From: Jeff Hostetler Date: Thu, 28 Sep 2017 14:33:39 GMT Subject: Re: [PATCH 07/13] object-filter: common declarations for object filtering Message-ID: <3cab0259-f20e-5913-d886-e37c4da9fd04@jeffhostetler.com> In-Reply-To: <20170927170533.65498396e008fa148a3fda90@google.com> On 9/27/2017 8:05 PM, Jonathan Tan wrote: > On Wed, 27 Sep 2017 13:09:42 -0400 > Jeff Hostetler wrote: > >> On 9/26/2017 6:39 PM, Jonathan Tan wrote: >>> On Fri, 22 Sep 2017 20:30:11 +0000 >>> Jeff Hostetler wrote: >>> >>>> Makefile | 1 + >>>> object-filter.c | 269 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >>>> object-filter.h | 173 ++++++++++++++++++++++++++++++++++++ >>>> 3 files changed, 443 insertions(+) >>>> create mode 100644 object-filter.c >>>> create mode 100644 object-filter.h >>> >>> I think these and list-objects-filter-* are multiple levels of >>> indirection too many. Would a single file with a few implementations of >>> filter_object_fn be sufficient? >> >> I did that in my first draft and I found it confusing. >> >> Each filter has 3 parts (some filter-specific data structures, >> a filter callback routine, a driver to call the traverse code). >> I found it easier to reason about each filter in isolation. >> And it makes it easier to work on each independently and keep >> their inclusion in separate commits. > > I looked at object-filter.{c,h} a bit more. It seems that these files: > 1) define a struct that contains all the options that we would want > 2) supplies a way to populate this struct from code that uses parse-options > 3) supplies a way to populate this struct from code that calculates > options by hand > 4) supplies a way to populate this struct from "protocol" ("" or > " " strings) > > And the next commit takes the struct that object-filter.{c,h} produces > and actually performs the traversal. > > I think this can be significantly simplified, though. Would this work: > a) Define the object_filter_options struct, but make all fields > correspond to a single parameter each. Define > OBJECT_FILTER_OPTIONS_INIT to initialize everything to 0 except for > large_byte_limit to ULONG_MAX (so that we can detect if something > else is set to it). > b) Define one single OPT_PARSE_FILTER macro containing all the > parameters. We can use the non-callback macros here. That solves 2) > above. > c) Define a function that takes in (int *argc, char ***argv) that can > "massage" it to remove all filter-related arguments, storing them in > a object_filter_options struct. That solves 3) above. As discussed > in the API documentation, this means that argument lists of the form > "--unknown --known" (where "--unknown" takes an argument) are > processed differently, but then again, rev-list never supported them > anyway (it required "--unknown="). > d) Define a function that converts "" into "--" and " > " into "--=", and use the existing mechanism. > That solves 4) above. > > This removes the need to maintain the lists of one-per-argument > functions, including the parse_filter_* and opt_parse_filter_* functions > declared in the header file. If we were to add a feature, we wouldn't > need to change anything in the caller, and wouldn't need to hand-edit > object_filter_hand_parse_arg() and object_filter_hand_parse_protocol(). Maybe. What I have here now is the result of adding these arguments to rev-list and pack-objects (in the current patch series), and also to fetch-pack, fetch, clone, upload-pack, index-pack, and the transport and protocol code (in a follow-on patch series that I've omitted for the moment). And there will probably be a few more, such as fsck, gc, and etc. I hesitate to refine the macros too much further until we've agreement on the overall approach and terms. Thanks Jeff