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.server.envoy.rls.flow;
  
  import com.alibaba.csp.sentinel.cluster.TokenResult;
  import com.alibaba.csp.sentinel.cluster.TokenResultStatus;
  import com.alibaba.csp.sentinel.cluster.flow.statistic.ClusterMetricStatistics;
  import com.alibaba.csp.sentinel.cluster.flow.statistic.data.ClusterFlowEvent;
  import com.alibaba.csp.sentinel.cluster.flow.statistic.metric.ClusterMetric;
  import com.alibaba.csp.sentinel.cluster.server.config.ClusterServerConfigManager;
  import com.alibaba.csp.sentinel.cluster.server.log.ClusterServerStatLogUtil;
  import com.alibaba.csp.sentinel.slots.block.flow.FlowRule;
  
  /**
   * @author Eric Zhao
   * @since 1.7.0
   */
  public final class SimpleClusterFlowChecker {
  
      public static TokenResult acquireClusterToken(/*@Valid*/ FlowRule rule, int acquireCount) {
          Long id = rule.getClusterConfig().getFlowId();
  
          ClusterMetric metric = ClusterMetricStatistics.getMetric(id);
          if (metric == null) {
              return new TokenResult(TokenResultStatus.FAIL);
          }
  
          double latestQps = metric.getAvg(ClusterFlowEvent.PASS);
          double globalThreshold = rule.getCount() * ClusterServerConfigManager.getExceedCount();
          double nextRemaining = globalThreshold - latestQps - acquireCount;
  
          if (nextRemaining >= 0) {
              metric.add(ClusterFlowEvent.PASS, acquireCount);
              metric.add(ClusterFlowEvent.PASS_REQUEST, 1);
  
              ClusterServerStatLogUtil.log("flow|pass|" + id, acquireCount);
              ClusterServerStatLogUtil.log("flow|pass_request|" + id, 1);
  
              // Remaining count is cut down to a smaller integer.
              return new TokenResult(TokenResultStatus.OK)
                  .setRemaining((int) nextRemaining)
                  .setWaitInMs(0);
          } else {
              // Blocked.
              metric.add(ClusterFlowEvent.BLOCK, acquireCount);
              metric.add(ClusterFlowEvent.BLOCK_REQUEST, 1);
              ClusterServerStatLogUtil.log("flow|block|" + id, acquireCount);
              ClusterServerStatLogUtil.log("flow|block_request|" + id, 1);
  
              return blockedResult();
          }
      }
  
      private static TokenResult blockedResult() {
          return new TokenResult(TokenResultStatus.BLOCKED)
              .setRemaining(0)
              .setWaitInMs(0);
      }
  
      private SimpleClusterFlowChecker() {}
  }
  