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.demo.file.rule;
  
  import java.io.File;
  import java.util.List;
  
  import com.alibaba.csp.sentinel.datasource.FileRefreshableDataSource;
  import com.alibaba.csp.sentinel.datasource.FileWritableDataSource;
  import com.alibaba.csp.sentinel.datasource.ReadableDataSource;
  import com.alibaba.csp.sentinel.datasource.WritableDataSource;
  import com.alibaba.csp.sentinel.init.InitFunc;
  import com.alibaba.csp.sentinel.slots.block.flow.FlowRule;
  import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleManager;
  import com.alibaba.csp.sentinel.transport.util.WritableDataSourceRegistry;
  import com.alibaba.fastjson.JSON;
  import com.alibaba.fastjson.TypeReference;
  
  /**
   * <p>
   * A sample showing how to register readable and writable data source via Sentinel init SPI mechanism.
   * </p>
   * <p>
   * To activate this, you can add the class name to `com.alibaba.csp.sentinel.init.InitFunc` file
   * in `META-INF/services/` directory of the resource directory. Then the data source will be automatically
   * registered during the initialization of Sentinel.
   * </p>
   *
   * @author Eric Zhao
   */
  public class FileDataSourceInit implements InitFunc {
  
      @Override
      public void init() throws Exception {
          // A fake path.
          String flowRuleDir = System.getProperty("user.home") + File.separator + "sentinel" + File.separator + "rules";
          String flowRuleFile = "flowRule.json";
          String flowRulePath = flowRuleDir + File.separator + flowRuleFile;
  
          ReadableDataSource<String, List<FlowRule>> ds = new FileRefreshableDataSource<>(
              flowRulePath, source -> JSON.parseObject(source, new TypeReference<List<FlowRule>>() {})
          );
          // Register to flow rule manager.
          FlowRuleManager.register2Property(ds.getProperty());
  
          WritableDataSource<List<FlowRule>> wds = new FileWritableDataSource<>(flowRulePath, this::encodeJson);
          // Register to writable data source registry so that rules can be updated to file
          // when there are rules pushed from the Sentinel Dashboard.
          WritableDataSourceRegistry.registerFlowDataSource(wds);
      }
  
      private <T> String encodeJson(T t) {
          return JSON.toJSONString(t);
      }
  }
  