From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.droids-corp.org (zoll.droids-corp.org [94.23.50.67]) by dpdk.org (Postfix) with ESMTP id 522891B1FA for ; Wed, 15 Nov 2017 09:04:33 +0100 (CET) Received: from lfbn-1-6068-189.w90-110.abo.wanadoo.fr ([90.110.3.189] helo=droids-corp.org) by mail.droids-corp.org with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.84_2) (envelope-from ) id 1eEsmL-00042g-Mu; Wed, 15 Nov 2017 09:10:39 +0100 Received: by droids-corp.org (sSMTP sendmail emulation); Wed, 15 Nov 2017 09:04:24 +0100 Date: Wed, 15 Nov 2017 09:04:24 +0100 From: Olivier MATZ To: "Wiles, Keith" Cc: Adrien Mazarguil , "Wu, Jingjing" , "dev@dpdk.org" , Thomas Monjalon , "Yigit, Ferruh" Message-ID: <20171115080423.um45mrvaupqu2tmb@platinum> References: <1510234868-31053-1-git-send-email-adrien.mazarguil@6wind.com> <48C2CD08-29E1-444C-BF60-B96BE58865A5@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48C2CD08-29E1-444C-BF60-B96BE58865A5@intel.com> User-Agent: NeoMutt/20170113 (1.7.2) Subject: Re: [dpdk-dev] [RFC] cmdline: rework as a wrapper to libedit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 15 Nov 2017 08:04:33 -0000 Hi, On Wed, Nov 15, 2017 at 04:12:07AM +0000, Wiles, Keith wrote: > > > > On Nov 9, 2017, at 5:43 AM, Adrien Mazarguil wrote: > > > > This patch removes all code associated with symbols not internally relied > > on by other DPDK components, makes struct cmdline opaque and then proceeds > > to re-implement the remaining functionality as a wrapper to the editline > > library (also known as libedit) [1]. > > > > Besides adding a new external dependency to its users, its large impact on > > librte_cmdline's API/ABI also warrants a major version number bump. > > > > While librte_cmdline served DPDK well all these years as a small, easy to > > use and self-sufficient interactive command-line handler, it started to > > show its limits with testpmd's flow (rte_flow) command, which required > > support for dynamic tokens and very long commands. > > > > This is the main motivation behind this rework. Long commands often need to > > be displayed on multiple lines, which are not properly supported by > > librte_cmdline's limited terminal handling capabilities, resulting in a > > rather frustrating user experience. > > > > Testpmd being one of the main tools used by PMD developers and given flow > > command lines won't get any shorter, this issue had to be addressed. > > > > Three options were considered: > > > > - Fixing and enhancing librte_cmdline. > > > > The amount of work necessary to add support for edition on multiple lines > > was deemed significant and the result would still have lacked in some > > areas, such as working backspace/delete keys in all terminals (i.e. full > > termcap support). > > > > - Making testpmd directly rely on a more capable library. > > > > All testpmd commands rely on the cmdline_parse interface provided by > > librte_cmdline. This approach would have required either a complete > > rewrite or importing the missing bits from librte_cmdline to wrap them > > around the new library, which naturally led to... > > > > - Converting librte_cmdline as a wrapper to a more capable library. > > > > Let's be honest, interactive command line handling isn't what makes DPDK > > shine. It's also far removed from its core functionality, but is still > > necessary in order to easily implement test and example programs; the > > cmdline_parse interface is particularly good at this. > > > > DPDK actually only relies on cmdline_parse. By removing all the other > > unused interfaces, implementing what remains on top of a different > > terminal-handling library would be quick and easy. > > > > This last approach was chosen for the stated reasons. Libedit is > > well-known, BSD-licensed, widely available [2], used by many projects, does > > everything needed and more [3]. > > > > This rework results in the following changes: > > > > - Removed circular buffer management interface for command history > > (cmdline_cirbuf.c), command history being handled by libedit. > > - Removed raw command-line interpreter (cmdline_rdline.c). > > - Removed raw terminal handler (cmdline_vt100.c). > > - Removed all test/example code for the above. > > - Re-implemented high level interactive and non-interactive command-line > > handlers (cmdline.c and cmdline_socket.c) on top of libedit using its > > native interface, not its readline compatibility layer. > > - Made struct cmdline opaque so that applications relying on librte_cmdline > > do not need to include any libedit headers. > > - The only visible change for most applications besides being linked to > > libedit is they do not have to include cmdline_rdline.h anymore. > > > > As an added bonus, terminal resizing is now automatically handled. > > > > In the future, cmdline_parse could use libedit's advanced tokenizer as > > well to interpret quoted strings and escape sequences. > > > > I do agree that cmdline is getting pretty old and using libedit is one solution around the long commands, but it has a lot more problems IMO. > > I do not agree it has severed DPDK well, just look at test-pmd and the hoops people have to jump thru to get a new command or variation of an existing command integrated into test-pmd it is very difficult. Also if you look at the command sets in test-pmd they are very odd in that similar commands can some times be set up completely different as cmdline is too rigid and difficult to use. > > I had decided to not use the circular buffer code in cmdline as it did have a few problems for what I wanted and decided to write a standard gap buffer scheme used in most editors for lines. I had looked at libedit at one point decided I did not want another dependence for DPDK. I expect even my version does not solve the long line problem, but we can convert to libedit. (and toss my pretty code :-) > > Fixing the long line problem is a very minor issue compared to everything else wrong with cmdline. I would suggest we look at CLI and improve it instead. We can add libedit to CLI and then finish testing the CLI with test-pmd. The first time I converted test-pmd I did remove and simplify the commands, but I was afraid that would cause a lot of problems for testing and scripts that people have written, but it is possible to fix these problems too. > > > I do not think fixing cmdline is the best answer and working to convert over to CLI is the better answer here. On my side, I think this patch goes in the correct direction: - it solves an issue of the command line library - it replaces a specific dpdk code by a well-known library which is widely used Olivier