From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.tuxdriver.com (charlotte.tuxdriver.com [70.61.120.58]) by dpdk.org (Postfix) with ESMTP id 32DF058EE for ; Tue, 4 Nov 2014 00:33:27 +0100 (CET) Received: from [2001:470:8:a08:215:ff:fecc:4872] (helo=localhost) by smtp.tuxdriver.com with esmtpsa (TLSv1:AES128-SHA:128) (Exim 4.63) (envelope-from ) id 1XlRGa-00046p-K8; Mon, 03 Nov 2014 18:42:38 -0500 Date: Mon, 3 Nov 2014 18:42:30 -0500 From: Neil Horman To: Stephen Hemminger Message-ID: <20141103234230.GA2660@localhost.localdomain> References: <1414967308-69530-1-git-send-email-keith.wiles@windriver.com> <20141103104129.GA4840@bricha3-MOBL3> <307F2C60-7638-40C8-A9BC-DC3EE3D59F8C@windriver.com> <20141103141658.GA6964@bricha3-MOBL3> <7D39110F-D305-4C48-8BD6-37F6DCD2E434@windriver.com> <20141103160602.GA6625@localhost.localdomain> <6F166021-567F-4B30-8EAE-EDB68A86C6CC@windriver.com> <20141103152650.262e4da3@urahara> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20141103152650.262e4da3@urahara> User-Agent: Mutt/1.5.23 (2014-03-12) X-Spam-Score: -2.9 (--) X-Spam-Status: No Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [PATCH] Add external parser support for unknown commands. X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 03 Nov 2014 23:33:27 -0000 On Mon, Nov 03, 2014 at 03:26:50PM -0800, Stephen Hemminger wrote: > On Mon, 3 Nov 2014 16:50:15 +0000 > "Wiles, Roger Keith" wrote: > > > > > > On Nov 3, 2014, at 10:06 AM, Neil Horman wrote: > > > > > > On Mon, Nov 03, 2014 at 02:25:51PM +0000, Wiles, Roger Keith wrote: > > >> > > >>> On Nov 3, 2014, at 8:16 AM, Bruce Richardson wrote: > > >>> > > >>> On Mon, Nov 03, 2014 at 02:08:46PM +0000, Wiles, Roger Keith wrote: > > >>>> > > >>>>> On Nov 3, 2014, at 4:41 AM, Bruce Richardson wrote: > > >>>>> > > >>>>> On Sun, Nov 02, 2014 at 04:28:28PM -0600, Keith Wiles wrote: > > >>>>>> Allow for a external parser to handle the command line if the > > >>>>>> command is not found and the developer has called the routine > > >>>>>> int cmdline_set_external_parser(struct cmdline * cl, > > >>>>>> cmdline_external_parser_t parser); > > >>>>>> function to set the function pointer. > > >>>>>> > > >>>>>> The function for the external parser function should return CMDLINE_PARSE_NOMATCH > > >>>>>> if not able to match the command requested or zero is handled. > > >>>>>> > > >>>>>> Prototype of external routine: > > >>>>>> int (*cmdline_external_parser_t)(struct cmdline * cl, const char * buy); > > >>>>>> > > >>>>>> Signed-off-by: Keith Wiles > > >>>>> > > >>>>> Hi Keith, > > >>>>> > > >>>>> what is the expected use case for this? Is it for embedding other programming languages alongside the existing DPDK command-line or some other purpose? [Perhaps the use case could be called out in the patch description] > > >>>> > > >>>> Hi Bruce, > > >>>> > > >>>> I guess the external parser could be used for other programming languages, but the case I was looking at was to provide a default escape from the command line parser to allow my application to handle the commands not understood by the parser. Now that you point it out I could use something like ‘%’ to execute a single line of script code, which is a good idea (thanks). > > >>>> > > >>>> One case I am looking at is when you want to execute a command and do not want to add the support into the commands.c file for every possible command. Take the case where you have a bunch of scripts (Lua) in a directory much like a bin directory. Then you could type foo.lua or foo on the command line and execute the foo.lua having the application detect you want to load and run a Lua script after it has finished parsing for the builtin commands. > > >>>> > > >>>> For Pktgen I had to add a command called ‘run ’ to support running a script with arguments. I also needed to add a argvlist type to cmdline to not error out on that command and split up the args into a argv list like format. (Maybe I need to submit that code??) It seemed more straight forward to just pass the command line to the application to run the command. I understand that seems like a minor point, but it does make it easier to use and to support the features I want to support in my PoC. > > >>>> > > >>>> Using this method you