[GitHub] [incubator-iotdb] jixuan1989 commented on issue #188: [IOTDB-109]Fix native restore tsfile writer if file is complete and append=true

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jixuan1989 commented on issue #188: [IOTDB-109]Fix native restore tsfile writer if file is complete and append=true
URL: https://github.com/apache/incubator-iotdb/pull/188#issuecomment-509256894
 
 
   Well, as the class is renamed as RestorableTsFileIOWriter and does not support append at the end of a complete TsFile anymore, I think we can provide a new function to support appending data at the end of a tsfile:
   
   ```java
     RestorableTsFileIOWriter createRestorableTsFileIOWriter(File file) throws IOException {
       long position = file.length();
   
       try (TsFileSequenceReader reader = new TsFileSequenceReader(file.getAbsolutePath(), false)) {
         // this tsfile is complete
         if (reader.isComplete()) {
           TsFileMetaData metaData = reader.readFileMetadata();
           for (TsDeviceMetadataIndex deviceMetadata : metaData.getDeviceMap().values()) {
             if (position > deviceMetadata.getOffset()){
               position = deviceMetadata.getOffset();
             }
           }
         }
       }
   
       if (position != file.length()) {
         // if the file is complete, we will remove all file metadatas
         try (FileChannel channel = FileChannel.open(Paths.get(file.getAbsolutePath()), StandardOpenOption.WRITE)){
           channel.truncate(position - 1);//remove the last marker.
         }
       }
       return new RestorableTsFileIOWriter(file);
     }
   ```

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