Java Writer.getRawLength方法代码示例

import org.apache.hadoop.mapred.IFile.Writer; //导入方法依赖的package包/类
@Override
public void merge(List<CompressAwarePath> inputs) throws IOException {
  // sanity check
  if (inputs == null || inputs.isEmpty()) {
    LOG.info("No ondisk files to merge...");
    return;
  }
  
  long approxOutputSize = 0;
  int bytesPerSum = 
    jobConf.getInt("io.bytes.per.checksum", 512);
  
  LOG.info("OnDiskMerger: We have  " + inputs.size() + 
           " map outputs on disk. Triggering merge...");
  
  // 1. Prepare the list of files to be merged. 
  for (CompressAwarePath file : inputs) {
    approxOutputSize += localFS.getFileStatus(file).getLen();
  }

  // add the checksum length
  approxOutputSize += 
    ChecksumFileSystem.getChecksumLength(approxOutputSize, bytesPerSum);

  // 2. Start the on-disk merge process
  Path outputPath = 
    localDirAllocator.getLocalPathForWrite(inputs.get(0).toString(), 
        approxOutputSize, jobConf).suffix(Task.MERGED_OUTPUT_PREFIX);

  FSDataOutputStream out = CryptoUtils.wrapIfNecessary(jobConf, rfs.create(outputPath));
  Writer<K, V> writer = new Writer<K, V>(jobConf, out,
      (Class<K>) jobConf.getMapOutputKeyClass(),
      (Class<V>) jobConf.getMapOutputValueClass(), codec, null, true);

  RawKeyValueIterator iter  = null;
  CompressAwarePath compressAwarePath;
  Path tmpDir = new Path(reduceId.toString());
  try {
    iter = Merger.merge(jobConf, rfs,
                        (Class<K>) jobConf.getMapOutputKeyClass(),
                        (Class<V>) jobConf.getMapOutputValueClass(),
                        codec, inputs.toArray(new Path[inputs.size()]), 
                        true, ioSortFactor, tmpDir, 
                        (RawComparator<K>) jobConf.getOutputKeyComparator(), 
                        reporter, spilledRecordsCounter, null, 
                        mergedMapOutputsCounter, null);

    Merger.writeFile(iter, writer, reporter, jobConf);
    writer.close();
    compressAwarePath = new CompressAwarePath(outputPath,
        writer.getRawLength(), writer.getCompressedLength());
  } catch (IOException e) {
    localFS.delete(outputPath, true);
    throw e;
  }

  closeOnDiskFile(compressAwarePath);

  LOG.info(reduceId +
      " Finished merging " + inputs.size() + 
      " map output files on disk of total-size " + 
      approxOutputSize + "." + 
      " Local output file is " + outputPath + " of size " +
      localFS.getFileStatus(outputPath).getLen());
}
 

import org.apache.hadoop.mapred.IFile.Writer; //导入方法依赖的package包/类
@Override
public void merge(List<InMemoryMapOutput<K,V>> inputs) throws IOException {
  if (inputs == null || inputs.size() == 0) {
    return;
  }
  
  //name this output file same as the name of the first file that is 
  //there in the current list of inmem files (this is guaranteed to
  //be absent on the disk currently. So we don't overwrite a prev. 
  //created spill). Also we need to create the output file now since
  //it is not guaranteed that this file will be present after merge
  //is called (we delete empty files as soon as we see them
  //in the merge method)

  //figure out the mapId 
  TaskAttemptID mapId = inputs.get(0).getMapId();
  TaskID mapTaskId = mapId.getTaskID();

  List<Segment<K, V>> inMemorySegments = new ArrayList<Segment<K, V>>();
  long mergeOutputSize = 
    createInMemorySegments(inputs, inMemorySegments,0);
  int noInMemorySegments = inMemorySegments.size();

  Path outputPath = 
    mapOutputFile.getInputFileForWrite(mapTaskId,
                                       mergeOutputSize).suffix(
                                           Task.MERGED_OUTPUT_PREFIX);

  FSDataOutputStream out = CryptoUtils.wrapIfNecessary(jobConf, rfs.create(outputPath));
  Writer<K, V> writer = new Writer<K, V>(jobConf, out,
      (Class<K>) jobConf.getMapOutputKeyClass(),
      (Class<V>) jobConf.getMapOutputValueClass(), codec, null, true);

