org.apache.hadoop.hive.ql.wm.Expression Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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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
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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;
/**
* Expression that is defined in triggers.
* Most expressions will get triggered only after exceeding a limit. As a result, only greater than (>) expression
* is supported.
*/
public interface Expression {
enum Predicate {
GREATER_THAN(">");
String symbol;
Predicate(final String symbol) {
this.symbol = symbol;
}
public String getSymbol() {
return symbol;
}
}
interface Builder {
Builder greaterThan(CounterLimit counter);
Expression build();
}
/**
* Evaluate current value against this expression. Return true if expression evaluates to true (current > limit)
* else false otherwise
*
* @param current - current value against which expression will be evaluated
* @return true if current value exceeds limit
*/
boolean evaluate(final long current);
/**
* Return counter limit
*
* @return counter limit
*/
CounterLimit getCounterLimit();
/**
* Return predicate defined in the expression.
*
* @return predicate
*/
Predicate getPredicate();
/**
* Return cloned copy of this expression.
*
* @return cloned copy
*/
Expression clone();
}