private String getMetaLogFileName(final String baseLogFileName, final int mainLogId) {
    String metaLogFile = null;
    int extIndex = baseLogFileName.lastIndexOf('.');
    String ext = "";
    if (extIndex != -1) {
      ext = baseLogFileName.substring(extIndex);
      metaLogFile = baseLogFileName.substring(0, extIndex);
    }
    String fileName = new File(metaLogFile).getName();
    String parent = new File(metaLogFile).getParent();

    metaLogFile = "meta-" + fileName + rollingFileHandler.formatId(mainLogId) + ext;
    if (parent != null) {
      metaLogFile = parent + File.separator + metaLogFile;
    }
    return metaLogFile;
  }
Call when the config changes at runtime.
geode-core/src/main/java/org/apache/geode/internal/logging/ManagerLogWriter.java