content: /*
   * Copyright 1999-2019 Alibaba Group Holding Ltd.
   *
   * Licensed 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
   *
   *      https://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 com.alibaba.csp.sentinel.heartbeat;
  
  import com.alibaba.csp.sentinel.log.RecordLog;
  import com.alibaba.csp.sentinel.transport.HeartbeatSender;
  import com.alibaba.csp.sentinel.spi.SpiLoader;
  
  /**
   * @author Eric Zhao
   * @since 1.6.0
   */
  public final class HeartbeatSenderProvider {
  
      private static HeartbeatSender heartbeatSender = null;
  
      static {
          resolveInstance();
      }
  
      private static void resolveInstance() {
          HeartbeatSender resolved = SpiLoader.of(HeartbeatSender.class).loadHighestPriorityInstance();
          if (resolved == null) {
              RecordLog.warn("[HeartbeatSenderProvider] WARN: No existing HeartbeatSender found");
          } else {
              heartbeatSender = resolved;
              RecordLog.info("[HeartbeatSenderProvider] HeartbeatSender activated: {}", resolved.getClass()
                  .getCanonicalName());
          }
      }
  
      /**
       * Get resolved {@link HeartbeatSender} instance.
       *
       * @return resolved {@code HeartbeatSender} instance
       */
      public static HeartbeatSender getHeartbeatSender() {
          return heartbeatSender;
      }
  
      private HeartbeatSenderProvider() {}
  }
  