| /* |
| * Copyright 2009-2010 by The Regents of the University of California |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * you may obtain a copy of the License from |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package edu.uci.ics.pregelix.dataflow; |
| |
| import java.nio.ByteBuffer; |
| |
| import edu.uci.ics.hyracks.api.context.IHyracksTaskContext; |
| import edu.uci.ics.hyracks.api.dataflow.IOperatorNodePushable; |
| import edu.uci.ics.hyracks.api.dataflow.value.IRecordDescriptorProvider; |
| import edu.uci.ics.hyracks.api.exceptions.HyracksDataException; |
| import edu.uci.ics.hyracks.api.job.JobSpecification; |
| import edu.uci.ics.hyracks.dataflow.common.comm.io.ArrayTupleBuilder; |
| import edu.uci.ics.hyracks.dataflow.common.comm.io.FrameTupleAppender; |
| import edu.uci.ics.hyracks.dataflow.common.comm.util.FrameUtils; |
| import edu.uci.ics.hyracks.dataflow.std.base.AbstractSingleActivityOperatorDescriptor; |
| import edu.uci.ics.hyracks.dataflow.std.base.AbstractUnaryOutputSourceOperatorNodePushable; |
| |
| public class EmptyTupleSourceOperatorDescriptor extends AbstractSingleActivityOperatorDescriptor { |
| private static final long serialVersionUID = 1L; |
| |
| public EmptyTupleSourceOperatorDescriptor(JobSpecification spec) { |
| super(spec, 0, 1); |
| } |
| |
| @Override |
| public IOperatorNodePushable createPushRuntime(final IHyracksTaskContext ctx, |
| IRecordDescriptorProvider recordDescProvider, int partition, int nPartitions) throws HyracksDataException { |
| return new AbstractUnaryOutputSourceOperatorNodePushable() { |
| private ByteBuffer frame = ctx.allocateFrame(); |
| private ArrayTupleBuilder tb = new ArrayTupleBuilder(0); |
| private FrameTupleAppender appender = new FrameTupleAppender(ctx.getFrameSize()); |
| |
| @Override |
| public void initialize() throws HyracksDataException { |
| try { |
| writer.open(); |
| appender.reset(frame, true); |
| if (!appender.append(tb.getFieldEndOffsets(), tb.getByteArray(), 0, tb.getSize())) { |
| throw new IllegalStateException(); |
| } |
| FrameUtils.flushFrame(frame, writer); |
| writer.close(); |
| } catch (Exception e) { |
| throw new HyracksDataException(e); |
| } |
| } |
| }; |
| } |
| |
| } |