On Fri, Apr 16, 2021 at 12:49:57PM +0000, Derrick Stolee via GitGitGadget wrote:
> From: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
>
> The --prefetch option will be used by the 'prefetch' maintenance task
> instead of sending refspecs explicitly across the command-line. The
> intention is to modify the refspec to place all results in
> refs/prefetch/ instead of anywhere else.
>
> Create helper method filter_prefetch_refspec() to modify a given refspec
> to fit the rules expected of the prefetch task:
>
> * Negative refspecs are preserved.
> * Refspecs without a destination are removed.
> * Refspecs whose source starts with "refs/tags/" are removed.
> * Other refspecs are placed within "refs/prefetch/".
>
> Finally, we add the 'force' option to ensure that prefetch refs are
> replaced as necessary.
>
> There are some interesting cases that are worth testing.
>
> An earlier version of this change dropped the "i--" from the loop that
> deletes a refspec item and shifts the remaining entries down. This
> allowed some refspecs to not be modified. The subtle part about the
> first --prefetch test is that the "refs/tags/*" refspec appears directly
> before the "refs/heads/bogus/*" refspec. Without that "i--", this
> ordering would remove the "refs/tags/*" refspec and leave the last one
> unmodified, placing the result in "refs/heads/*".
>
> It is possible to have an empty refspec. This is typically the case for
> remotes other than the origin, where users want to fetch a specific tag
> or branch. To correctly test this case, we need to further remove the
> upstream remote for the local branch. Thus, we are testing a refspec
> that will be deleted, leaving nothing to fetch.
>
> Helped-by: Tom Saeger <tom.saeger@xxxxxxxxxx>
> Helped-by: Ramsay Jones <ramsay@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
> ---
> Documentation/fetch-options.txt | 5 +++
> builtin/fetch.c | 59 ++++++++++++++++++++++++++++++-
> t/t5582-fetch-negative-refspec.sh | 43 ++++++++++++++++++++++
> 3 files changed, 106 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/fetch-options.txt b/Documentation/fetch-options.txt
> index 07783deee309..9e7b4e189ce0 100644
> --- a/Documentation/fetch-options.txt
> +++ b/Documentation/fetch-options.txt
> @@ -110,6 +110,11 @@ ifndef::git-pull[]
> setting `fetch.writeCommitGraph`.
> endif::git-pull[]
>
> +--prefetch::
> + Modify the configured refspec to place all refs into the
> + `refs/prefetch/` namespace. See the `prefetch` task in
> + linkgit:git-maintenance[1].
> +
> -p::
> --prune::
> Before fetching, remove any remote-tracking references that no
> diff --git a/builtin/fetch.c b/builtin/fetch.c
> index 0b90de87c7a2..97c4fe6e6d66 100644
> --- a/builtin/fetch.c
> +++ b/builtin/fetch.c
> @@ -48,6 +48,7 @@ enum {
> static int fetch_prune_config = -1; /* unspecified */
> static int fetch_show_forced_updates = 1;
> static uint64_t forced_updates_ms = 0;
> +static int prefetch = 0;
> static int prune = -1; /* unspecified */
> #define PRUNE_BY_DEFAULT 0 /* do we prune by default? */
>
> @@ -158,6 +159,8 @@ static struct option builtin_fetch_options[] = {
> N_("do not fetch all tags (--no-tags)"), TAGS_UNSET),
> OPT_INTEGER('j', "jobs", &max_jobs,
> N_("number of submodules fetched in parallel")),
> + OPT_BOOL(0, "prefetch", &prefetch,
> + N_("modify the refspec to place all refs within refs/prefetch/")),
> OPT_BOOL('p', "prune", &prune,
> N_("prune remote-tracking branches no longer on remote")),
> OPT_BOOL('P', "prune-tags", &prune_tags,
> @@ -436,6 +439,56 @@ static void find_non_local_tags(const struct ref *refs,
> oidset_clear(&fetch_oids);
> }
>
> +static void filter_prefetch_refspec(struct refspec *rs)
> +{
> + int i;
> +
> + if (!prefetch)
> + return;
> +
> + for (i = 0; i < rs->nr; i++) {
> + struct strbuf new_dst = STRBUF_INIT;
> + char *old_dst;
> + const char *sub = NULL;
> +
> + if (rs->items[i].negative)
> + continue;
> + if (!rs->items[i].dst ||
> + (rs->items[i].src &&
> + !strncmp(rs->items[i].src, "refs/tags/", 10))) {
> + int j;
> +
> + free(rs->items[i].src);
> + free(rs->items[i].dst);
> +
> + for (j = i + 1; j < rs->nr; j++) {
> + rs->items[j - 1] = rs->items[j];
> + rs->raw[j - 1] = rs->raw[j];
> + }
> + rs->nr--;
> + i--;
> + continue;
> + }
> +
> + old_dst = rs->items[i].dst;
> + strbuf_addstr(&new_dst, "refs/prefetch/");
> +
> + /*
> + * If old_dst starts with "refs/", then place
> + * sub after that prefix. Otherwise, start at
> + * the beginning of the string.
