.InputFormat<OUT,org.apache.flink.core.io.InputSplit> getFormat()

Returns the InputFormat. This is only needed because we need to set the input split assigner on the StreamGraph.