kafka Windows 源码

kafka Windows 代码

文件路径：/streams/src/main/java/org/apache/kafka/streams/kstream/Windows.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.kafka.streams.kstream;

import org.apache.kafka.streams.processor.TimestampExtractor;

import java.util.Map;

/**
 * The window specification for fixed size windows that is used to define window boundaries and grace period.
 * <p>
 * Grace period defines how long to wait on out-of-order events. That is, windows will continue to accept new records until {@code stream_time >= window_end + grace_period}.
 * Records that arrive after the grace period passed are considered <em>late</em> and will not be processed but are dropped.
 * <p>
 * Warning: It may be unsafe to use objects of this class in set- or map-like collections,
 * since the equals and hashCode methods depend on mutable fields.
 *
 * @param <W> type of the window instance
 * @see TimeWindows
 * @see UnlimitedWindows
 * @see JoinWindows
 * @see SessionWindows
 * @see TimestampExtractor
 */
public abstract class Windows<W extends Window> {

    /**
     * By default grace period is 24 hours for all windows in other words we allow out-of-order data for up to a day
     * This behavior is now deprecated and additional details are available in the motivation for the KIP
     * Check out <a href="https://cwiki.apache.org/confluence/x/Ho2NCg">KIP-633</a> for more details
     */
    protected static final long DEPRECATED_DEFAULT_24_HR_GRACE_PERIOD = 24 * 60 * 60 * 1000L;

    /**
     * This constant is used as the specified grace period where we do not have any grace periods instead of magic constants
     */
    protected static final long NO_GRACE_PERIOD = 0L;

    protected Windows() {}

    /**
     * Create all windows that contain the provided timestamp, indexed by non-negative window start timestamps.
     *
     * @param timestamp the timestamp window should get created for
     * @return a map of {@code windowStartTimestamp -> Window} entries
     */
    public abstract Map<Long, W> windowsFor(final long timestamp);

    /**
     * Return the size of the specified windows in milliseconds.
     *
     * @return the size of the specified windows
     */
    public abstract long size();

    /**
     * Return the window grace period (the time to admit
     * out-of-order events after the end of the window.)
     *
     * Delay is defined as (stream_time - record_timestamp).
     */
    public abstract long gracePeriodMs();
}

相关信息

kafka 源码目录

相关文章

kafka Aggregator 源码

kafka Branched 源码

kafka BranchedKStream 源码

kafka CogroupedKStream 源码

kafka Consumed 源码

kafka EmitStrategy 源码

kafka ForeachAction 源码

kafka ForeachProcessor 源码

kafka GlobalKTable 源码

kafka Grouped 源码