oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/ComponentLibraryCatalogUtil.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.skywalking.oap.server.core;

import org.apache.skywalking.oap.server.core.config.ComponentLibraryCatalogService;

/**
 * ComponentLibraryCatalogUtil provides convenience access for {@link ComponentLibraryCatalogService} service in the
 * core module's default provider.
 * Notice, this util should not be used out of the core module's default provide, otherwise, it breaks the isolation
 * cross modules.
 *
 * @since 9.4.0
 */
public class ComponentLibraryCatalogUtil {
    private static ComponentLibraryCatalogService REF;

    public static ComponentLibraryCatalogService hold(final ComponentLibraryCatalogService ref) {
        if (REF != null) {
            throw new IllegalStateException("REF had been initialized. Repeatedly initialization is not allowed");
        }
        ComponentLibraryCatalogUtil.REF = ref;
        return ComponentLibraryCatalogUtil.REF;
    }

    public static ComponentLibraryCatalogService get() {
        if (REF == null) {
            throw new IllegalStateException("REF is not initialized");
        }
        return REF;
    }
}