content: /*
   * Copyright 1999-2023 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.utils;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.File;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.RandomAccessFile;
  import java.nio.ByteBuffer;
  import java.nio.CharBuffer;
  import java.nio.channels.FileChannel;
  import java.nio.channels.FileLock;
  import java.nio.charset.Charset;
  import java.nio.charset.CharsetDecoder;
  
  /**
   * Concurrent Disk util.
   *
   * @author nkorange
   */
  public class ConcurrentDiskUtil {
      
      private static final Logger LOGGER = LoggerFactory.getLogger(ConcurrentDiskUtil.class);
      
      private static final String READ_ONLY = "r";
      
      private static final String READ_WRITE = "rw";
      
      private static final int RETRY_COUNT = 10;
      
      private static final int SLEEP_BASETIME = 10;
      
      /**
       * get file content.
       *
       * @param path        file path
       * @param charsetName charsetName
       * @return content
       * @throws IOException IOException
       */
      public static String getFileContent(String path, String charsetName) throws IOException {
          File file = new File(path);
          return getFileContent(file, charsetName);
      }
      
      /**
       * get file content.
       *
       * @param file        file
       * @param charsetName charsetName
       * @return content
       * @throws IOException IOException
       */
      public static String getFileContent(File file, String charsetName) throws IOException {
          try (RandomAccessFile fis = new RandomAccessFile(file, READ_ONLY);
                  FileChannel fcin = fis.getChannel();
                  FileLock rlock = tryLock(file, fcin, true)) {
              int fileSize = (int) fcin.size();
              ByteBuffer byteBuffer = ByteBuffer.allocate(fileSize);
              fcin.read(byteBuffer);
              byteBuffer.flip();
              return byteBufferToString(byteBuffer, charsetName);
          }
      }
      
      /**
       * write file content.
       *
       * @param path        file path
       * @param content     content
       * @param charsetName charsetName
       * @return whether write ok
       * @throws IOException IOException
       */
      public static Boolean writeFileContent(String path, String content, String charsetName) throws IOException {
          File file = new File(path);
          return writeFileContent(file, content, charsetName);
      }
      
      /**
       * write file content.
       *
       * @param file        file
       * @param content     content
       * @param charsetName charsetName
       * @return whether write ok
       * @throws IOException IOException
       */
      public static Boolean writeFileContent(File file, String content, String charsetName) throws IOException {
          
          if (!file.exists() && !file.createNewFile()) {
              return false;
          }
          try (RandomAccessFile raf = new RandomAccessFile(file, READ_WRITE);
                  FileChannel channel = raf.getChannel();
                  FileLock lock = tryLock(file, channel, false)) {
              byte[] contentBytes = content.getBytes(charsetName);
              ByteBuffer sendBuffer = ByteBuffer.wrap(contentBytes);
              while (sendBuffer.hasRemaining()) {
                  channel.write(sendBuffer);
              }
              channel.truncate(contentBytes.length);
          } catch (FileNotFoundException e) {
              throw new IOException("file not exist");
          }
          return true;
      }
      
      /**
       * transfer ByteBuffer to String.
       *
       * @param buffer      buffer
       * @param charsetName charsetName
       * @return String
       * @throws IOException IOException
       */
      public static String byteBufferToString(ByteBuffer buffer, String charsetName) throws IOException {
          Charset charset = Charset.forName(charsetName);
          CharsetDecoder decoder = charset.newDecoder();
          CharBuffer charBuffer = decoder.decode(buffer.asReadOnlyBuffer());
          return charBuffer.toString();
      }
      
      private static void sleep(int time) {
          try {
              Thread.sleep(time);
          } catch (InterruptedException e) {
              LOGGER.warn("sleep wrong", e);
              // set the interrupted flag
              Thread.currentThread().interrupt();
          }
      }
      
      private static FileLock tryLock(File file, FileChannel channel, boolean shared) throws IOException {
          FileLock result = null;
          int i = 0;
          do {
              try {
                  result = channel.tryLock(0L, Long.MAX_VALUE, shared);
              } catch (Exception e) {
                  ++i;
                  if (i > RETRY_COUNT) {
                      LOGGER.error("[NA] lock " + file.getName() + " fail;retryed time: " + i, e);
                      throw new IOException("lock " + file.getAbsolutePath() + " conflict");
                  }
                  sleep(SLEEP_BASETIME * i);
                  LOGGER.warn("lock " + file.getName() + " conflict;retry time: " + i);
              }
          } while (null == result);
          return result;
      }
      
  }
  