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From: yogidevendra <git@git.apache.org>
To: dev@apex.incubator.apache.org
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References: <git-pr-326-apex-malhar@git.apache.org>
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Subject: [GitHub] apex-malhar pull request #326: APEXMALHAR-2116 Added FS record reader operat...
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Message-Id: <20160630104610.AE63CDFF03@git1-us-west.apache.org>
Date: Thu, 30 Jun 2016 10:46:10 +0000 (UTC)
archived-at: Thu, 30 Jun 2016 10:46:17 -0000

Github user yogidevendra commented on a diff in the pull request:

    https://github.com/apache/apex-malhar/pull/326#discussion_r69111489
  
    --- Diff: library/src/main/java/org/apache/apex/malhar/lib/fs/FSRecordReaderModule.java ---
    @@ -0,0 +1,332 @@
    +/**
    + * Licensed to the Apache Software Foundation (ASF) under one
    + * or more contributor license agreements.  See the NOTICE file
    + * distributed with this work for additional information
    + * regarding copyright ownership.  The ASF licenses this file
    + * to you 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 at
    + *
    + *   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 org.apache.apex.malhar.lib.fs;
    +
    +import javax.validation.constraints.Min;
    +
    +import javax.validation.constraints.NotNull;
    +import javax.validation.constraints.Size;
    +
    +import org.apache.apex.malhar.lib.fs.FSRecordReader.RECORD_READER_MODE;
    +import org.apache.hadoop.conf.Configuration;
    +
    +import com.datatorrent.api.Context;
    +import com.datatorrent.api.DAG;
    +import com.datatorrent.api.Module;
    +import com.datatorrent.common.partitioner.StatelessPartitioner;
    +import com.datatorrent.lib.codec.KryoSerializableStreamCodec;
    +import com.datatorrent.lib.io.block.BlockMetadata;
    +import com.datatorrent.lib.io.block.FSSliceReader;
    +import com.datatorrent.lib.io.fs.FileSplitterInput;
    +
    +/**
    + * This module is used for reading records/tuples from FileSystem. Records can
    + * be read in parallel using multiple partitions of record reader operator.
    + * (Ordering is not guaranteed when records are read in parallel)
    + *
    + * Input directory is scanned at specified interval to poll for new data.
    + * 
    + * The module reads data in parallel, following parameters can be configured
    + * <br/>
    + * 1. files: list of file(s)/directories to read<br/>
    + * 2. filePatternRegularExp: Files names matching given regex will be read<br/>
    + * 3. scanIntervalMillis: interval between two scans to discover new files in
    + * input directory<br/>
    + * 4. recursive: if scan recursively input directories<br/>
    + * 5. blockSize: block size used to read input blocks of file<br/>
    + * 6. readersCount: count of readers to read input file<br/>
    + * 7. sequentialFileRead: If emit file blocks in sequence?<br/>
    + * 8. blocksThreshold: number of blocks emitted per window
    + */
    +@org.apache.hadoop.classification.InterfaceStability.Evolving
    +public class FSRecordReaderModule implements Module
    +{
    +  @NotNull
    +  @Size(min = 1)
    +  private String files;
    +  private String filePatternRegularExp;
    +  @Min(0)
    +  private long scanIntervalMillis;
    +  private boolean recursive = true;
    +  private boolean sequentialFileRead = false;
    +  private int readersCount;
    +  @Min(1)
    +  protected int blocksThreshold;
    +
    +  public final transient ProxyOutputPort<byte[]> records = new ProxyOutputPort<byte[]>();
    +
    +  /**
    +   * Criteria for record split
    +   */
    +  private RECORD_READER_MODE mode;
    +
    +  /**
    +   * Length for fixed width record
    +   */
    +  private int recordLength;
    +
    +  public FileSplitterInput createFileSplitter()
    +  {
    +    return new FileSplitterInput();
    +  }
    +
    +  public FSRecordReader createBlockReader()
    +  {
    +    FSRecordReader recordReader = new FSRecordReader();
    +    recordReader.setMode(mode);
    +    recordReader.setRecordLength(recordLength);
    +
    +    return recordReader;
    +  }
    +
    +  @Override
    +  public void populateDAG(DAG dag, Configuration configuration)
    +  {
    +    FileSplitterInput fileSplitter = dag.addOperator("FileSplitter", createFileSplitter());
    +    FSRecordReader recordReader = dag.addOperator("BlockReader", createBlockReader());
    +
    +    dag.addStream("BlockMetadata", fileSplitter.blocksMetadataOutput, recordReader.blocksMetadataInput);
    +
    +    if (sequentialFileRead) {
    +      dag.setInputPortAttribute(recordReader.blocksMetadataInput, Context.PortContext.STREAM_CODEC,
    +          new SequentialFileBlockMetadataCodec());
    +    }
    +
    +    FileSplitterInput.TimeBasedDirectoryScanner fileScanner = fileSplitter.getScanner();
    +    fileScanner.setFiles(files);
    +    if (scanIntervalMillis != 0) {
    +      fileScanner.setScanIntervalMillis(scanIntervalMillis);
    +    }
    +    fileScanner.setRecursive(recursive);
    +    if (filePatternRegularExp != null) {
    +      fileSplitter.getScanner().setFilePatternRegularExp(filePatternRegularExp);
    +    }
    +
    +    recordReader.setBasePath(files);
    +    if (readersCount != 0) {
    +      dag.setAttribute(recordReader, Context.OperatorContext.PARTITIONER,
    +          new StatelessPartitioner<FSSliceReader>(readersCount));
    +    }
    +    fileSplitter.setBlocksThreshold(blocksThreshold);
    +    records.set(recordReader.records);
    +  }
    +
    +  /**
    +   * A comma separated list of directories to scan. If the path is not fully
    +   * qualified the default file system is used. A fully qualified path can be
    +   * provided to scan directories in other filesystems.
    +   *
    +   * @param files
    +   *          files
    +   */
    +  public void setFiles(String files)
    +  {
    +    this.files = files;
    --- End diff --
    
    I tried to keep it consistent with FSInputModule.java. If you feel that readability/intuitive names are more important than having consistency across operators then I am fine with changing this field name.


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