BrokerFilter.java

/**
 * Copyright 2016 Yahoo Inc.
 *
 * Licensed 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.yahoo.pulsar.broker.loadbalance;

import java.util.Set;

import com.yahoo.pulsar.broker.BundleData;
import com.yahoo.pulsar.broker.PulsarService;
import com.yahoo.pulsar.broker.ServiceConfiguration;

/**
 * Load management component which determines what brokers should not be considered for topic placement by the placement
 * strategy. For example, the placement strategy may determine that the broker with the least msg/s should get the
 * bundle assignment, but we may not want to consider brokers whose CPU usage is very high. Thus, we could use a filter
 * to blacklist brokers with high CPU usage.
 */
public interface BrokerFilter {

    /**
     * From the given set of available broker candidates, filter those using the load data.
     * 
     * @param brokers
     *            The currently available brokers that have not already been filtered. This set may be modified by
     *            filter.
     * @param bundleToAssign
     *            The data for the bundle to assign.
     * @param loadData
     *            The load data from the leader broker.
     * @param conf
     *            The service configuration.
     * @throws BrokerFilterException
     *            There was an error in the pipeline and the brokers should be reset to their original value
     */
    public void filter(Set<String> brokers, BundleData bundleToAssign, LoadData loadData, ServiceConfiguration conf)
                       throws BrokerFilterException;
}