flink判断两个事件之间有没有超时（不使用CEP）

1.为啥不使用cep呢，cep的超时时间设置不好配置化，无法满足扩展要求

2.超时怎么界定。A事件发生后，过了N时间，还没有收到B事件，算超时。

代码如下：

import com.alibaba.fastjson.JSONObject;
import lombok.extern.slf4j.Slf4j;
import org.apache.flink.api.common.state.ValueState;
import org.apache.flink.api.common.state.ValueStateDescriptor;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.functions.KeyedProcessFunction;
import org.apache.flink.util.Collector;

@Slf4j
public class AsyncModelTimeoutHandler extends KeyedProcessFunction<String, JSONObject, JSONObject> {

    private static final long serialVersionUID = -61608451659272532L;
    private transient ValueState<Long> firstDataTime;

    private transient ValueState<Long> secondDataTime;

    private transient ValueState<String> eventType;

    @Override
    public void open(Configuration parameters) throws Exception {
        ValueStateDescriptor<Long> firstDataDescriptor = new ValueStateDescriptor<>("firstDataTime", Long.class);
        firstDataTime = getRuntimeContext().getState(firstDataDescriptor);

        ValueStateDescriptor<Long> secondDataDescriptor = new ValueStateDescriptor<>("secondDataTime", Long.class);
        secondDataTime = getRuntimeContext().getState(secondDataDescriptor);

        ValueStateDescriptor<String> eventTypeDescriptor = new ValueStateDescriptor<>("eventType", String.class);
        eventType = getRuntimeContext().getState(eventTypeDescriptor);
    }


    @Override
    public void processElement(JSONObject value, KeyedProcessFunction<String, JSONObject, JSONObject>.Context ctx, Collector<JSONObject> out) throws Exception {
        Long currentTimestamp = value.getLong("ts");
        if (value.containsKey("timeout")) {
            //异步请求消息
            long timeout = value.getLong("timeout");
            firstDataTime.update(currentTimestamp + timeout);
            eventType.update(value.getString("event"));
            ctx.timerService().registerProcessingTimeTimer(currentTimestamp + timeout);
        } else {
            secondDataTime.update(currentTimestamp);
        }
    }

    @Override
    public void onTimer(long timestamp, KeyedProcessFunction<String, JSONObject, JSONObject>.OnTimerContext ctx, Collector<JSONObject> out) throws Exception {
        Long firstTime = firstDataTime.value();
        Long lastTime = secondDataTime.value();
        if (lastTime == null || (firstTime != null && lastTime >= firstTime)) {
            //超时了
            log.info("AsyncModelTimeoutHandler onTimer handle triggerTime={}, firstTime={}, secondTime={},key={}", timestamp, firstTime, lastTime, ctx.getCurrentKey());
            JSONObject r = new JSONObject();
            r.put("id", ctx.getCurrentKey());
            r.put("judgeTime", timestamp);
            r.put("event", eventType.value());
            out.collect(r);
        }
        firstDataTime.clear();
        secondDataTime.clear();
        eventType.clear();
    }
}