Hi, On Wed, Nov 15, 2017 at 04:12:07AM +0000, Wiles, Keith wrote: > > > > 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.
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
