private static SignalAccessor getSignalAccessor0() {
        return hasSignal0() ? new SignalAccessor() : null;
    }
Registers user signal handlers.

@param signalName a signal name
@param handlers   user signal handlers
@return true if support on current platform
jraft-core/src/main/java/com/alipay/sofa/jraft/util/SignalHelper.java