[beargan]

Sink

public class MySink extends AbstractSink implements Configurable {
  private String myProp;

  @Override
  public void configure(Context context) {
    String myProp = context.getString("myProp", "defaultValue");

    // Process the myProp value (e.g. validation)

    // Store myProp for later retrieval by process() method
    this.myProp = myProp;
  }

  @Override
  public void start() {
    // Initialize the connection to the external repository (e.g. HDFS) that
    // this Sink will forward Events to ..
  }

  @Override
  public void stop () {
    // Disconnect from the external respository and do any
    // additional cleanup (e.g. releasing resources or nulling-out
    // field values) ..
  }

  @Override
  public Status process() throws EventDeliveryException {
    Status status = null;

    // Start transaction
    Channel ch = getChannel();
    Transaction txn = ch.getTransaction();
    txn.begin();
    try {
      // This try clause includes whatever Channel operations you want to do

      Event event = ch.take();

      // Send the Event to the external repository.
      // storeSomeData(e);

      txn.commit();
      status = Status.READY;
    } catch (Throwable t) {
      txn.rollback();

      // Log exception, handle individual exceptions as needed

      status = Status.BACKOFF;

      // re-throw all Errors
      if (t instanceof Error) {
        throw (Error)t;
      }
    }
    return status;
  }
}

Compile and execute the following error:

2015-11-22 15:30:58,773 (SinkRunner-PollingRunner-DefaultSinkProcessor) [ERROR 
- org.apache.flume.SinkRunner$PollingRunner.run(SinkRunner.java:160)] Unable to 
deliver event. Exception follows.
java.lang.IllegalStateException: begin() called when transaction is COMPLETED!
        at 
com.google.common.base.Preconditions.checkState(Preconditions.java:145)
        at 
org.apache.flume.channel.BasicTransactionSemantics.begin(BasicTransactionSemantics.java:131)
        at Toturial.Flume.MySink.process(MySink.java:54)
        at 
org.apache.flume.sink.DefaultSinkProcessor.process(DefaultSinkProcessor.java:68)
        at org.apache.flume.SinkRunner$PollingRunner.run(SinkRunner.java:147)
        at java.lang.Thread.run(Unknown Source)