com.cloudera.cdk.data.filesystem.FileSystemPartitionIterator.java Source code

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Here is the source code for com.cloudera.cdk.data.filesystem.FileSystemPartitionIterator.java

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/*
 * Copyright 2013 Cloudera.
 *
 * 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 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 com.cloudera.cdk.data.filesystem;

import com.cloudera.cdk.data.DatasetException;
import com.cloudera.cdk.data.FieldPartitioner;
import com.cloudera.cdk.data.PartitionStrategy;
import com.cloudera.cdk.data.spi.StorageKey;
import com.cloudera.cdk.data.spi.MarkerRange;
import com.google.common.base.Function;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.collect.Iterators;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

class FileSystemPartitionIterator implements Iterator<StorageKey>, Iterable<StorageKey> {

    private static final Logger logger = LoggerFactory.getLogger(FileSystemPartitionIterator.class);

    private final FileSystem fs;
    private final Path rootDirectory;
    private final Iterator<StorageKey> iterator;

    class FileSystemIterator extends MultiLevelIterator<String> {
        public FileSystemIterator(int depth) throws IOException {
            super(depth);
        }

        @Override
        @SuppressWarnings("unchecked")
        public Iterable<String> getLevel(List<String> current) {
            final Set<String> dirs = Sets.newLinkedHashSet();

            Path dir = rootDirectory;
            for (int i = 0, n = current.size(); i < n; i += 1) {
                dir = new Path(dir, current.get(i));
            }

            try {
                for (FileStatus stat : fs.listStatus(dir, PathFilters.notHidden())) {
                    if (stat.isDirectory()) {
                        // TODO: add a check here for range.couldContain(Marker)
                        dirs.add(stat.getPath().getName());
                    }
                }
            } catch (IOException ex) {
                throw new DatasetException("Cannot list directory:" + dir, ex);
            }

            return dirs;
        }
    }

    /**
     * Predicate to determine whether a {@link com.cloudera.cdk.data.spi.StorageKey} is in a {@link MarkerRange}.
     */
    private static class InRange implements Predicate<StorageKey> {
        private final MarkerRange range;

        public InRange(MarkerRange range) {
            this.range = range;
        }

        @Override
        public boolean apply(StorageKey key) {
            return range.contains(key);
        }
    }

    /**
     * Conversion function to transform a List into a {@link com.cloudera.cdk.data.spi.StorageKey}.
     */
    private static class MakeKey implements Function<List<String>, StorageKey> {
        private final List<FieldPartitioner> partitioners;
        private final StorageKey reusableKey;
        private final PathConversion convert;

        public MakeKey(PartitionStrategy strategy) {
            this.partitioners = strategy.getFieldPartitioners();
            this.reusableKey = new StorageKey(strategy);
            this.convert = new PathConversion();
        }

        @Override
        @SuppressWarnings("unchecked")
        @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "NP_PARAMETER_MUST_BE_NONNULL_BUT_MARKED_AS_NULLABLE", justification = "Non-null @Nullable parameter inherited from Function")
        public StorageKey apply(List<String> dirs) {
            List<Object> values = Lists.newArrayListWithCapacity(dirs.size());
            for (int i = 0, n = partitioners.size(); i < n; i += 1) {
                values.add(convert.valueForDirname(partitioners.get(i), dirs.get(i)));
            }
            reusableKey.replaceValues(values);
            return reusableKey;
        }
    }

    FileSystemPartitionIterator(FileSystem fs, Path root, PartitionStrategy strategy, MarkerRange range)
            throws IOException {
        Preconditions.checkArgument(fs.isDirectory(root));
        this.fs = fs;
        this.rootDirectory = root;
        this.iterator = Iterators.filter(Iterators
                .transform(new FileSystemIterator(strategy.getFieldPartitioners().size()), new MakeKey(strategy)),
                new InRange(range));
    }

    @Override
    public boolean hasNext() {
        return iterator.hasNext();
    }

    @Override
    public StorageKey next() {
        return iterator.next();
    }

    @Override
    public void remove() {
        iterator.remove();
    }

    @Override
    public Iterator<StorageKey> iterator() {
        return this;
    }

}