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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.flink.table.runtime.operators.window.assigners;
import org.apache.flink.api.common.ExecutionConfig;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.table.data.RowData;
import org.apache.flink.table.runtime.operators.window.TimeWindow;
import java.time.Duration;
import java.util.Collection;
import java.util.Collections;
import static org.apache.flink.table.runtime.operators.window.TimeWindow.getWindowStartWithOffset;
/**
* A {@link WindowAssigner} that windows elements into fixed-size windows based on the timestamp of
* the elements. Windows cannot overlap.
*/
public class TumblingWindowAssigner extends WindowAssigner
implements InternalTimeWindowAssigner {
private static final long serialVersionUID = -1671849072115929859L;
/** Size of this window. */
private final long size;
/** Offset of this window. Windows start at time N * size + offset, where 0 is the epoch. */
private final long offset;
private final boolean isEventTime;
protected TumblingWindowAssigner(long size, long offset, boolean isEventTime) {
if (size <= 0) {
throw new IllegalArgumentException(
"TumblingWindowAssigner parameters must satisfy size > 0");
}
this.size = size;
this.offset = offset;
this.isEventTime = isEventTime;
}
@Override
public Collection assignWindows(RowData element, long timestamp) {
long start = getWindowStartWithOffset(timestamp, offset, size);
return Collections.singletonList(new TimeWindow(start, start + size));
}
@Override
public TypeSerializer getWindowSerializer(ExecutionConfig executionConfig) {
return new TimeWindow.Serializer();
}
@Override
public boolean isEventTime() {
return isEventTime;
}
@Override
public String toString() {
return "TumblingWindow(" + size + ")";
}
// ------------------------------------------------------------------------
// Utilities
// ------------------------------------------------------------------------
/**
* Creates a new {@code TumblingWindowAssigner} {@link WindowAssigner} that assigns elements to
* time windows based on the element timestamp.
*
* @param size The size of the generated windows.
* @return The time policy.
*/
public static TumblingWindowAssigner of(Duration size) {
return new TumblingWindowAssigner(size.toMillis(), 0, true);
}
/**
* Creates a new {@code TumblingWindowAssigner} {@link WindowAssigner} that assigns elements to
* time windows based on the element timestamp and offset.
*
* For example, if you want window a stream by hour,but window begins at the 15th minutes of
* each hour, you can use {@code of(Time.hours(1),Time.minutes(15))},then you will get time
* windows start at 0:15:00,1:15:00,2:15:00,etc.
*
*
Rather than that,if you are living in somewhere which is not using UTC±00:00 time, such as
* China which is using GMT+08:00,and you want a time window with size of one day, and window
* begins at every 00:00:00 of local time,you may use {@code of(Time.days(1),Time.hours(-8))}.
* The parameter of offset is {@code Time.hours(-8))} since UTC+08:00 is 8 hours earlier than
* UTC time.
*
* @param offset The offset which window start would be shifted by.
* @return The time policy.
*/
public TumblingWindowAssigner withOffset(Duration offset) {
return new TumblingWindowAssigner(size, offset.toMillis(), isEventTime);
}
public TumblingWindowAssigner withEventTime() {
return new TumblingWindowAssigner(size, offset, true);
}
public TumblingWindowAssigner withProcessingTime() {
return new TumblingWindowAssigner(size, offset, false);
}
}