crunch-lambda/src/main/java/org/apache/crunch/lambda/LDoFnWrapper.java

/**
 * 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.lambda;

import org.apache.crunch.DoFn;
import org.apache.crunch.Emitter;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.TaskInputOutputContext;

class LDoFnWrapper<S, T> extends DoFn<S, T> {

    private final LDoFn<S, T> fn;
    private transient Context<S, T> ctxt;

    public LDoFnWrapper(LDoFn<S, T> fn) {
        this.fn = fn;
    }

    @Override
    public void initialize() {
        super.initialize();
        if (getContext() == null) {
            this.ctxt = new Context<>(getConfiguration());
        } else {
            this.ctxt = new Context<>(getContext());
        }
    }

    @Override
    public void process(S input, Emitter<T> emitter) {
        fn.process(ctxt.update(input, emitter));
    }
    static class Context<S, T> implements LDoFnContext<S, T> {
        private S element;
        private Emitter<T> emitter;
        private TaskInputOutputContext context;
        private Configuration conf;

        public Context(TaskInputOutputContext context) {
            this.context = context;
            this.conf = context.getConfiguration();
        }

        public Context(Configuration conf) {
            this.context = null;
            this.conf = conf;
        }

        public Context<S, T> update(S element, Emitter<T> emitter) {
            this.element = element;
            this.emitter = emitter;
            return this;
        }

        public S element() {
            return element;
        }

        public void emit(T t) {
            emitter.emit(t);
        }

        public TaskInputOutputContext getContext() {
            return context;
        }

        public Configuration getConfiguration() {
            return conf;
        }

        public void increment(String groupName, String counterName) {
            increment(groupName, counterName, 1);
        }

        public void increment(String groupName, String counterName, long value) {
            if (context != null) {
                context.getCounter(groupName, counterName).increment(value);
            }
        }

        public void increment(Enum<?> counterName) {
            increment(counterName, 1);
        }

        public void increment(Enum<?> counterName, long value) {
            if (context != null) {
                context.getCounter(counterName).increment(value);
            }
        }
    }
}