org.apache.hadoop.hive.ql.wm.Trigger Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* 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
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*/
package org.apache.hadoop.hive.ql.wm;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
/**
* Trigger interface which gets mapped to CREATE TRIGGER .. queries. A trigger can have a name, expression and action.
* Trigger is a simple expression which gets evaluated during the lifecycle of query and executes an action
* if the expression defined in trigger evaluates to true.
*/
@JsonSerialize
public interface Trigger {
/**
* Based on current value, returns true if trigger is applied else false.
*
* @param current - current value
* @return true if trigger got applied false otherwise
*/
boolean apply(long current);
/**
* Get trigger expression
*
* @return expression
*/
Expression getExpression();
/**
* Return the name of the trigger
*
* @return trigger name
*/
String getName();
/**
* Return the action that will get executed when trigger expression evaluates to true
*
* @return action
*/
Action getAction();
/**
* Return cloned copy of this trigger
*
* @return clone copy
*/
Trigger clone();
/**
* Set trigger violation message. When {@link #apply(long)} returns false, this can be used
* to set message for trigger violation which will be sent as response to clients.
*
* @param violationMsg violation message
*/
void setViolationMsg(String violationMsg);
/**
* Get error message set during trigger violation.
*
* @return trigger violation message
*/
String getViolationMsg();
}