| /** |
| * 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.crunch.io.seq; |
| |
| import java.io.IOException; |
| import java.util.Iterator; |
| |
| import org.apache.crunch.MapFn; |
| import org.apache.crunch.io.FileReaderFactory; |
| import org.apache.crunch.io.impl.AutoClosingIterator; |
| import org.apache.crunch.types.Converter; |
| import org.apache.crunch.types.PTableType; |
| import org.apache.crunch.types.PType; |
| import org.apache.crunch.types.writable.Writables; |
| import org.apache.hadoop.fs.FileSystem; |
| import org.apache.hadoop.fs.Path; |
| import org.apache.hadoop.io.NullWritable; |
| import org.apache.hadoop.io.SequenceFile; |
| import org.apache.hadoop.io.Writable; |
| import org.apache.hadoop.util.ReflectionUtils; |
| |
| import com.google.common.collect.Iterators; |
| import com.google.common.collect.UnmodifiableIterator; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| public class SeqFileReaderFactory<T> implements FileReaderFactory<T> { |
| |
| private static final Logger LOG = LoggerFactory.getLogger(SeqFileReaderFactory.class); |
| |
| private final Converter converter; |
| private final MapFn<Object, T> mapFn; |
| private final Writable key; |
| private final Writable value; |
| |
| public SeqFileReaderFactory(PType<T> ptype) { |
| this.converter = ptype.getConverter(); |
| this.mapFn = ptype.getInputMapFn(); |
| if (ptype instanceof PTableType) { |
| PTableType ptt = (PTableType) ptype; |
| this.key = SeqFileHelper.newInstance(ptt.getKeyType(), null); |
| this.value = SeqFileHelper.newInstance(ptt.getValueType(), null); |
| } else { |
| this.key = NullWritable.get(); |
| this.value = SeqFileHelper.newInstance(ptype, null); |
| } |
| } |
| |
| public SeqFileReaderFactory(Class clazz) { |
| PType<T> ptype = Writables.writables(clazz); |
| this.converter = ptype.getConverter(); |
| this.mapFn = ptype.getInputMapFn(); |
| this.key = NullWritable.get(); |
| this.value = (Writable) ReflectionUtils.newInstance(clazz, null); |
| } |
| |
| @Override |
| public Iterator<T> read(FileSystem fs, final Path path) { |
| mapFn.initialize(); |
| try { |
| final SequenceFile.Reader reader = new SequenceFile.Reader(fs, path, fs.getConf()); |
| return new AutoClosingIterator<T>(reader, new UnmodifiableIterator<T>() { |
| boolean nextChecked = false; |
| boolean hasNext = false; |
| |
| @Override |
| public boolean hasNext() { |
| if (nextChecked == true) { |
| return hasNext; |
| } |
| try { |
| hasNext = reader.next(key, value); |
| nextChecked = true; |
| return hasNext; |
| } catch (IOException e) { |
| LOG.info("Error reading from path: {}", path, e); |
| return false; |
| } |
| } |
| |
| @Override |
| public T next() { |
| if (!nextChecked && !hasNext()) { |
| return null; |
| } |
| nextChecked = false; |
| return mapFn.map(converter.convertInput(key, value)); |
| } |
| }); |
| } catch (IOException e) { |
| LOG.info("Could not read seqfile at path: {}", path, e); |
| return Iterators.emptyIterator(); |
| } |
| } |
| |
| } |