code: /*
   *  LanguageTool, a natural language style checker
   *  * Copyright (C) 2021 Fabian Richter
   *  *
   *  * This library is free software; you can redistribute it and/or
   *  * modify it under the terms of the GNU Lesser General Public
   *  * License as published by the Free Software Foundation; either
   *  * version 2.1 of the License, or (at your option) any later version.
   *  *
   *  * This library is distributed in the hope that it will be useful,
   *  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   *  * Lesser General Public License for more details.
   *  *
   *  * You should have received a copy of the GNU Lesser General Public
   *  * License along with this library; if not, write to the Free Software
   *  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
   *  * USA
   *
   */
  
  package org.languagetool.tools;
  
  import io.github.resilience4j.circuitbreaker.CircuitBreakerRegistry;
  import io.github.resilience4j.micrometer.tagged.TaggedCircuitBreakerMetrics;
  import io.micrometer.core.instrument.Clock;
  import io.micrometer.core.instrument.MeterRegistry;
  import io.micrometer.prometheus.PrometheusConfig;
  import io.micrometer.prometheus.PrometheusMeterRegistry;
  import io.prometheus.client.CollectorRegistry;
  
  /**
   * Keep a central registry of circuit breakers so that we can expose metrics for all of them
   */
  public class CircuitBreakers {
  
    private static final CircuitBreakers instance = new CircuitBreakers();
    private final CircuitBreakerRegistry registry;
  
    private CircuitBreakers() {
      registry = CircuitBreakerRegistry.ofDefaults();
      MeterRegistry metricsRegistry = new PrometheusMeterRegistry(PrometheusConfig.DEFAULT,
        CollectorRegistry.defaultRegistry, Clock.SYSTEM);
      TaggedCircuitBreakerMetrics.ofCircuitBreakerRegistry(registry).bindTo(metricsRegistry);
    }
  
    public static CircuitBreakerRegistry registry() {
      return instance.registry;
    }
  }
  