can just type the name instead of something like ‘run foo.lua’ or just ‘run foo’ and let the code figure out what to run. I have more plans for this features as well and have not finished the basic PoC yet. If you want a peek I can show you what I am working on currently. > > >>>> > > >>>> Does this help and do I really need to add all of this to the commit message :-) > > >>>> > > >>> Thanks for the explanation. However, if you are looking to have the application handle a bunch of commands itself, why does it need to use the commandline library at all? Why not just have the app handle all the commands instead of some of them? > > >> > > >> I guess that would be reasonable, but then I would have to add support for all of the command line parsing being done in the cmdline code. Think of this as a default case for the parser and to me that makes more sense then just doing my own command line design. In the cmdline code you guys provided is a lot of features like history, control key support, arg parsing (IP, MAC) and many others. I would rather not have to write that code myself. > > >> > > >> The default case is the same behavior today, with giving a no match error unless they add the external parser. > > > > > > It seems alot simpler than that to me. Looking at the test applications, the > > > command line parser expects the application to create an array of > > > cmdline_parse_ctx_t structures to support new option parsing. If your goal is > > > to support other languages, it seems to make more sense to just use foreign > > > language bindings to merge your coding language support with the DPDK > > > (ostensibly you will already have to do that if you want to use other parts of > > > the DPDK). > > Hi Neil, > > > > A true language binding like Lua or one of those other languages :-) you are correct to believe binding directly using ‘C’ code is the right solution . In Pktgen I use Lua as the direct language binding and extend Lua with specific Pktgen functions. > > > > What I am doing here is to add a default case to cmdline code, which just happens to allow me to parse the cmdline in the application. Being able to execute say a line of script code is not really the requirement IMO. Being able to extend the cmdline code with a default case is a good feature and allows the developer to extend cmdline for some simple cases. The cmdline code is kind of simple, but does require a fair amount of structures, code and understanding to write a complex extendable command line interface. It does seem hard to find a clean, simple and usable embedded command line code base is not very easy to locate. > > > > Adding a true language binding really requires using code to extend the language as I did with Lua and Pktgen. It could have been done with any language I just picked Lua, but the patch does not really add support for a language other then giving some support for someone to handle the no_match case. > > > > The use case for this feature is not just for Pktgen, but another solution I hope everyone will find useful when I get it more complete. > > > > Thanks > > ++Keith > > > > PS. on a different topic I was thinking about suggesting and writing a patch to add Lua with DPDK specific binding and extensions. (also allowing those `other` languages too :-) Being able to use a scripting language and be able to call DPDK API’s could be useful. How useful not sure at this time. (If you want to talk about this topic please start a new thread). > > > > > > Am I missing something? > > > Neil > > > > > > > > >>> > > >>> /Bruce > > >> > > >> Keith Wiles, Principal Technologist with CTO office, Wind River mobile 972-213-5533 > > > > Keith Wiles, Principal Technologist with CTO office, Wind River mobile 972-213-5533 > > I wouldn't invest a lot of sweat in the command line parser. > The one in the DPDK is "good enough" for what it needs to do, but really isn't > very complete and flexible. Seems like the kind of thing that doesn't really even > need to be in DPDK. Better off being part of some other library. > Well, something needs to be there to parse the libraries' common options, though I agree, making eal_cmdline just a registration frontend to getopt or getopt_long would be sufficient. Neil