  RawKeyValueIterator rIter = null;
  CompressAwarePath compressAwarePath;
  try {
    LOG.info("Initiating in-memory merge with " + noInMemorySegments + 
             " segments...");
    
    rIter = Merger.merge(jobConf, rfs,
                         (Class<K>)jobConf.getMapOutputKeyClass(),
                         (Class<V>)jobConf.getMapOutputValueClass(),
                         inMemorySegments, inMemorySegments.size(),
                         new Path(reduceId.toString()),
                         (RawComparator<K>)jobConf.getOutputKeyComparator(),
                         reporter, spilledRecordsCounter, null, null);
    
    if (null == combinerClass) {
      Merger.writeFile(rIter, writer, reporter, jobConf);
    } else {
      combineCollector.setWriter(writer);
      combineAndSpill(rIter, reduceCombineInputCounter);
    }
    writer.close();
    compressAwarePath = new CompressAwarePath(outputPath,
        writer.getRawLength(), writer.getCompressedLength());

    LOG.info(reduceId +  
        " Merge of the " + noInMemorySegments +
        " files in-memory complete." +
        " Local file is " + outputPath + " of size " + 
        localFS.getFileStatus(outputPath).getLen());
  } catch (IOException e) { 
    //make sure that we delete the ondisk file that we created 
    //earlier when we invoked cloneFileAttributes
    localFS.delete(outputPath, true);
    throw e;
  }

  // Note the output of the merge
  closeOnDiskFile(compressAwarePath);
}
 

import org.apache.hadoop.mapred.IFile.Writer; //导入方法依赖的package包/类
@Override
public void merge(List<InMemoryMapOutput<K,V>> inputs) throws IOException {
  if (inputs == null || inputs.size() == 0) {
    return;
  }
  
  //name this output file same as the name of the first file that is 
  //there in the current list of inmem files (this is guaranteed to
  //be absent on the disk currently. So we don't overwrite a prev. 
  //created spill). Also we need to create the output file now since
  //it is not guaranteed that this file will be present after merge
  //is called (we delete empty files as soon as we see them
  //in the merge method)

  //figure out the mapId 
  TaskAttemptID mapId = inputs.get(0).getMapId();
  TaskID mapTaskId = mapId.getTaskID();

  List<Segment<K, V>> inMemorySegments = new ArrayList<Segment<K, V>>();
  long mergeOutputSize = 
    createInMemorySegments(inputs, inMemorySegments,0);
  int noInMemorySegments = inMemorySegments.size();

  Path outputPath = 
    mapOutputFile.getInputFileForWrite(mapTaskId,
                                       mergeOutputSize).suffix(
                                           Task.MERGED_OUTPUT_PREFIX);

  Writer<K,V> writer = 
    new Writer<K,V>(jobConf, rfs, outputPath,
                    (Class<K>) jobConf.getMapOutputKeyClass(),
                    (Class<V>) jobConf.getMapOutputValueClass(),
                    codec, null);

  RawKeyValueIterator rIter = null;
  CompressAwarePath compressAwarePath;
  try {
    LOG.info("Initiating in-memory merge with " + noInMemorySegments + 
             " segments...");
    
    rIter = Merger.merge(jobConf, rfs,
                         (Class<K>)jobConf.getMapOutputKeyClass(),
                         (Class<V>)jobConf.getMapOutputValueClass(),
                         inMemorySegments, inMemorySegments.size(),
                         new Path(reduceId.toString()),
                         (RawComparator<K>)jobConf.getOutputKeyComparator(),
                         reporter, spilledRecordsCounter, null, null);
    
    if (null == combinerClass) {
      Merger.writeFile(rIter, writer, reporter, jobConf);
    } else {
      combineCollector.setWriter(writer);
      combineAndSpill(rIter, reduceCombineInputCounter);
    }
    writer.close();
    compressAwarePath = new CompressAwarePath(outputPath,
        writer.getRawLength(), writer.getCompressedLength());

    LOG.info(reduceId +  
        " Merge of the " + noInMemorySegments +
        " files in-memory complete." +
        " Local file is " + outputPath + " of size " + 
        localFS.getFileStatus(outputPath).getLen());
  } catch (IOException e) { 
    //make sure that we delete the ondisk file that we created 
    //earlier when we invoked cloneFileAttributes
    localFS.delete(outputPath, true);
    throw e;
  }

  // Note the output of the merge
  closeOnDiskFile(compressAwarePath);
}