org.apache.kafka.streams.kstream.Windows Maven / Gradle / Ivy
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* 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,
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* 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.
*
* 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 late and will not be processed but are dropped.
*
* 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 type of the window instance
* @see TimeWindows
* @see UnlimitedWindows
* @see JoinWindows
* @see SessionWindows
* @see TimestampExtractor
*/
public abstract class Windows {
/**
* 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 KIP-633 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 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();
}