/*
* 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 com.alibaba.jstorm.window;
public class EventTimeTrigger<T> extends Trigger<T> {
private static final long serialVersionUID = 1L;
private EventTimeTrigger() {
}
/**
* If a watermark arrives, we need to check all pending windows.
* If any of the pending window suffices, we should fire immediately by registering a timer without delay.
* Otherwise we register a timer whose time is the window end plus max lag time
*/
@Override
public TriggerResult onElement(Object element, long timestamp, TimeWindow window, TriggerContext ctx) {
ctx.registerEventTimeTimer(window.getEnd() + ctx.getMaxLagMs(), window);
return TriggerResult.CONTINUE;
}
@Override
public String toString() {
return "EventTimeTrigger()";
}
/**
* Creates an event-time trigger that fires once the watermark passes the end of the window.
*
* <p>
* Once the trigger fires all elements are discarded. Elements that arrive late immediately
* trigger window evaluation with just this one element.
*/
public static <T> EventTimeTrigger<T> create() {
return new EventTimeTrigger<>();
}
}