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diff: batch fetching of missing blobs 

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>
maint
Jonathan Tan 2019-04-05 10:09:34 -07:00 committed by Junio C Hamano
parent 0f4a4fb1c4
commit 7fbbcb21b1
2 changed files with 137 additions and 0 deletions
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34
diff.c
View File

@ -25,6 +25,7 @@
#include "packfile.h"
#include "parse-options.h"
#include "help.h"
#include "fetch-object.h"

#ifdef NO_FAST_WORKING_DIRECTORY
#define FAST_WORKING_DIRECTORY 0
@ -6366,8 +6367,41 @@ void diffcore_fix_diff_index(void)
QSORT(q->queue, q->nr, diffnamecmp);
}

static void add_if_missing(struct repository *r,
struct oid_array *to_fetch,
const struct diff_filespec *filespec)
{
if (filespec && filespec->oid_valid &&
oid_object_info_extended(r, &filespec->oid, NULL,
OBJECT_INFO_FOR_PREFETCH))
oid_array_append(to_fetch, &filespec->oid);
}

void diffcore_std(struct diff_options *options)
{
if (options->repo == the_repository &&
repository_format_partial_clone) {
/*
* Prefetch the diff pairs that are about to be flushed.
*/
int i;
struct diff_queue_struct *q = &diff_queued_diff;
struct oid_array to_fetch = OID_ARRAY_INIT;

for (i = 0; i < q->nr; i++) {
struct diff_filepair *p = q->queue[i];
add_if_missing(options->repo, &to_fetch, p->one);
add_if_missing(options->repo, &to_fetch, p->two);
}
if (to_fetch.nr)
/*
* NEEDSWORK: Consider deduplicating the OIDs sent.
*/
fetch_objects(repository_format_partial_clone,
to_fetch.oid, to_fetch.nr);
oid_array_clear(&to_fetch);
}

/* NOTE please keep the following in sync with diff_tree_combined() */
if (options->skip_stat_unmatch)
diffcore_skip_stat_unmatch(options);

103
t/t4067-diff-partial-clone.sh Executable file
View File

@ -0,0 +1,103 @@
#!/bin/sh

test_description='behavior of diff when reading objects in a partial clone'

. ./test-lib.sh

test_expect_success 'git show batches blobs' '
test_when_finished "rm -rf server client trace" &&

test_create_repo server &&
echo a >server/a &&
echo b >server/b &&
git -C server add a b &&
git -C server commit -m x &&

test_config -C server uploadpack.allowfilter 1 &&
test_config -C server uploadpack.allowanysha1inwant 1 &&
git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&

# Ensure that there is exactly 1 negotiation by checking that there is
# only 1 "done" line sent. ("done" marks the end of negotiation.)
GIT_TRACE_PACKET="$(pwd)/trace" git -C client show HEAD &&
grep "git> done" trace >done_lines &&
test_line_count = 1 done_lines
'

test_expect_success 'diff batches blobs' '
test_when_finished "rm -rf server client trace" &&

test_create_repo server &&
echo a >server/a &&
echo b >server/b &&
git -C server add a b &&
git -C server commit -m x &&
echo c >server/c &&
echo d >server/d &&
git -C server add c d &&
git -C server commit -m x &&

test_config -C server uploadpack.allowfilter 1 &&
test_config -C server uploadpack.allowanysha1inwant 1 &&
git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&

# Ensure that there is exactly 1 negotiation by checking that there is
# only 1 "done" line sent. ("done" marks the end of negotiation.)
GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff HEAD^ HEAD &&
grep "git> done" trace >done_lines &&
test_line_count = 1 done_lines
'

test_expect_success 'diff skips same-OID blobs' '
test_when_finished "rm -rf server client trace" &&

test_create_repo server &&
echo a >server/a &&
echo b >server/b &&
git -C server add a b &&
git -C server commit -m x &&
echo another-a >server/a &&
git -C server add a &&
git -C server commit -m x &&

test_config -C server uploadpack.allowfilter 1 &&
test_config -C server uploadpack.allowanysha1inwant 1 &&
git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&

echo a | git hash-object --stdin >hash-old-a &&
echo another-a | git hash-object --stdin >hash-new-a &&
echo b | git hash-object --stdin >hash-b &&

# Ensure that only a and another-a are fetched.
GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff HEAD^ HEAD &&
grep "want $(cat hash-old-a)" trace &&
grep "want $(cat hash-new-a)" trace &&
! grep "want $(cat hash-b)" trace
'

test_expect_success 'diff with rename detection batches blobs' '
test_when_finished "rm -rf server client trace" &&

test_create_repo server &&
echo a >server/a &&
printf "b\nb\nb\nb\nb\n" >server/b &&
git -C server add a b &&
git -C server commit -m x &&
rm server/b &&
printf "b\nb\nb\nb\nbX\n" >server/c &&
git -C server add c &&
git -C server commit -a -m x &&

test_config -C server uploadpack.allowfilter 1 &&
test_config -C server uploadpack.allowanysha1inwant 1 &&
git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&

# Ensure that there is exactly 1 negotiation by checking that there is
# only 1 "done" line sent. ("done" marks the end of negotiation.)
GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff -M HEAD^ HEAD >out &&
grep "similarity index" out &&
grep "git> done" trace >done_lines &&
test_line_count = 1 done_lines
'

test_done