/*
 * 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.kafka.common.replica;

import org.apache.kafka.common.Configurable;
import org.apache.kafka.common.TopicPartition;

import java.io.Closeable;
import java.io.IOException;
import java.util.Map;
import java.util.Optional;

/**
 * Plug-able interface for selecting a preferred read replica given the current set of replicas for a partition
 * and metadata from the client.
 * Implement {@link org.apache.kafka.common.metrics.Monitorable} to enable the selector to register metrics.
 * The following tags are automatically added to all metrics registered: <code>config</code> set to
 * <code>replica.selector.class</code>, and <code>class</code> set to the ReplicaSelector class name.
 */
public interface ReplicaSelector extends Configurable, Closeable {

    /**
     * Select the preferred replica a client should use for fetching. If no replica is available, this will return an
     * empty optional.
     */
    Optional<ReplicaView> select(TopicPartition topicPartition,
                                 ClientMetadata clientMetadata,
                                 PartitionView partitionView);
    @Override
    default void close() throws IOException {
        // No-op by default
    }

    @Override
    default void configure(Map<String, ?> configs) {
        // No-op by default
    }
}
