org.apache.kafka.streams.kstream.Windows Maven / Gradle / Ivy
/*
* 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 interface for fixed size windows that is used to define window boundaries and window
* maintain duration.
*
* If not explicitly specified, the default maintain duration is 1 day.
* For time semantics, see {@link TimestampExtractor}.
*
* @param type of the window instance
* @see TimeWindows
* @see UnlimitedWindows
* @see JoinWindows
* @see SessionWindows
* @see TimestampExtractor
*/
public abstract class Windows {
private static final int DEFAULT_NUM_SEGMENTS = 3;
static final long DEFAULT_MAINTAIN_DURATION_MS = 24 * 60 * 60 * 1000L; // one day
private long maintainDurationMs;
public int segments;
protected Windows() {
segments = DEFAULT_NUM_SEGMENTS;
maintainDurationMs = DEFAULT_MAINTAIN_DURATION_MS;
}
/**
* Set the window maintain duration (retention time) in milliseconds.
* This retention time is a guaranteed lower bound for how long a window will be maintained.
*
* @param durationMs the window retention time in milliseconds
* @return itself
* @throws IllegalArgumentException if {@code durationMs} is negative
*/
// This should always get overridden to provide the correct return type and thus to avoid a cast
public Windows until(final long durationMs) throws IllegalArgumentException {
if (durationMs < 0) {
throw new IllegalArgumentException("Window retention time (durationMs) cannot be negative.");
}
maintainDurationMs = durationMs;
return this;
}
/**
* Return the window maintain duration (retention time) in milliseconds.
*
* @return the window maintain duration
*/
public long maintainMs() {
return maintainDurationMs;
}
/**
* Set the number of segments to be used for rolling the window store.
* This function is not exposed to users but can be called by developers that extend this class.
*
* @param segments the number of segments to be used
* @return itself
* @throws IllegalArgumentException if specified segments is small than 2
*/
protected Windows segments(final int segments) throws IllegalArgumentException {
if (segments < 2) {
throw new IllegalArgumentException("Number of segments must be at least 2.");
}
this.segments = segments;
return this;
}
/**
* 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();
}