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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.

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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.cassandra.db.guardrails;

import java.util.function.ToLongFunction;
import javax.annotation.Nullable;

import org.apache.cassandra.service.ClientState;

/**
 * {@link MinThreshold} for minimum guardrails, the value is checked to see if it is lesser than the warn and fail thresholds.
 */
public class MinThreshold extends Threshold
{
    /**
     * Creates a new minimum threshold guardrail.
     *
     * @param name            the identifying name of the guardrail
     * @param reason          the optional description of the reason for guarding the operation
     * @param warnThreshold   a {@link ClientState}-based provider of the value above which a warning should be triggered.
     * @param failThreshold   a {@link ClientState}-based provider of the value above which the operation should be aborted.
     * @param messageProvider a function to generate the warning or error message if the guardrail is triggered
     */
    public MinThreshold(String name,
                        @Nullable String reason,
                        ToLongFunction warnThreshold,
                        ToLongFunction failThreshold,
                        Threshold.ErrorMessageProvider messageProvider)
    {
        super(name, reason, warnThreshold, failThreshold, messageProvider);
    }

    @Override
    protected boolean compare(long value, long threshold)
    {
        return value < threshold;
    }

    @Override
    protected long failValue(ClientState state)
    {
        long failValue = failThreshold.applyAsLong(state);
        return failValue <= 0 ? Long.MIN_VALUE : failValue;
    }

    @Override
    protected long warnValue(ClientState state)
    {
        long warnValue = warnThreshold.applyAsLong(state);
        return warnValue <= 0 ? Long.MIN_VALUE : warnValue;
    }

}