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.dashboard.repository.metric;
  
  import com.alibaba.csp.sentinel.dashboard.datasource.entity.MetricEntity;
  import com.alibaba.csp.sentinel.util.StringUtil;
  import com.alibaba.csp.sentinel.util.TimeUtil;
  import org.springframework.stereotype.Component;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.locks.ReentrantReadWriteLock;
  import java.util.stream.Collectors;
  
  /**
   * Caches metrics data in a period of time in memory.
   *
   * @author Carpenter Lee
   * @author Eric Zhao
   */
  @Component
  public class InMemoryMetricsRepository implements MetricsRepository<MetricEntity> {
  
      private static final long MAX_METRIC_LIVE_TIME_MS = 1000 * 60 * 5;
  
      /**
       * {@code app -> resource -> timestamp -> metric}
       */
      private Map<String, Map<String, LinkedHashMap<Long, MetricEntity>>> allMetrics = new ConcurrentHashMap<>();
  
      private final ReentrantReadWriteLock readWriteLock = new ReentrantReadWriteLock();
  
  
      @Override
      public void save(MetricEntity entity) {
          if (entity == null || StringUtil.isBlank(entity.getApp())) {
              return;
          }
          readWriteLock.writeLock().lock();
          try {
              allMetrics.computeIfAbsent(entity.getApp(), e -> new HashMap<>(16))
                      .computeIfAbsent(entity.getResource(), e -> new LinkedHashMap<Long, MetricEntity>() {
                          @Override
                          protected boolean removeEldestEntry(Entry<Long, MetricEntity> eldest) {
                              // Metric older than {@link #MAX_METRIC_LIVE_TIME_MS} will be removed.
                              return eldest.getKey() < TimeUtil.currentTimeMillis() - MAX_METRIC_LIVE_TIME_MS;
                          }
                      }).put(entity.getTimestamp().getTime(), entity);
          } finally {
              readWriteLock.writeLock().unlock();
          }
  
      }
  
      @Override
      public void saveAll(Iterable<MetricEntity> metrics) {
          if (metrics == null) {
              return;
          }
          readWriteLock.writeLock().lock();
          try {
              metrics.forEach(this::save);
          } finally {
              readWriteLock.writeLock().unlock();
          }
      }
  
      @Override
      public List<MetricEntity> queryByAppAndResourceBetween(String app, String resource,
                                                             long startTime, long endTime) {
          List<MetricEntity> results = new ArrayList<>();
          if (StringUtil.isBlank(app)) {
              return results;
          }
          Map<String, LinkedHashMap<Long, MetricEntity>> resourceMap = allMetrics.get(app);
          if (resourceMap == null) {
              return results;
          }
          LinkedHashMap<Long, MetricEntity> metricsMap = resourceMap.get(resource);
          if (metricsMap == null) {
              return results;
          }
          readWriteLock.readLock().lock();
          try {
              for (Entry<Long, MetricEntity> entry : metricsMap.entrySet()) {
                  if (entry.getKey() >= startTime && entry.getKey() <= endTime) {
                      results.add(entry.getValue());
                  }
              }
              return results;
          } finally {
              readWriteLock.readLock().unlock();
          }
      }
  
      @Override
      public List<String> listResourcesOfApp(String app) {
          List<String> results = new ArrayList<>();
          if (StringUtil.isBlank(app)) {
              return results;
          }
          // resource -> timestamp -> metric
          Map<String, LinkedHashMap<Long, MetricEntity>> resourceMap = allMetrics.get(app);
          if (resourceMap == null) {
              return results;
          }
          final long minTimeMs = System.currentTimeMillis() - 1000 * 60;
          Map<String, MetricEntity> resourceCount = new ConcurrentHashMap<>(32);
  
          readWriteLock.readLock().lock();
          try {
              for (Entry<String, LinkedHashMap<Long, MetricEntity>> resourceMetrics : resourceMap.entrySet()) {
                  for (Entry<Long, MetricEntity> metrics : resourceMetrics.getValue().entrySet()) {
                      if (metrics.getKey() < minTimeMs) {
                          continue;
                      }
                      MetricEntity newEntity = metrics.getValue();
                      if (resourceCount.containsKey(resourceMetrics.getKey())) {
                          MetricEntity oldEntity = resourceCount.get(resourceMetrics.getKey());
                          oldEntity.addPassQps(newEntity.getPassQps());
                          oldEntity.addRtAndSuccessQps(newEntity.getRt(), newEntity.getSuccessQps());
                          oldEntity.addBlockQps(newEntity.getBlockQps());
                          oldEntity.addExceptionQps(newEntity.getExceptionQps());
                          oldEntity.addCount(1);
                      } else {
                          resourceCount.put(resourceMetrics.getKey(), MetricEntity.copyOf(newEntity));
                      }
                  }
              }
              // Order by last minute b_qps DESC.
              return resourceCount.entrySet()
                      .stream()
                      .sorted((o1, o2) -> {
                          MetricEntity e1 = o1.getValue();
                          MetricEntity e2 = o2.getValue();
                          int t = e2.getBlockQps().compareTo(e1.getBlockQps());
                          if (t != 0) {
                              return t;
                          }
                          return e2.getPassQps().compareTo(e1.getPassQps());
                      })
                      .map(Entry::getKey)
                      .collect(Collectors.toList());
          } finally {
              readWriteLock.readLock().unlock();
          }
      }
  }
  