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.config.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;op file with file lock
   *
   * @author configCenter
   */
  public class ConcurrentDiskUtil {
  
      /**
       * 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 {
          RandomAccessFile fis = null;
          FileLock rlock = null;
          try {
              fis = new RandomAccessFile(file, "r");
              FileChannel fcin = fis.getChannel();
              int i = 0;
              do {
                  try {
                      rlock = fcin.tryLock(0L, Long.MAX_VALUE, true);
                  } catch (Exception e) {
                      ++i;
                      if (i > RETRY_COUNT) {
                          LOGGER.error("read {} fail;retryed time:{}",
                              file.getName(), i);
                          throw new IOException("read " + file.getAbsolutePath()
                              + " conflict");
                      }
                      sleep(SLEEP_BASETIME * i);
                      LOGGER.warn("read {} conflict;retry time:{}", file.getName(),
                          i);
                  }
              } while (null == rlock);
              int fileSize = (int)fcin.size();
              ByteBuffer byteBuffer = ByteBuffer.allocate(fileSize);
              fcin.read(byteBuffer);
              byteBuffer.flip();
              return byteBufferToString(byteBuffer, charsetName);
          } finally {
              if (rlock != null) {
                  rlock.release();
                  rlock = null;
              }
              if (fis != null) {
                  fis.close();
                  fis = null;
              }
          }
      }
  
      /**
       * 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()) {
              boolean isCreateOk = file.createNewFile();
              if (!isCreateOk) {
                  return false;
              }
          }
          FileChannel channel = null;
          FileLock lock = null;
          RandomAccessFile raf = null;
          try {
              raf = new RandomAccessFile(file, "rw");
              channel = raf.getChannel();
              int i = 0;
              do {
                  try {
                      lock = channel.tryLock();
                  } catch (Exception e) {
                      ++i;
                      if (i > RETRY_COUNT) {
                          LOGGER.error("write {} fail;retryed time:{}",
                              file.getName(), i);
                          throw new IOException("write " + file.getAbsolutePath()
                              + " conflict");
                      }
                      sleep(SLEEP_BASETIME * i);
                      LOGGER.warn("write {} conflict;retry time:{}", file.getName(),
                          i);
                  }
              } while (null == lock);
  
              ByteBuffer sendBuffer = ByteBuffer.wrap(content
                  .getBytes(charsetName));
              while (sendBuffer.hasRemaining()) {
                  channel.write(sendBuffer);
              }
              channel.truncate(content.length());
          } catch (FileNotFoundException e) {
              throw new IOException("file not exist");
          } finally {
              if (lock != null) {
                  try {
                      lock.release();
                      lock = null;
                  } catch (IOException e) {
                      LOGGER.warn("close wrong", e);
                  }
              }
              if (channel != null) {
                  try {
                      channel.close();
                      channel = null;
                  } catch (IOException e) {
                      LOGGER.warn("close wrong", e);
                  }
              }
              if (raf != null) {
                  try {
                      raf.close();
                      raf = null;
                  } catch (IOException e) {
                      LOGGER.warn("close wrong", e);
                  }
              }
  
          }
          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 = null;
          CharsetDecoder decoder = null;
          CharBuffer charBuffer = null;
          charset = Charset.forName(charsetName);
          decoder = charset.newDecoder();
          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);
          }
      }
  
      private static final Logger LOGGER = LoggerFactory.getLogger(ConcurrentDiskUtil.class);
      static final int RETRY_COUNT = 10;
      /**
       * ms
       */
      static final int SLEEP_BASETIME = 10;
  }
  