Teach Git to lazy-fetch missing objects in a subprocess instead of doing
it in-process. This allows any fatal errors that occur during the fetch
to be isolated and converted into an error return value, instead of
causing the current command being run to terminate.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
95acf11a3d ("diff: restrict when prefetching occurs", 2020-04-07) taught
diff to prefetch blobs in a more limited set of situations. These
limited situations include when the output format requires blob data,
and when inexact rename detection is needed.
There is an existing test case that tests inexact rename detection, but
it also uses an output format that requires blob data, resulting in the
inexact-rename-detection-only code not being tested. Update this test to
use the raw output format, which does not require blob data.
Thanks to Derrick Stolee for noticing this lapse in code coverage and
for doing the preliminary analysis [1].
[1] https://lore.kernel.org/git/853759d3-97c3-241f-98e1-990883cd204e@gmail.com/
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commit 7fbbcb21b1 ("diff: batch fetching of missing blobs", 2019-04-08)
optimized "diff" by prefetching blobs in a partial clone, but there are
some cases wherein blobs do not need to be prefetched. In these cases,
any command that uses the diff machinery will unnecessarily fetch blobs.
diffcore_std() may read blobs when it calls the following functions:
(1) diffcore_skip_stat_unmatch() (controlled by the config variable
diff.autorefreshindex)
(2) diffcore_break() and diffcore_merge_broken() (for break-rewrite
detection)
(3) diffcore_rename() (for rename detection)
(4) diffcore_pickaxe() (for detecting addition/deletion of specified
string)
Instead of always prefetching blobs, teach diffcore_skip_stat_unmatch(),
diffcore_break(), and diffcore_rename() to prefetch blobs upon the first
read of a missing object. This covers (1), (2), and (3): to cover the
rest, teach diffcore_std() to prefetch if the output type is one that
includes blob data (and hence blob data will be required later anyway),
or if it knows that (4) will be run.
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 7fbbcb21b1 ("diff: batch fetching of missing blobs", 2019-04-08),
diff was taught to batch the fetching of missing objects when operating
on a partial clone, but was not taught to refrain from fetching
GITLINKs. Teach diff to check if an object is a GITLINK before including
it in the set to be fetched.
(As stated in the commit message of that commit, unpack-trees was also
taught a similar thing prior, but unpack-trees correctly checks for
GITLINK before including objects in the set to be fetched.)
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When running a command like "git show" or "git diff" in a partial clone,
batch all missing blobs to be fetched as one request.
This is similar to c0c578b33c ("unpack-trees: batch fetching of missing
blobs", 2017-12-08), but for another command.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
