code: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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 org.apache.skywalking.oap.server.configuration.consul;
  
  import com.google.common.base.Splitter;
  import com.google.common.net.HostAndPort;
  import com.orbitz.consul.Consul;
  import com.orbitz.consul.KeyValueClient;
  import com.orbitz.consul.cache.KVCache;
  import com.orbitz.consul.model.kv.Value;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Optional;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.stream.Collectors;
  import lombok.extern.slf4j.Slf4j;
  import org.apache.commons.lang3.StringUtils;
  import org.apache.skywalking.oap.server.configuration.api.ConfigTable;
  import org.apache.skywalking.oap.server.configuration.api.ConfigWatcherRegister;
  import org.apache.skywalking.oap.server.configuration.api.GroupConfigTable;
  
  @SuppressWarnings("UnstableApiUsage")
  @Slf4j
  public class ConsulConfigurationWatcherRegister extends ConfigWatcherRegister {
      private static final int DEFAULT_PORT = 8500;
  
      private final KeyValueClient consul;
      private final Map<String, Optional<String>> configItemKeyedByName;
      private final Map<String, KVCache> cachesByKey;
  
      public ConsulConfigurationWatcherRegister(ConsulConfigurationCenterSettings settings) {
          super(settings.getPeriod());
  
          this.configItemKeyedByName = new ConcurrentHashMap<>();
          this.cachesByKey = new ConcurrentHashMap<>();
  
          List<HostAndPort> hostAndPorts = Splitter.on(",")
                                                   .splitToList(settings.getHostAndPorts())
                                                   .parallelStream()
                                                   .map(hostAndPort -> HostAndPort.fromString(hostAndPort)
                                                                                  .withDefaultPort(DEFAULT_PORT))
                                                   .collect(Collectors.toList());
  
          Consul.Builder builder = Consul.builder().withConnectTimeoutMillis(3_000)
                                         .withReadTimeoutMillis(20_000);
  
          if (hostAndPorts.size() == 1) {
              builder.withHostAndPort(hostAndPorts.get(0));
          } else {
              builder.withMultipleHostAndPort(hostAndPorts, 5000);
          }
  
          if (StringUtils.isNotEmpty(settings.getAclToken())) {
              builder.withAclToken(settings.getAclToken());
          }
  
          consul = builder.build().keyValueClient();
      }
  
      @Override
      public Optional<ConfigTable> readConfig(Set<String> keys) {
          removeUninterestedKeys(keys);
  
          registerKeyListeners(keys);
  
          final ConfigTable table = new ConfigTable();
  
          configItemKeyedByName.forEach((key, value) -> {
              if (value.isPresent()) {
                  table.add(new ConfigTable.ConfigItem(key, value.get()));
              } else {
                  table.add(new ConfigTable.ConfigItem(key, null));
              }
          });
  
          return Optional.of(table);
      }
  
      @Override
      public Optional<GroupConfigTable> readGroupConfig(final Set<String> keys) {
          GroupConfigTable groupConfigTable = new GroupConfigTable();
          keys.forEach(key -> {
              GroupConfigTable.GroupConfigItems groupConfigItems = new GroupConfigTable.GroupConfigItems(key);
              groupConfigTable.addGroupConfigItems(groupConfigItems);
              String groupKey = key + "/";
              List<String> groupItemKeys = this.consul.getKeys(groupKey);
              if (groupItemKeys != null) {
                  groupItemKeys.stream().filter(it -> !groupKey.equals(it)).forEach(groupItemKey -> {
                      Optional<String> itemValue = this.consul.getValueAsString(groupItemKey);
                      String itemName = groupItemKey.substring(groupKey.length());
                      groupConfigItems.add(
                          new ConfigTable.ConfigItem(itemName, itemValue.orElse(null)));
                  });
              }
          });
          return Optional.of(groupConfigTable);
      }
  
      private void registerKeyListeners(final Set<String> keys) {
          final Set<String> unregisterKeys = new HashSet<>(keys);
          unregisterKeys.removeAll(cachesByKey.keySet());
  
          unregisterKeys.forEach(key -> {
              KVCache cache = KVCache.newCache(consul, key);
              cache.addListener(newValues -> {
                  Optional<Value> value = newValues.values().stream().filter(it -> key.equals(it.getKey())).findAny();
                  if (value.isPresent()) {
                      onKeyValueChanged(key, value.get().getValueAsString().orElse(null));
                  } else {
                      onKeyValueChanged(key, null);
                  }
              });
              cache.start();
              cachesByKey.put(key, cache);
          });
      }
  
      private void removeUninterestedKeys(final Set<String> interestedKeys) {
          final Set<String> uninterestedKeys = new HashSet<>(cachesByKey.keySet());
          uninterestedKeys.removeAll(interestedKeys);
  
          uninterestedKeys.forEach(k -> {
              KVCache cache = cachesByKey.remove(k);
              if (cache != null) {
                  cache.stop();
              }
          });
      }
  
      private void onKeyValueChanged(String key, String value) {
          if (log.isInfoEnabled()) {
              log.info("Consul config changed: {}: {}", key, value);
          }
  
          configItemKeyedByName.put(key, Optional.ofNullable(value));
      }
  }
  