protected static void incrementCounter(Registry registry, String counterName, String metricId, Http2Frame frame)
{
    long errorCode;
    if (frame instanceof Http2ResetFrame) {
        errorCode = ((Http2ResetFrame) frame).errorCode();
    }
    else if (frame instanceof Http2GoAwayFrame) {
        errorCode = ((Http2GoAwayFrame) frame).errorCode();
    }
    else {
        errorCode = -1;
    }

    registry.counter(counterName,
            "id", metricId,
            "frame", frame.name(),
            "error_code", Long.toString(errorCode))
            .increment();
}
 

@Override
public final void userEventTriggered(ChannelHandlerContext ctx, Object evt) {
    if (evt instanceof Http2ResetFrame) {
        Http2ResetFrame resetFrame = (Http2ResetFrame) evt;
        if (resetFrame.errorCode() == REFUSED_STREAM.code()) {
            ctx.fireExceptionCaught(new H2StreamRefusedException("RST_STREAM received. stream refused"));
        } else {
            ctx.fireExceptionCaught(new H2StreamResetException("RST_STREAM received with error code: " +
                    resetFrame.errorCode()));
        }
    } else {
        ctx.fireUserEventTriggered(evt);
    }
}
 

@Override
protected void channelRead0(ChannelHandlerContext ctx, Http2Frame frame) throws Exception {
    if (frame instanceof Http2DataFrame) {
        onDataRead((Http2DataFrame) frame, ctx);
    } else if (frame instanceof Http2HeadersFrame) {
        onHeadersRead((Http2HeadersFrame) frame, ctx);
        ctx.channel().read();
    } else if (frame instanceof Http2ResetFrame) {
        onRstStreamRead((Http2ResetFrame) frame, ctx);
    } else {
        // TODO this is related to the inbound window update bug. Revisit
        ctx.channel().parent().read();
    }
}
 

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception
{
    if (msg instanceof Http2ResetFrame) {
        // Inform zuul to cancel the request.
        ctx.fireUserEventTriggered(new RequestCancelledEvent());
    }
    else {
        super.channelRead(ctx, msg);
    }
}
 

private void onRstStreamRead(Http2ResetFrame resetFrame, ChannelHandlerContext ctx) throws Http2Exception {
    ctx.fireExceptionCaught(new Http2ResetException(resetFrame.errorCode()));
}