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.nacos.client.naming.cache;
  
  import com.alibaba.fastjson.JSON;
  import com.alibaba.nacos.api.common.Constants;
  import com.alibaba.nacos.api.naming.pojo.Instance;
  import com.alibaba.nacos.api.naming.pojo.ServiceInfo;
  import com.alibaba.nacos.client.naming.utils.CollectionUtils;
  import com.alibaba.nacos.client.utils.StringUtils;
  
  import java.io.BufferedReader;
  import java.io.File;
  import java.io.StringReader;
  import java.net.URLDecoder;
  import java.nio.charset.Charset;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import static com.alibaba.nacos.client.utils.LogUtils.NAMING_LOGGER;
  
  /**
   * @author xuanyin
   */
  public class DiskCache {
  
      public static void write(ServiceInfo dom, String dir) {
  
          try {
              makeSureCacheDirExists(dir);
  
  
              File file = new File(dir, dom.getKeyEncoded());
              if (!file.exists()) {
                  // add another !file.exists() to avoid conflicted creating-new-file from multi-instances
                  if (!file.createNewFile() && !file.exists()) {
                      throw new IllegalStateException("failed to create cache file");
                  }
              }
  
              StringBuilder keyContentBuffer = new StringBuilder("");
  
              String json = dom.getJsonFromServer();
  
              if (StringUtils.isEmpty(json)) {
                  json = JSON.toJSONString(dom);
              }
  
              keyContentBuffer.append(json);
  
              //Use the concurrent API to ensure the consistency.
              ConcurrentDiskUtil.writeFileContent(file, keyContentBuffer.toString(), Charset.defaultCharset().toString());
  
          } catch (Throwable e) {
              NAMING_LOGGER.error("[NA] failed to write cache for dom:" + dom.getName(), e);
          }
      }
  
      public static String getLineSeparator() {
          return System.getProperty("line.separator");
      }
  
      public static Map<String, ServiceInfo> read(String cacheDir) {
          Map<String, ServiceInfo> domMap = new HashMap<String, ServiceInfo>(16);
  
          BufferedReader reader = null;
          try {
              File[] files = makeSureCacheDirExists(cacheDir).listFiles();
              if (files == null || files.length == 0) {
                  return domMap;
              }
  
              for (File file : files) {
                  if (!file.isFile()) {
                      continue;
                  }
  
                  String fileName = URLDecoder.decode(file.getName(), "UTF-8");
  
                  if (!(fileName.endsWith(Constants.SERVICE_INFO_SPLITER + "meta") || fileName.endsWith(
                      Constants.SERVICE_INFO_SPLITER + "special-url"))) {
                      ServiceInfo dom = new ServiceInfo(fileName);
                      List<Instance> ips = new ArrayList<Instance>();
                      dom.setHosts(ips);
  
                      ServiceInfo newFormat = null;
  
                      try {
                          String dataString = ConcurrentDiskUtil.getFileContent(file,
                              Charset.defaultCharset().toString());
                          reader = new BufferedReader(new StringReader(dataString));
  
                          String json;
                          while ((json = reader.readLine()) != null) {
                              try {
                                  if (!json.startsWith("{")) {
                                      continue;
                                  }
  
                                  newFormat = JSON.parseObject(json, ServiceInfo.class);
  
                                  if (StringUtils.isEmpty(newFormat.getName())) {
                                      ips.add(JSON.parseObject(json, Instance.class));
                                  }
                              } catch (Throwable e) {
                                  NAMING_LOGGER.error("[NA] error while parsing cache file: " + json, e);
                              }
                          }
                      } catch (Exception e) {
                          NAMING_LOGGER.error("[NA] failed to read cache for dom: " + file.getName(), e);
                      } finally {
                          try {
                              if (reader != null) {
                                  reader.close();
                              }
                          } catch (Exception e) {
                              //ignore
                          }
                      }
                      if (newFormat != null && !StringUtils.isEmpty(newFormat.getName()) && !CollectionUtils.isEmpty(
                          newFormat.getHosts())) {
                          domMap.put(dom.getKey(), newFormat);
                      } else if (!CollectionUtils.isEmpty(dom.getHosts())) {
                          domMap.put(dom.getKey(), dom);
                      }
                  }
  
              }
          } catch (Throwable e) {
              NAMING_LOGGER.error("[NA] failed to read cache file", e);
          }
  
          return domMap;
      }
  
      private static File makeSureCacheDirExists(String dir) {
          File cacheDir = new File(dir);
          if (!cacheDir.exists() && !cacheDir.mkdirs()) {
              throw new IllegalStateException("failed to create cache dir: " + dir);
          }
  
          return cacheDir;
      }
  }
  