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;
  
  import java.util.Collection;
  
  import com.alibaba.csp.sentinel.cluster.TokenResult;
  import com.alibaba.csp.sentinel.cluster.TokenResultStatus;
  import com.alibaba.csp.sentinel.cluster.flow.rule.ClusterParamFlowRuleManager;
  import com.alibaba.csp.sentinel.cluster.flow.statistic.ClusterParamMetricStatistics;
  import com.alibaba.csp.sentinel.cluster.flow.statistic.limit.GlobalRequestLimiter;
  import com.alibaba.csp.sentinel.cluster.flow.statistic.metric.ClusterParamMetric;
  import com.alibaba.csp.sentinel.cluster.server.log.ClusterServerStatLogUtil;
  import com.alibaba.csp.sentinel.slots.block.ClusterRuleConstant;
  import com.alibaba.csp.sentinel.slots.block.flow.param.ParamFlowRule;
  
  /**
   * @author jialiang.linjl
   * @author Eric Zhao
   * @since 1.4.0
   */
  public final class ClusterParamFlowChecker {
  
      static boolean allowProceed(long flowId) {
          String namespace = ClusterParamFlowRuleManager.getNamespace(flowId);
          return GlobalRequestLimiter.tryPass(namespace);
      }
  
      static TokenResult acquireClusterToken(ParamFlowRule rule, int count, Collection<Object> values) {
          Long id = rule.getClusterConfig().getFlowId();
  
          if (!allowProceed(id)) {
              return new TokenResult(TokenResultStatus.TOO_MANY_REQUEST);
          }
  
          ClusterParamMetric metric = ClusterParamMetricStatistics.getMetric(id);
          if (metric == null) {
              // Unexpected state, return FAIL.
              return new TokenResult(TokenResultStatus.FAIL);
          }
          if (values == null || values.isEmpty()) {
              // Empty parameter list will always pass.
              return new TokenResult(TokenResultStatus.OK);
          }
          double remaining = -1;
          boolean hasPassed = true;
          Object blockObject = null;
          for (Object value : values) {
              double latestQps = metric.getAvg(value);
              double threshold = calcGlobalThreshold(rule, value);
              double nextRemaining = threshold - latestQps - count;
              remaining = nextRemaining;
              if (nextRemaining < 0) {
                  hasPassed = false;
                  blockObject = value;
                  break;
              }
          }
  
          if (hasPassed) {
              for (Object value : values) {
                  metric.addValue(value, count);
              }
              ClusterServerStatLogUtil.log(String.format("param|pass|%d", id));
          } else {
              ClusterServerStatLogUtil.log(String.format("param|block|%d|%s", id, blockObject));
          }
          if (values.size() > 1) {
              // Remaining field is unsupported for multi-values.
              remaining = -1;
          }
  
          return hasPassed ? newPassResponse((int)remaining): newBlockResponse();
      }
  
      private static TokenResult newPassResponse(int remaining) {
          return new TokenResult(TokenResultStatus.OK)
              .setRemaining(remaining)
              .setWaitInMs(0);
      }
  
      private static TokenResult newBlockResponse() {
          return new TokenResult(TokenResultStatus.BLOCKED)
              .setRemaining(0)
              .setWaitInMs(0);
      }
  
      private static double calcGlobalThreshold(ParamFlowRule rule, Object value) {
          double count = getRawThreshold(rule, value);
          switch (rule.getClusterConfig().getThresholdType()) {
              case ClusterRuleConstant.FLOW_THRESHOLD_GLOBAL:
                  return count;
              case ClusterRuleConstant.FLOW_THRESHOLD_AVG_LOCAL:
              default:
                  int connectedCount = ClusterParamFlowRuleManager.getConnectedCount(rule.getClusterConfig().getFlowId());
                  return count * connectedCount;
          }
      }
  
      private static double getRawThreshold(ParamFlowRule rule, Object value) {
          Integer itemCount = rule.retrieveExclusiveItemCount(value);
          if (itemCount == null) {
              return rule.getCount();
          } else {
              return itemCount;
          }
      }
  
      private ClusterParamFlowChecker() {}
  }
  