class BrokenUploadInfoHandlerHolder {
		private static HttpFileServerController singleton = new HttpFileServerController();
	}

	/**
	 * constructor
	 */
	private HttpFileServerController() {
		contextMap = new ConcurrentHashMap<String, ChannelHandlerContext>();
	}

	/**
	 * getInstance
	 */
	public static HttpFileServerController getInstance() {
		return BrokenUploadInfoHandlerHolder.singleton;
	}

	/**
	 * mapChannelHandlerContext
	 * 
	 * @param requestId
	 * @param ctx
	 */
	public synchronized void mapChannelHandlerContext(String requestId, ChannelHandlerContext ctx) {
		if (contextMap.containsKey(requestId)) {
			logger.warn("contextMap has already contained the key:" + requestId);
		}

		contextMap.put(requestId, ctx);
	}

	/**
	 * getContext
	 * 
	 * @param requestId
	 * @return
	 */
	public ChannelHandlerContext getChannelHandlerContext(String requestId) {<FILL_FUNCTION_BODY>

		if (!contextMap.containsKey(requestId)) {
			logger.warn("contextMap not contains the key:" + requestId);
			return null;
		}

		return contextMap.get(requestId);
	
<no_super_class>