org.apache.crunch.io.impl.ReadableDataImpl.java Source code

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Here is the source code for org.apache.crunch.io.impl.ReadableDataImpl.java

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/**
 * 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.impl;

import com.google.common.base.Function;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import org.apache.crunch.CrunchRuntimeException;
import org.apache.crunch.DoFn;
import org.apache.crunch.ReadableData;
import org.apache.crunch.SourceTarget;
import org.apache.crunch.io.CompositePathIterable;
import org.apache.crunch.io.FileReaderFactory;
import org.apache.crunch.util.DistCache;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapreduce.TaskInputOutputContext;

import javax.annotation.Nullable;
import java.io.IOException;
import java.util.List;
import java.util.Set;

public abstract class ReadableDataImpl<T> implements ReadableData<T> {

    private List<String> paths;
    private transient SourceTarget parent;

    protected ReadableDataImpl(List<Path> paths) {
        this.paths = Lists.newArrayList();
        for (Path p : paths) {
            this.paths.add(p.toString());
        }
    }

    public ReadableData<T> setParent(SourceTarget<?> parent) {
        this.parent = parent;
        return this;
    }

    @Override
    public Set<SourceTarget<?>> getSourceTargets() {
        if (parent != null) {
            return ImmutableSet.<SourceTarget<?>>of(parent);
        } else {
            return ImmutableSet.of();
        }
    }

    @Override
    public void configure(Configuration conf) {
        for (String path : paths) {
            DistCache.addCacheFile(new Path(path), conf);
        }
    }

    protected abstract FileReaderFactory<T> getFileReaderFactory();

    private Path getCacheFilePath(String input, Configuration conf) {
        Path local = DistCache.getPathToCacheFile(new Path(input), conf);
        if (local == null) {
            throw new CrunchRuntimeException("Can't find local cache file for '" + input + "'");
        }
        return local;
    }

    @Override
    public Iterable<T> read(TaskInputOutputContext<?, ?, ?, ?> ctxt) throws IOException {
        final Configuration conf = ctxt.getConfiguration();
        final FileReaderFactory<T> readerFactory = getFileReaderFactory();
        return Iterables.concat(Lists.transform(paths, new Function<String, Iterable<T>>() {
            @Override
            public Iterable<T> apply(@Nullable String input) {
                Path path = getCacheFilePath(input, conf);
                try {
                    FileSystem fs = path.getFileSystem(conf);
                    return CompositePathIterable.create(fs, path, readerFactory);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
        }));
    }
}