@Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if (evt instanceof HttpLifecycleChannelHandler.StartEvent) {
            incrementCurrentRequestsInFlight(ctx);
        } else if (evt instanceof CompleteEvent
                && ((CompleteEvent) evt).getReason() == CompleteReason.PIPELINE_REJECT) {
            unSupportedPipeliningCounter.increment();
        } else if (evt instanceof CompleteEvent) {
            decrementCurrentRequestsIfOneInflight(ctx);
        }
        super.userEventTriggered(ctx, evt);
    }
User: michaels@netflix.com
Date: 4/14/16
Time: 3:51 PM
zuul-core/src/main/java/com/netflix/netty/common/metrics/HttpMetricsChannelHandler.java