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Java library for cluster communications and computing.

There is a newer version: 4.1.3

/*
 * Copyright 2020 The Hekate Project
 *
 * The Hekate Project 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 io.hekate.cluster.split;

import io.hekate.cluster.ClusterNode;
import io.hekate.cluster.ClusterServiceFactory;

/**
 * Cluster split-brain detector.
 *
 * 
 * This interface represents a component which is responsible for cluster split-brain detection.
 * 
 *
 * 
 * Implementations of this component should perform a quick check (possibly by consulting with some shared resource) and verify that local
 * node can reach other nodes.
 * 
 *
 * 
 * Cluster service calls this component when any of the following events happens:
 * 
 * 
 * Right before the local node joins to the cluster
 * When some other node leaves the cluster
 * Periodically, if {@link ClusterServiceFactory#setSplitBrainCheckInterval(long)} is set to a positive value
 * 
 *
 * 
 * If this component detects that local node can't reach other nodes then the cluster service will take actions according to the {@link
 * SplitBrainAction} defined in its {@link ClusterServiceFactory#setSplitBrainDetector(SplitBrainDetector) configuration}.
 * 
 *
 * 
 * Note that it is possible combine multiple detectors with the help of {@link SplitBrainDetectorGroup}.
 * 
 *
 * @see ClusterServiceFactory#setSplitBrainDetector(SplitBrainDetector)
 */
public interface SplitBrainDetector {
    /**
     * Performs a split-brain check and returns {@code true} if local node can reach other members of the cluster.
     *
     * 
     * If this method returns {@code false} then the cluster service will take actions according to the {@link
     * SplitBrainAction} defined in its {@link ClusterServiceFactory#setSplitBrainDetector(SplitBrainDetector) configuration}.
     * 
     *
     * @param localNode Local node (where the check is performed).
     *
     * @return {@code true} if local node can reach other members of the cluster.
     */
    boolean isValid(ClusterNode localNode);
}