void createOplogs(boolean needsOplogs, Map<File, DirectoryHolder> backupFiles) {
    LongOpenHashSet foundCrfs = new LongOpenHashSet();
    LongOpenHashSet foundDrfs = new LongOpenHashSet();

    for (Map.Entry<File, DirectoryHolder> entry : backupFiles.entrySet()) {
      File file = entry.getKey();
      String absolutePath = file.getAbsolutePath();

      int underscorePosition = absolutePath.lastIndexOf('_');
      int pointPosition = absolutePath.lastIndexOf('.');
      String oplogIdString = absolutePath.substring(underscorePosition + 1, pointPosition);
      long oplogId = Long.parseLong(oplogIdString);

      maxRecoveredOplogId = Math.max(maxRecoveredOplogId, oplogId);

      // here look diskinit file and check if this opid already deleted or not
      // if deleted then don't process it.

      if (Oplog.isCRFFile(file.getName())) {
        if (!isCrfOplogIdPresent(oplogId)) {
          deleteFileOnRecovery(file);
          try {
            String krfFileName = Oplog.getKRFFilenameFromCRFFilename(file.getAbsolutePath());
            File krfFile = new File(krfFileName);
            deleteFileOnRecovery(krfFile);
          } catch (Exception ignore) {
            // ignore
          }
          // this file we unable to delete earlier
          continue;
        }

      } else if (Oplog.isDRFFile(file.getName())) {
        if (!isDrfOplogIdPresent(oplogId)) {
          deleteFileOnRecovery(file);
          // this file we unable to delete earlier
          continue;
        }
      }

      Oplog oplog = getChild(oplogId);
      if (oplog == null) {
        oplog = new Oplog(oplogId, this);
        addRecoveredOplog(oplog);
      }

      if (oplog.addRecoveredFile(file, entry.getValue())) {
        foundCrfs.add(oplogId);
      } else {
        foundDrfs.add(oplogId);
      }
    }
    if (needsOplogs) {
      verifyOplogs(foundCrfs, foundDrfs);
    }
  }
Get the oplog specified

@param id int oplogId to be got
@return Oplogs the oplog corresponding to the oplodId, id
geode-core/src/main/java/org/apache/geode/internal/cache/PersistentOplogSet.java