From: Phillip Wood Date: Wed, 29 Jul 2020 09:12:59 GMT Subject: Re: [PATCH v2] fetch: optionally allow disabling FETCH_HEAD update Message-ID: In-Reply-To: On 28/07/2020 17:37, Junio C Hamano wrote: > Derrick Stolee writes: > >> On 7/27/2020 12:13 PM, Junio C Hamano wrote: >>> Derrick Stolee writes: >>> >>>> I'll rebase onto jc/no-update-fetch-head for the next version, since >>>> that branch is based on v2.28.0-rc0, which is recent enough. >>> >>> I do not think it is wise to base a work on top of unfinished "you >>> could do it this way, perhaps?" demonstration patch the original >>> author does not have much inclination to finish, though. >>> >>> When I am really bored, I may go back to the topic to finish it, but >>> I wouldn't mind if you took ownership of it at all. >> >> Ah. I didn't understand the status of that branch. I'll pull it in >> to this topic. > > So here is with one of the two things that I found missing in the > first iteration of the patch: documentation. > > The other thing that I found iffy (and still missing from this > version) was what should be done when "git pull" is explicitly given > the "--no-write-fetch-head" option. > > I think (but didn't check the recent code) that 'git pull' would > pass only known-to-make-sense command line options to underlying > 'git fetch', so it probably will barf with "unknown option", which > is the best case. We might want to make it sure with a new test in > 5521. On the other hand, if we get anything other than "no such > option", we may want to think if we want to "fix" it or just leave > it inside "if it hurts, don't do it" territory. > > Thanks. > > The patch without doc was Reviewed-by: Taylor Blau > but this round has not been. > > -- >8 -- > > If you run fetch but record the result in remote-tracking branches, > and either if you do nothing with the fetched refs (e.g. you are > merely mirroring) or if you always work from the remote-tracking > refs (e.g. you fetch and then merge origin/branchname separately), > you can get away with having no FETCH_HEAD at all. > > Teach "git fetch" a command line option "--[no-]write-fetch-head" > and "fetch.writeFetchHEAD" configuration variable. Without either, > the default is to write FETCH_HEAD, and the usual rule that the > command line option defeats configured default applies. > > Note that under "--dry-run" mode, FETCH_HEAD is never written; > otherwise you'd see list of objects in the file that you do not > actually have. Passing `--fetch-write-head` Typo, it should be `--write-fetch-head` >does not force `git > fetch` to write the file. > > Also note that this option is explicitly passed when "git pull" > internally invokes "git fetch", so that those who configured their > "git fetch" not to write FETCH_HEAD would not be able to break the > cooperation between these two commands. "git pull" must see what > "git fetch" got recorded in FETCH_HEAD to work correctly. > > Signed-off-by: Junio C Hamano > --- > Documentation/config/fetch.txt | 7 ++++++ > Documentation/fetch-options.txt | 10 +++++++++ > builtin/fetch.c | 19 +++++++++++++--- > builtin/pull.c | 3 ++- > t/t5510-fetch.sh | 39 +++++++++++++++++++++++++++++++-- > 5 files changed, 72 insertions(+), 6 deletions(-) > > diff --git a/Documentation/config/fetch.txt b/Documentation/config/fetch.txt > index b20394038d..0aaa05e8c0 100644 > --- a/Documentation/config/fetch.txt > +++ b/Documentation/config/fetch.txt > @@ -91,3 +91,10 @@ fetch.writeCommitGraph:: > merge and the write may take longer. Having an updated commit-graph > file helps performance of many Git commands, including `git merge-base`, > `git push -f`, and `git log --graph`. Defaults to false. > + > +fetch.writeFetchHEAD:: > + Setting it to false tells `git fetch` not to write the list > + of remote refs fetched in the `FETCH_HEAD` file directly > + under `$GIT_DIR`. Can be countermanded from the command > + line with the `--[no-]write-fetch-head` option. Defaults to > + true. > diff --git a/Documentation/fetch-options.txt b/Documentation/fetch-options.txt > index 6e2a160a47..6775e8499f 100644 > --- a/Documentation/fetch-options.txt > +++ b/Documentation/fetch-options.txt > @@ -64,6 +64,16 @@ documented in linkgit:git-config[1]. > --dry-run:: > Show what would be done, without making any changes. > > +ifndef::git-pull[] > +--[no-]write-fetch-head:: > + Write the list of remote refs fetched in the `FETCH_HEAD` > + file directly under `$GIT_DIR`. This is the default unless > + the configuration variable `fetch.writeFetchHEAD` is set to > + false. Passing `--no-write-fetch-head` from the command > + line tells Git not to write the file. Under `--dry-run` > + option, the file is never written. > +endif::git-pull[] > + > -f:: > --force:: > When 'git fetch' is used with `:` refspec it may > diff --git a/builtin/fetch.c b/builtin/fetch.c > index 82ac4be8a5..3ccf69753f 100644 > --- a/builtin/fetch.c > +++ b/builtin/fetch.c > @@ -56,6 +56,7 @@ static int prune_tags = -1; /* unspecified */ > #define PRUNE_TAGS_BY_DEFAULT 0 /* do we prune tags by default? */ > > static int all, append, dry_run, force, keep, multiple, update_head_ok; > +static int write_fetch_head = 1; > static int verbosity, deepen_relative, set_upstream; > static int progress = -1; > static int enable_auto_gc = 1; > @@ -118,6 +119,10 @@ static int git_fetch_config(const char *k, const char *v, void *cb) > return 0; > } > > + if (!strcmp(k, "fetch.writefetchhead")) { > + write_fetch_head = git_config_bool(k, v); > + return 0; > + } > return git_default_config(k, v, cb); > } > > @@ -162,6 +167,8 @@ static struct option builtin_fetch_options[] = { > PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules), > OPT_BOOL(0, "dry-run", &dry_run, > N_("dry run")), > + OPT_BOOL(0, "write-fetch-head", &write_fetch_head, > + N_("write fetched references to the FETCH_HEAD file")), > OPT_BOOL('k', "keep", &keep, N_("keep downloaded pack")), > OPT_BOOL('u', "update-head-ok", &update_head_ok, > N_("allow updating of HEAD ref")), > @@ -893,7 +900,9 @@ static int store_updated_refs(const char *raw_url, const char *remote_name, > const char *what, *kind; > struct ref *rm; > char *url; > - const char *filename = dry_run ? "/dev/null" : git_path_fetch_head(the_repository); > + const char *filename = (!write_fetch_head > + ? "/dev/null" > + : git_path_fetch_head(the_repository)); I was suspicious of this as we haven't cleared write_fetch_head in the --dry-run case yet but the test below seems to show that we still don't write FETCH_HEAD if --dry-run is given. That makes we wonder what the point of setting the filename based on the value of write_fetch_head is. The rest looks good to me, though it might be worth having a test to check that pull does indeed reject --no-write-fetch-head Best Wishes Phillip > int want_status; > int summary_width = transport_summary_width(ref_map); > > @@ -1327,7 +1336,7 @@ static int do_fetch(struct transport *transport, > } > > /* if not appending, truncate FETCH_HEAD */ > - if (!append && !dry_run) { > + if (!append && write_fetch_head) { > retcode = truncate_fetch_head(); > if (retcode) > goto cleanup; > @@ -1594,7 +1603,7 @@ static int fetch_multiple(struct string_list *list, int max_children) > int i, result = 0; > struct argv_array argv = ARGV_ARRAY_INIT; > > - if (!append && !dry_run) { > + if (!append && write_fetch_head) { > int errcode = truncate_fetch_head(); > if (errcode) > return errcode; > @@ -1795,6 +1804,10 @@ int cmd_fetch(int argc, const char **argv, const char *prefix) > if (depth || deepen_since || deepen_not.nr) > deepen = 1; > > + /* FETCH_HEAD never gets updated in --dry-run mode */ > + if (dry_run) > + write_fetch_head = 0; > + > if (all) { > if (argc == 1) > die(_("fetch --all does not take a repository argument")); > diff --git a/builtin/pull.c b/builtin/pull.c > index 8159c5d7c9..e988d92b53 100644 > --- a/builtin/pull.c > +++ b/builtin/pull.c > @@ -527,7 +527,8 @@ static int run_fetch(const char *repo, const char **refspecs) > struct argv_array args = ARGV_ARRAY_INIT; > int ret; > > - argv_array_pushl(&args, "fetch", "--update-head-ok", NULL); > + argv_array_pushl(&args, "fetch", "--update-head-ok", > + "--write-fetch-head", NULL); > > /* Shared options */ > argv_push_verbosity(&args); > diff --git a/t/t5510-fetch.sh b/t/t5510-fetch.sh > index a66dbe0bde..3052c2d8d5 100755 > --- a/t/t5510-fetch.sh > +++ b/t/t5510-fetch.sh > @@ -539,13 +539,48 @@ test_expect_success 'fetch into the current branch with --update-head-ok' ' > > ' > > -test_expect_success 'fetch --dry-run' ' > - > +test_expect_success 'fetch --dry-run does not touch FETCH_HEAD' ' > rm -f .git/FETCH_HEAD && > git fetch --dry-run . && > ! test -f .git/FETCH_HEAD > ' > > +test_expect_success '--no-write-fetch-head does not touch FETCH_HEAD' ' > + rm -f .git/FETCH_HEAD && > + git fetch --no-write-fetch-head . && > + ! test -f .git/FETCH_HEAD > +' > + > +test_expect_success '--write-fetch-head gets defeated by --dry-run' ' > + rm -f .git/FETCH_HEAD && > + git fetch --dry-run --write-fetch-head . && > + ! test -f .git/FETCH_HEAD > +' > + > +test_expect_success 'fetch.writeFetchHEAD and FETCH_HEAD' ' > + rm -f .git/FETCH_HEAD && > + git -c fetch.writeFetchHEAD=no fetch . && > + ! test -f .git/FETCH_HEAD > +' > + > +test_expect_success 'fetch.writeFetchHEAD gets defeated by --dry-run' ' > + rm -f .git/FETCH_HEAD && > + git -c fetch.writeFetchHEAD=yes fetch --dry-run . && > + ! test -f .git/FETCH_HEAD > +' > + > +test_expect_success 'fetch.writeFetchHEAD and --no-write-fetch-head' ' > + rm -f .git/FETCH_HEAD && > + git -c fetch.writeFetchHEAD=yes fetch --no-write-fetch-head . && > + ! test -f .git/FETCH_HEAD > +' > + > +test_expect_success 'fetch.writeFetchHEAD and --write-fetch-head' ' > + rm -f .git/FETCH_HEAD && > + git -c fetch.writeFetchHEAD=no fetch --write-fetch-head . && > + test -f .git/FETCH_HEAD > +' > + > test_expect_success "should be able to fetch with duplicate refspecs" ' > mkdir dups && > ( >