public void addFailStats(String key, int failCnt) {
        if (isStopped()) {
            return;
        }
        statsUnits[getWriteIndex()].addFailCnt(key, failCnt);
    }
Add failure statistic

@param key  the statistic key
@param failCnt  the failure count
inlong-dataproxy/dataproxy-source/src/main/java/org/apache/inlong/dataproxy/metrics/stats/MonitorIndex.java