Java tutorial
/** * 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.lib; import com.google.common.collect.ImmutableList; import com.google.common.collect.ImmutableMultiset; import org.apache.commons.io.FileUtils; import org.apache.crunch.PCollection; import org.apache.crunch.Pipeline; import org.apache.crunch.impl.mr.MRPipeline; import org.apache.crunch.io.From; import org.apache.crunch.test.TemporaryPath; import org.junit.Rule; import org.junit.Test; import java.io.File; import static org.junit.Assert.assertEquals; public class ShardIT { @Rule public TemporaryPath tempDir = new TemporaryPath("crunch.tmp.dir", "hadoop.tmp.dir"); @Test public void testShard() throws Exception { File inDir = tempDir.getFile("in"); FileUtils.writeLines(new File(inDir, "part1"), ImmutableList.of("part1", "part1")); FileUtils.writeLines(new File(inDir, "part2"), ImmutableList.of("part2")); Pipeline pipeline = new MRPipeline(ShardIT.class); PCollection<String> in = pipeline.read(From.textFile(inDir.getPath())); // We can only test on 1 shard here, as local MR does not support multiple reducers. PCollection<String> out = Shard.shard(in, 1); assertEquals(ImmutableMultiset.copyOf(out.materialize()), ImmutableMultiset.of("part1", "part1", "part2")); } }