> + */
> + if (!skip_prefix(old_dst, "refs/", &sub))
> + sub = old_dst;
> + strbuf_addstr(&new_dst, sub);
> +
> + rs->items[i].dst = strbuf_detach(&new_dst, NULL);
> + rs->items[i].force = 1;
> +
> + free(old_dst);
> + }
> +}
> +
> static struct ref *get_ref_map(struct remote *remote,
> const struct ref *remote_refs,
> struct refspec *rs,
> @@ -452,6 +505,10 @@ static struct ref *get_ref_map(struct remote *remote,
> struct hashmap existing_refs;
> int existing_refs_populated = 0;
>
> + filter_prefetch_refspec(rs);
> + if (remote)
> + filter_prefetch_refspec(&remote->fetch);
> +
> if (rs->nr) {
> struct refspec *fetch_refspec;
>
> @@ -520,7 +577,7 @@ static struct ref *get_ref_map(struct remote *remote,
> if (has_merge &&
> !strcmp(branch->remote_name, remote->name))
> add_merge_config(&ref_map, remote_refs, branch, &tail);
> - } else {
> + } else if (!prefetch) {
That works for me.
> ref_map = get_remote_ref(remote_refs, "HEAD");
> if (!ref_map)
> die(_("Couldn't find remote ref HEAD"));
> diff --git a/t/t5582-fetch-negative-refspec.sh b/t/t5582-fetch-negative-refspec.sh
> index f34509727702..e5d2e79ad382 100755
> --- a/t/t5582-fetch-negative-refspec.sh
> +++ b/t/t5582-fetch-negative-refspec.sh
> @@ -240,4 +240,47 @@ test_expect_success "push with matching +: and negative refspec" '
> git -C two push -v one
> '
>
> +test_expect_success '--prefetch correctly modifies refspecs' '
> + git -C one config --unset-all remote.origin.fetch &&
> + git -C one config --add remote.origin.fetch ^refs/heads/bogus/ignore &&
> + git -C one config --add remote.origin.fetch "refs/tags/*:refs/tags/*" &&
> + git -C one config --add remote.origin.fetch "refs/heads/bogus/*:bogus/*" &&
> +
> + git tag -a -m never never-fetch-tag HEAD &&
> +
> + git branch bogus/fetched HEAD~1 &&
> + git branch bogus/ignore HEAD &&
> +
> + git -C one fetch --prefetch --no-tags &&
> + test_must_fail git -C one rev-parse never-fetch-tag &&
> + git -C one rev-parse refs/prefetch/bogus/fetched &&
> + test_must_fail git -C one rev-parse refs/prefetch/bogus/ignore &&
> +
> + # correctly handle when refspec set becomes empty
> + # after removing the refs/tags/* refspec.
> + git -C one config --unset-all remote.origin.fetch &&
> + git -C one config --add remote.origin.fetch "refs/tags/*:refs/tags/*" &&
> +
> + git -C one fetch --prefetch --no-tags &&
> + test_must_fail git -C one rev-parse never-fetch-tag &&
> +
> + # The refspec for refs that are not fully qualified
> + # are filtered multiple times.
> + git -C one rev-parse refs/prefetch/bogus/fetched &&
> + test_must_fail git -C one rev-parse refs/prefetch/bogus/ignore
> +'
> +
> +test_expect_success '--prefetch succeeds when refspec becomes empty' '
technically this will get skipped based only on "skipfetchall" right?
The remote could have an empty-set of refspecs or multiple
valid refspecs post filter_prefetch_refspec, but the remote gets skipped altogether.
perhaps '--prefetch succeeds when remote.skipfetchall is true' '
anyway this is looking pretty solid
Reviewed-by: Tom Saeger <tom.saeger@xxxxxxxxxx>
> + git checkout bogus/fetched &&
> + test_commit extra &&
> +
> + git -C one config --unset-all remote.origin.fetch &&
> + git -C one config --unset branch.main.remote &&
> + git -C one config remote.origin.fetch "+refs/tags/extra" &&
> + git -C one config remote.origin.skipfetchall true &&
> + git -C one config remote.origin.tagopt "--no-tags" &&
> +
> + git -C one fetch --prefetch
> +'
> +
> test_done
> --
> gitgitgadget
>
