content: /*
   * Copyright 1999-2018 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
   *
   *      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 com.alibaba.csp.sentinel.cluster.flow.statistic.limit;
  
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  
  import com.alibaba.csp.sentinel.cluster.server.config.ClusterServerConfigManager;
  import com.alibaba.csp.sentinel.util.AssertUtil;
  
  /**
   * @author Eric Zhao
   * @since 1.4.1
   */
  public final class GlobalRequestLimiter {
  
      private static final Map<String, RequestLimiter> GLOBAL_QPS_LIMITER_MAP = new ConcurrentHashMap<>();
  
      public static void initIfAbsent(String namespace) {
          AssertUtil.notEmpty(namespace, "namespace cannot be empty");
          if (!GLOBAL_QPS_LIMITER_MAP.containsKey(namespace)) {
              GLOBAL_QPS_LIMITER_MAP.put(namespace, new RequestLimiter(ClusterServerConfigManager.getMaxAllowedQps(namespace)));
          }
      }
  
      public static RequestLimiter getRequestLimiter(String namespace) {
          if (namespace == null) {
              return null;
          }
          return GLOBAL_QPS_LIMITER_MAP.get(namespace);
      }
  
      public static boolean tryPass(String namespace) {
          if (namespace == null) {
              return false;
          }
          RequestLimiter limiter = GLOBAL_QPS_LIMITER_MAP.get(namespace);
          if (limiter == null) {
              return true;
          }
          return limiter.tryPass();
      }
  
      public static double getCurrentQps(String namespace) {
          RequestLimiter limiter = getRequestLimiter(namespace);
          if (limiter == null) {
              return 0;
          }
          return limiter.getQps();
      }
  
      public static double getMaxAllowedQps(String namespace) {
          RequestLimiter limiter = getRequestLimiter(namespace);
          if (limiter == null) {
              return 0;
          }
          return limiter.getQpsAllowed();
      }
  
      public static void applyMaxQpsChange(double maxAllowedQps) {
          AssertUtil.isTrue(maxAllowedQps >= 0, "max allowed QPS should > 0");
          for (RequestLimiter limiter : GLOBAL_QPS_LIMITER_MAP.values()) {
              if (limiter != null) {
                  limiter.setQpsAllowed(maxAllowedQps);
              }
          }
      }
  
      private GlobalRequestLimiter() {}
  }
  