/**
  * Выполняет фиксацию изменений.
  *
  * @return Число записанных изменений.
  * @throws java.io.IOException если произошла ошибка ввода/вывода. Целостность таблицы не
  *     гарантируется.
  */
 @Override
 public int commit() throws IOException {
   int numberOfCommittedChanges = uncommittedChanges();
   Set<Map.Entry<String, Storeable>> dbSet = tableIndexedData.entrySet();
   for (int nDir = 0; nDir < 16; ++nDir) {
     for (int nFile = 0; nFile < 16; ++nFile) {
       if (tableFileModified[nDir][nFile]) {
         if (tableFiles[nDir][nFile] == null) {
           File subDir = new File(tableRootDir, Integer.toString(nDir) + ".dir");
           File subFile = new File(subDir, Integer.toString(nFile) + ".dat");
           if (!subDir.exists()) {
             if (!subDir.mkdir()) {
               throw new IllegalStateException("Sub dir was not created");
             }
           }
           tableFiles[nDir][nFile] = new TableFile(subFile);
         }
         List<TableFile.Entry> fileData = new ArrayList<>();
         Iterator<Map.Entry<String, Storeable>> iter = dbSet.iterator();
         while (iter.hasNext()) {
           Map.Entry<String, Storeable> tempMapEntry = iter.next();
           HashcodeDestination dest = new HashcodeDestination(tempMapEntry.getKey());
           if (dest.getDir() == nDir && dest.getFile() == nFile) {
             fileData.add(
                 new TableFile.Entry(
                     tempMapEntry.getKey(),
                     tableProvider.serialize(this, tempMapEntry.getValue())));
           }
         }
         tableFiles[nDir][nFile].writeEntries(fileData);
         tableFileModified[nDir][nFile] = false;
       }
     }
   }
   tableOnDisk.clear();
   tableOnDisk.putAll(tableIndexedData);
   return numberOfCommittedChanges;
 }
 private void index() {
   File[] subDirsList = tableRootDir.listFiles();
   if (subDirsList != null) {
     for (File subDir : subDirsList) {
       int numberOfSubDir;
       if (subDir.getName().equals(SignatureFile.signatureFileName)) {
         continue;
       }
       if (!subDir.isDirectory()) {
         throw new IllegalStateException("In table root dir found object is not a directory");
       }
       String[] tableSubDirName = subDir.getName().split("[.]");
       try {
         numberOfSubDir = Integer.parseInt(tableSubDirName[0]);
       } catch (NumberFormatException e) {
         throw new IllegalStateException("Table root directory contains not 0.dir ... 15.dir");
       }
       if (numberOfSubDir < 0
           || numberOfSubDir > 15
           || !tableSubDirName[1].equals("dir")
           || tableSubDirName.length != 2) {
         throw new IllegalStateException("Table root directory contains not 0.dir ... 15.dir");
       }
       File[] subFilesList = subDir.listFiles();
       if (subFilesList != null && subFilesList.length == 0) {
         throw new IllegalStateException("data base contains empty dir");
       }
       if (subFilesList != null) {
         for (File subFile : subFilesList) {
           int numberOfSubFile;
           if (!subFile.isFile()) {
             throw new IllegalStateException("In table sub dir found object is not a file");
           }
           String[] dbFileName = subFile.getName().split("[.]");
           try {
             numberOfSubFile = Integer.parseInt(dbFileName[0]);
           } catch (NumberFormatException e) {
             throw new IllegalStateException("Table sub directory contains not 0.dat ... 15.dat");
           }
           if (numberOfSubFile < 0
               || numberOfSubFile > 15
               || !dbFileName[1].equals("dat")
               || dbFileName.length != 2) {
             throw new IllegalStateException("Table sub directory contains not 0.dat ... 15.dat");
           } else if (subFile.length() == 0) {
             throw new IllegalStateException("Empty file in sub dir");
           } else {
             tableFiles[numberOfSubDir][numberOfSubFile] = new TableFile(subFile);
             List<TableFile.Entry> fileData =
                 tableFiles[numberOfSubDir][numberOfSubFile].readEntries();
             for (TableFile.Entry i : fileData) {
               HashcodeDestination dest = new HashcodeDestination(i.getKey());
               if (dest.getFile() != numberOfSubFile || dest.getDir() != numberOfSubDir) {
                 throw new IllegalStateException("Wrong key placement");
               }
               try {
                 tableIndexedData.put(i.getKey(), tableProvider.deserialize(this, i.getValue()));
               } catch (ParseException e) {
                 throw new IllegalStateException("Can't deserialize", e);
               }
             }
           }
         }
       }
     }
   }
   tableOnDisk = new HashMap<>(tableIndexedData);
 }