content: /*
   * 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.camel.component.metrics;
  
  import com.codahale.metrics.Gauge;
  import com.codahale.metrics.MetricRegistry;
  import org.apache.camel.Exchange;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static org.apache.camel.component.metrics.MetricsConstants.HEADER_GAUGE_SUBJECT;
  
  public class GaugeProducer extends AbstractMetricsProducer {
  
      private static final Logger LOG = LoggerFactory.getLogger(GaugeProducer.class);
  
      public GaugeProducer(MetricsEndpoint endpoint) {
          super(endpoint);
          Gauge<?> gauge = endpoint.getRegistry().getGauges().get(endpoint.getMetricsName());
          if (gauge instanceof CamelMetricsGauge) {
              CamelMetricsGauge camelMetricsGauge = (CamelMetricsGauge) gauge;
              if (endpoint.getSubject() != null) {
                  camelMetricsGauge.setValue(endpoint.getSubject());
              }
          } else {
              if (endpoint.getSubject() != null) {
                  endpoint.getRegistry().register(endpoint.getMetricsName(), new CamelMetricsGauge(endpoint.getSubject()));
              } else {
                  LOG.info("No subject found for Gauge \"{}\". Ignoring...", endpoint.getMetricsName());
              }
          }
      }
  
      @Override
      protected void doProcess(Exchange exchange, MetricsEndpoint endpoint, MetricRegistry registry, String metricsName)
              throws Exception {
          Gauge<?> gauge = registry.getGauges().get(metricsName);
          if (gauge instanceof CamelMetricsGauge) {
              CamelMetricsGauge camelMetricsGauge = (CamelMetricsGauge) gauge;
              Object subject = exchange.getIn().getHeader(HEADER_GAUGE_SUBJECT, Object.class);
              if (subject != null) {
                  camelMetricsGauge.setValue(subject);
              }
          } else {
              Object subject = exchange.getIn().getHeader(HEADER_GAUGE_SUBJECT, Object.class);
              Object finalSubject = subject != null ? subject : endpoint.getSubject();
              if (finalSubject != null) {
                  registry.register(metricsName, new CamelMetricsGauge(finalSubject));
              } else {
                  LOG.info("No subject found for Gauge \"{}\". Ignoring...", metricsName);
              }
          }
      }
  
      static class CamelMetricsGauge implements Gauge<Object> {
          private Object subject;
  
          CamelMetricsGauge(Object subject) {
              this.subject = subject;
          }
  
          @Override
          public Object getValue() {
              return subject;
          }
  
          public void setValue(Object subject) {
              this.subject = subject;
          }
      }
  }
  