code: /*
   * 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.telemetry.api;
  
  import com.google.common.base.Preconditions;
  import com.google.common.base.Strings;
  import org.apache.skywalking.oap.server.library.module.Service;
  
  /**
   * Open API to telemetry module, allow to create metrics instance with different type. Types inherits from prometheus
   * project, and plan to move to openmetrics APIs after it is ready.
   */
  public interface MetricsCreator extends Service {
  
      String HEALTH_METRIC_PREFIX = "health_check_";
      /**
       * Create a counter type metrics instance.
       */
      CounterMetrics createCounter(String name, String tips, MetricsTag.Keys tagKeys, MetricsTag.Values tagValues);
  
      /**
       * Create a gauge type metrics instance.
       */
      GaugeMetrics createGauge(String name, String tips, MetricsTag.Keys tagKeys, MetricsTag.Values tagValues);
  
      /**
       * Create a Histogram type metrics instance.
       *
       * @param buckets Time bucket for duration.
       */
      HistogramMetrics createHistogramMetric(String name, String tips, MetricsTag.Keys tagKeys,
          MetricsTag.Values tagValues, double... buckets);
  
      /**
       * Create a Health Check gauge.
       */
      default HealthCheckMetrics createHealthCheckerGauge(String name, MetricsTag.Keys tagKeys, MetricsTag.Values tagValues) {
          Preconditions.checkArgument(!Strings.isNullOrEmpty(name), "Require non-null or empty metric name");
          return new HealthCheckMetrics(createGauge(Strings.lenientFormat("%s%s", HEALTH_METRIC_PREFIX, name),
              Strings.lenientFormat("%s health check", name),
              tagKeys, tagValues));
      }
  
      /**
       * Find out whether it's a health check metric.
       */
      default boolean isHealthCheckerMetrics(String name) {
          Preconditions.checkArgument(!Strings.isNullOrEmpty(name), "Require non-null or empty metric name");
          return name.startsWith(HEALTH_METRIC_PREFIX);
      }
  
      /**
       * Extract the raw module name
       */
      default String extractModuleName(String metricName) {
          Preconditions.checkArgument(!Strings.isNullOrEmpty(metricName), "Require non-null or empty metric name");
          return metricName.replace(HEALTH_METRIC_PREFIX, "");
      }
  }
  