/*
 * 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.pulsar.functions.instance.stats;

import io.prometheus.client.Collector;
import java.util.HashMap;
import java.util.Map;

public class FunctionCollectorRegistryImpl extends FunctionCollectorRegistry {

    private final Map<String, Collector> namesToCollectors = new HashMap<String, Collector>();

    public Collector registerIfNotExist(String metricName, Collector collector) {
        synchronized (this) {
            Collector existingCollector = namesToCollectors.get(metricName);
            if (existingCollector == null) {
                namesToCollectors.put(metricName, collector);
                super.register(collector);
                return collector;
            }
            return existingCollector;
        }
    }
}
