org.apache.beam.sdk.util.IdentitySideInputWindowFn.java Source code

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Here is the source code for org.apache.beam.sdk.util.IdentitySideInputWindowFn.java

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/*
 * 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.beam.sdk.util;

import java.util.Collection;
import java.util.Collections;
import org.apache.beam.sdk.coders.Coder;
import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
import org.apache.beam.sdk.transforms.windowing.GlobalWindow;
import org.apache.beam.sdk.transforms.windowing.NonMergingWindowFn;
import org.apache.beam.sdk.transforms.windowing.WindowFn;
import org.apache.beam.sdk.transforms.windowing.WindowMappingFn;
import org.joda.time.Duration;

/**
 * A {@link WindowFn} for use during tests that returns the input window for calls to
 * {@link #getSideInputWindow(BoundedWindow)}.
 */
public class IdentitySideInputWindowFn extends NonMergingWindowFn<Integer, BoundedWindow> {
    @Override
    public Collection<BoundedWindow> assignWindows(WindowFn<Integer, BoundedWindow>.AssignContext c)
            throws Exception {
        return Collections.singleton(c.window());
    }

    @Override
    public boolean isCompatible(WindowFn<?, ?> other) {
        return true;
    }

    @Override
    public Coder<BoundedWindow> windowCoder() {
        // not used
        return (Coder) GlobalWindow.Coder.INSTANCE;
    }

    @Override
    public WindowMappingFn<BoundedWindow> getDefaultWindowMappingFn() {
        return new WindowMappingFn<BoundedWindow>() {
            @Override
            public BoundedWindow getSideInputWindow(BoundedWindow window) {
                return window;
            }

            @Override
            public Duration maximumLookback() {
                return Duration.ZERO;
            }
        };
    }
}