org.apache.flink.streaming.api.windowing.evictors.TimeEvictor.java Source code

Introduction

Here is the source code for org.apache.flink.streaming.api.windowing.evictors.TimeEvictor.java

Source

/**
 * 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.flink.streaming.api.windowing.evictors;

import com.google.common.collect.Iterables;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.annotation.VisibleForTesting;
import org.apache.flink.streaming.api.windowing.time.Time;
import org.apache.flink.streaming.api.windowing.windows.Window;
import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;

/**
 * An {@link Evictor} that keeps elements for a certain amount of time. Elements older
 * than {@code current_time - keep_time} are evicted.
 *
 * @param <W> The type of {@link Window Windows} on which this {@code Evictor} can operate.
 */
@PublicEvolving
public class TimeEvictor<W extends Window> implements Evictor<Object, W> {
    private static final long serialVersionUID = 1L;

    private final long windowSize;

    public TimeEvictor(long windowSize) {
        this.windowSize = windowSize;
    }

    @Override
    public int evict(Iterable<StreamRecord<Object>> elements, int size, W window) {
        int toEvict = 0;
        long currentTime = Iterables.getLast(elements).getTimestamp();
        long evictCutoff = currentTime - windowSize;
        for (StreamRecord<Object> record : elements) {
            if (record.getTimestamp() > evictCutoff) {
                break;
            }
            toEvict++;
        }
        return toEvict;
    }

    @Override
    public String toString() {
        return "TimeEvictor(" + windowSize + ")";
    }

    @VisibleForTesting
    public long getWindowSize() {
        return windowSize;
    }

    /**
     * Creates a {@code TimeEvictor} that keeps the given number of elements.
     *
     * @param windowSize The amount of time for which to keep elements.
     */
    public static <W extends Window> TimeEvictor<W> of(Time windowSize) {
        return new TimeEvictor<>(windowSize.toMilliseconds());
    }
}