com.google.cloud.dataflow.sdk.util.ListOutputBuffer.java Source code

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Here is the source code for com.google.cloud.dataflow.sdk.util.ListOutputBuffer.java

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/*
 * Copyright (C) 2015 Google 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 com.google.cloud.dataflow.sdk.util;

import com.google.cloud.dataflow.sdk.coders.Coder;
import com.google.cloud.dataflow.sdk.transforms.windowing.BoundedWindow;
import com.google.cloud.dataflow.sdk.values.CodedTupleTag;
import com.google.common.collect.Iterables;

import java.io.IOException;

/**
 * {code OutputBuffer} that buffers input values emitting all added values as an Iterable.
 */
class ListOutputBuffer<K, T, W extends BoundedWindow> implements OutputBuffer<K, T, Iterable<T>, W> {

    private static final long serialVersionUID = 0L;

    private CodedTupleTag<T> bufferTag;

    public ListOutputBuffer(Coder<T> itemCoder) {
        bufferTag = CodedTupleTag.of(BUFFER_NAME, itemCoder);
    }

    @Override
    public void addValue(Context<K, W> c, T input) throws IOException {
        c.addToBuffer(c.window(), bufferTag, input);
    }

    @Override
    public Iterable<T> extract(Context<K, W> c) throws IOException {
        Iterable<T> result = c.readBuffers(bufferTag, c.sourceWindows());
        return Iterables.isEmpty(result) ? null : result;
    }

    @Override
    public void clear(Context<K, W> c) throws IOException {
        c.clearBuffers(bufferTag, c.sourceWindows());
    }

    @Override
    public void flush(Context<K, W> c) throws IOException {
    }
}