modules/core/src/main/java/org/apache/ignite/cluster/ClusterState.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.ignite.cluster;

import org.jetbrains.annotations.Nullable;

/**
 * Cluster states.
 */
public enum ClusterState {
    /**
     * Cluster deactivated. Cache operations aren't allowed.
     * <p>
     * <b>NOTE:</b>
     * Deactivation clears in-memory caches (without persistence) including the system caches.
     */
    INACTIVE,

    /** Cluster activated. All cache operations are allowed. */
    ACTIVE,

    /** Cluster activated. Cache read operation allowed, Cache data change operation aren't allowed. */
    ACTIVE_READ_ONLY;

    /** Enumerated values. */
    private static final ClusterState[] VALS = values();

    /**
     * Efficiently gets enumerated value from its ordinal.
     *
     * @param ord Ordinal value.
     * @return Enumerated value or {@code null} if ordinal out of range.
     */
    @Nullable public static ClusterState fromOrdinal(int ord) {
        return ord >= 0 && ord < VALS.length ? VALS[ord] : null;
    }

    /**
     * @param state Cluster state
     * @return {@code True} if cluster in given cluster {@code state} is activated and {@code False} otherwise.
     */
    public static boolean active(ClusterState state) {
        return state != INACTIVE;
    }

    /**
     * @param state1 First given state.
     * @param state2 Second given state.
     * @return Lesser of given states. The order: {@link #ACTIVE} > {@link #ACTIVE_READ_ONLY} > {@link #INACTIVE}.
     */
    public static ClusterState lesserOf(ClusterState state1, ClusterState state2) {
        if (state1 == state2)
            return state1;

        if (state1 == INACTIVE || state2 == INACTIVE)
            return INACTIVE;

        if (state1 == ACTIVE_READ_ONLY || state2 == ACTIVE_READ_ONLY)
            return ACTIVE_READ_ONLY;

        throw new IllegalArgumentException("Unknown cluster states. state1: " + state1 + ", state2: " + state2);
    }
}