@Override
    public void readIndex(ReadOnlyOption readOnlyOptions, byte[] requestContext, ReadIndexClosure done) {
        if (this.shutdownLatch != null) {
            ThreadPoolsFactory.runClosureInThread(this.groupId, done, new Status(RaftError.ENODESHUTDOWN,
                "Node is shutting down."));
            throw new IllegalStateException("Node is shutting down");
        }
        Requires.requireNonNull(done, "Null closure");
        this.readOnlyService.addRequest(readOnlyOptions, requestContext, done);
    }
Returns the JRaft service factory for current node.
@since 1.2.6
@return the service factory
jraft-core/src/main/java/com/alipay/sofa/jraft/core/NodeImpl.java