storm-server/src/main/java/org/apache/storm/scheduler/IScheduler.java

/**
 * 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.storm.scheduler;

import java.util.Map;

public interface IScheduler {

    void prepare(Map<String, Object> conf);

    /**
     * Set assignments for the topologies which needs scheduling. The new assignments is available 
     * through `cluster.getAssignments()`
     *
     *@param topologies all the topologies in the cluster, some of them need schedule. Topologies object here 
     *       only contain static information about topologies. Information like assignments, slots are all in
     *       the `cluster` object.
     *@param cluster the cluster these topologies are running in. `cluster` contains everything user
     *       need to develop a new scheduling logic. e.g. supervisors information, available slots, current 
     *       assignments for all the topologies etc. User can set the new assignment for topologies using
     *       cluster.setAssignmentById()`
     */
    void schedule(Topologies topologies, Cluster cluster);

    /**
     * This function returns the scheduler's configuration.
     *
     * @return The scheduler's configuration.
     */
    Map config();

    /**
     * called once when the system is shutting down, should be idempotent.
     */
    default void cleanup() {
    }
}