> On Nov 9, 2017, at 5:43 AM, Adrien Mazarguil <adrien.mazarg...@6wind.com> > 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. Regards, Keith
