/*
* 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.beam.sdk.transforms.windowing;
import java.util.List;
import java.util.Objects;
import org.apache.beam.sdk.annotations.Experimental;
import org.apache.beam.sdk.transforms.windowing.Trigger.OnceTrigger;
import org.joda.time.Instant;
/**
* A {@link Trigger} that fires at some point after a specified number of input elements have
* arrived.
*/
@Experimental(Experimental.Kind.TRIGGER)
public class AfterPane extends OnceTrigger {
private final int countElems;
private AfterPane(int countElems) {
super(null);
this.countElems = countElems;
}
/**
* The number of elements after which this trigger may fire.
*/
public int getElementCount() {
return countElems;
}
/**
* Creates a trigger that fires when the pane contains at least {@code countElems} elements.
*/
public static AfterPane elementCountAtLeast(int countElems) {
return new AfterPane(countElems);
}
@Override
public boolean isCompatible(Trigger other) {
return this.equals(other);
}
@Override
public Instant getWatermarkThatGuaranteesFiring(BoundedWindow window) {
return BoundedWindow.TIMESTAMP_MAX_VALUE;
}
@Override
protected OnceTrigger getContinuationTrigger(List<Trigger> continuationTriggers) {
return AfterPane.elementCountAtLeast(1);
}
@Override
public String toString() {
return "AfterPane.elementCountAtLeast(" + countElems + ")";
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (!(obj instanceof AfterPane)) {
return false;
}
AfterPane that = (AfterPane) obj;
return this.countElems == that.countElems;
}
@Override
public int hashCode() {
return Objects.hash(countElems);
}
}