public static int levelNameToCode(String levelName) {
    if ("all".equalsIgnoreCase(levelName)) {
      return ALL_LEVEL;
    }
    if ("finest".equalsIgnoreCase(levelName) || "trace".equalsIgnoreCase(levelName)) {
      return FINEST_LEVEL;
    }
    if ("finer".equalsIgnoreCase(levelName)) {
      return FINER_LEVEL;
    }
    if ("fine".equalsIgnoreCase(levelName) || "debug".equalsIgnoreCase(levelName)) {
      return FINE_LEVEL;
    }
    if ("config".equalsIgnoreCase(levelName)) {
      return CONFIG_LEVEL;
    }
    if ("info".equalsIgnoreCase(levelName)) {
      return INFO_LEVEL;
    }
    if ("warning".equalsIgnoreCase(levelName) || "warn".equalsIgnoreCase(levelName)) {
      return WARNING_LEVEL;
    }
    if ("error".equalsIgnoreCase(levelName)) {
      return ERROR_LEVEL;
    }
    if ("severe".equalsIgnoreCase(levelName) || "fatal".equalsIgnoreCase(levelName)) {
      return SEVERE_LEVEL;
    }
    if ("none".equalsIgnoreCase(levelName)) {
      return NONE_LEVEL;
    }
    try {
      if (levelName.startsWith("level-")) {
        String levelValue = levelName.substring("level-".length());
        return Integer.parseInt(levelValue);
      }
    } catch (NullPointerException | NumberFormatException ignore) {
      // ignored
    }
    throw new IllegalArgumentException(
        "Unknown log-level \"" + levelName + "\". Valid levels are: " + join(levelNames) + ".");
  }
Gets the level code for the given <code>levelName</code>.

@throws IllegalArgumentException if an unknown level name is given.
geode-core/src/main/java/org/apache/geode/internal/logging/LogWriterImpl.java