co.cask.cdap.etl.mock.batch.MockExternalSink.java Source code

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Here is the source code for co.cask.cdap.etl.mock.batch.MockExternalSink.java

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/*
 * Copyright  2016 Cask Data, Inc.
 *
 * 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 co.cask.cdap.etl.mock.batch;

import co.cask.cdap.api.annotation.Name;
import co.cask.cdap.api.annotation.Plugin;
import co.cask.cdap.api.data.batch.Output;
import co.cask.cdap.api.data.batch.OutputFormatProvider;
import co.cask.cdap.api.data.format.StructuredRecord;
import co.cask.cdap.api.dataset.lib.KeyValue;
import co.cask.cdap.api.plugin.PluginClass;
import co.cask.cdap.api.plugin.PluginConfig;
import co.cask.cdap.api.plugin.PluginPropertyField;
import co.cask.cdap.etl.api.Emitter;
import co.cask.cdap.etl.api.batch.BatchSink;
import co.cask.cdap.etl.api.batch.BatchSinkContext;
import co.cask.cdap.etl.proto.v2.ETLPlugin;
import com.google.common.base.Charsets;
import com.google.common.base.Function;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Lists;
import com.google.common.io.Files;
import com.google.gson.Gson;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;

import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.annotation.Nullable;

/**
 * Mock sink that writes records to a Table and has a utility method for getting all records written.
 */
@Plugin(type = BatchSink.PLUGIN_TYPE)
@Name(MockExternalSink.PLUGIN_NAME)
public class MockExternalSink extends BatchSink<StructuredRecord, NullWritable, String> {
    public static final PluginClass PLUGIN_CLASS = getPluginClass();
    public static final String PLUGIN_NAME = "MockExternalSink";
    private static final Gson GSON = new Gson();
    private final Config config;

    public MockExternalSink(Config config) {
        this.config = config;
    }

    /**
     * Config for the sink.
     */
    public static class Config extends PluginConfig {
        @Nullable
        private String name;
        private String alias;
        private String dirName;
    }

    @Override
    public void prepareRun(BatchSinkContext context) throws Exception {
        OutputFormatProvider outputFormatProvider = new OutputFormatProvider() {
            @Override
            public String getOutputFormatClassName() {
                return TextOutputFormat.class.getCanonicalName();
            }

            @Override
            public Map<String, String> getOutputFormatConfiguration() {
                return ImmutableMap.of(TextOutputFormat.OUTDIR, config.dirName);
            }
        };

        if (config.name != null) {
            Output output = Output.of(config.name, outputFormatProvider);
            output.alias(config.alias);
            context.addOutput(output);
        } else {
            context.addOutput(config.alias, outputFormatProvider);
        }
    }

    @Override
    public void transform(StructuredRecord input, Emitter<KeyValue<NullWritable, String>> emitter)
            throws Exception {
        emitter.emit(new KeyValue<>(NullWritable.get(), GSON.toJson(input)));
    }

    /**
     * Returns {@link ETLPlugin} for MockExternalSink.
     *
     * @param name name of the provider, use null for backwards compatibility
     * @param alias alias of the provider
     * @param dirName directory name
     * @return {@link ETLPlugin} for MockExternalSink
     */
    public static ETLPlugin getPlugin(@Nullable String name, String alias, String dirName) {
        Map<String, String> properties = new HashMap<>();
        if (name != null) {
            properties.put("name", name);
        }
        properties.put("alias", alias);
        properties.put("dirName", dirName);
        return new ETLPlugin(PLUGIN_NAME, BatchSink.PLUGIN_TYPE, properties, null);
    }

    /**
     * Used to read the records written by this sink.
     *
     * @param dirName directory where output files are found
     */
    public static List<StructuredRecord> readOutput(String dirName) throws Exception {
        File dir = new File(dirName);
        File[] files = dir.listFiles(new FilenameFilter() {
            @Override
            public boolean accept(File dir, String name) {
                return name.startsWith("part");
            }
        });
        if (files == null) {
            return Collections.emptyList();
        }

        List<StructuredRecord> records = new ArrayList<>();
        for (File file : files) {
            records.addAll(Lists.transform(Files.readLines(file, Charsets.UTF_8),
                    new Function<String, StructuredRecord>() {
                        @Override
                        public StructuredRecord apply(String input) {
                            return GSON.fromJson(input, StructuredRecord.class);
                        }
                    }));
        }
        return records;
    }

    private static PluginClass getPluginClass() {
        Map<String, PluginPropertyField> properties = new HashMap<>();
        properties.put("name", new PluginPropertyField("name", "", "string", false));
        properties.put("alias", new PluginPropertyField("alias", "", "string", true));
        properties.put("dirName", new PluginPropertyField("dirName", "", "string", true));
        return new PluginClass(BatchSink.PLUGIN_TYPE, PLUGIN_NAME, "", MockExternalSink.class.getName(), "config",
                properties);
    }
}