@Override
  public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    inFlightRequests.decrementAndGet();
    super.exceptionCaught(ctx, cause);
  }
A handler to track requests stats. For now, it only tracks in-flight request count.
ambry-network/src/main/java/com/github/ambry/network/http2/RequestsStatsHandler.java