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@xxxxxxxx>
Signed-off-by: Jonathan Tan <jonathantanmy@xxxxxxxxxx>
---
diff.c | 73 ++++++++++++++++++++++++-----------
diffcore-break.c | 12 +++++-
diffcore-rename.c | 55 ++++++++++++++++++++++++--
diffcore.h | 21 ++++++++++
t/t4067-diff-partial-clone.sh | 48 +++++++++++++++++++++++
5 files changed, 181 insertions(+), 28 deletions(-)
diff --git a/diff.c b/diff.c
index 8db981b906..d1ad6a3c4a 100644
--- a/diff.c
+++ b/diff.c
@@ -4034,10 +4034,18 @@ int diff_populate_filespec(struct repository *r,
*/
info.contentp = &s->data;
+ if (options && options->missing_object_cb) {
+ if (!oid_object_info_extended(r, &s->oid, &info,
+ OBJECT_INFO_LOOKUP_REPLACE |
+ OBJECT_INFO_SKIP_FETCH_OBJECT))
+ goto object_read;
+ options->missing_object_cb(options->missing_object_data);
+ }
if (oid_object_info_extended(r, &s->oid, &info,
OBJECT_INFO_LOOKUP_REPLACE))
die("unable to read %s", oid_to_hex(&s->oid));
+object_read:
if (size_only || check_binary) {
if (size_only)
return 0;
@@ -6447,6 +6455,8 @@ static int diff_filespec_check_stat_unmatch(struct repository *r,
{
struct diff_populate_filespec_options dpf_options = {
.check_size_only = 1,
+ .missing_object_cb = diff_queued_diff_prefetch,
+ .missing_object_data = r,
};
if (p->done_skip_stat_unmatch)
@@ -6523,9 +6533,9 @@ 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)
+void diff_add_if_missing(struct repository *r,
+ struct oid_array *to_fetch,
+ const struct diff_filespec *filespec)
{
if (filespec && filespec->oid_valid &&
!S_ISGITLINK(filespec->mode) &&
@@ -6534,29 +6544,48 @@ static void add_if_missing(struct repository *r,
oid_array_append(to_fetch, &filespec->oid);
}
-void diffcore_std(struct diff_options *options)
+void diff_queued_diff_prefetch(void *repository)
{
- if (options->repo == the_repository && has_promisor_remote()) {
- /*
- * 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;
+ struct repository *repo = repository;
+ 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);
- }
- /*
- * NEEDSWORK: Consider deduplicating the OIDs sent.
- */
- promisor_remote_get_direct(options->repo,
- to_fetch.oid, to_fetch.nr);
- oid_array_clear(&to_fetch);
+ for (i = 0; i < q->nr; i++) {
+ struct diff_filepair *p = q->queue[i];
+ diff_add_if_missing(repo, &to_fetch, p->one);
+ diff_add_if_missing(repo, &to_fetch, p->two);
}
+ /*
+ * NEEDSWORK: Consider deduplicating the OIDs sent.
+ */
+ promisor_remote_get_direct(repo, to_fetch.oid, to_fetch.nr);
+
+ oid_array_clear(&to_fetch);
+}
+
+void diffcore_std(struct diff_options *options)
+{
+ int output_formats_to_prefetch = DIFF_FORMAT_DIFFSTAT |
+ DIFF_FORMAT_NUMSTAT |
+ DIFF_FORMAT_PATCH |
+ DIFF_FORMAT_SHORTSTAT |
+ DIFF_FORMAT_DIRSTAT;
+
+ /*
+ * Check if the user requested a blob-data-requiring diff output and/or
+ * break-rewrite detection (which requires blob data). If yes, prefetch
+ * the diff pairs.
+ *
+ * If no prefetching occurs, diffcore_rename() will prefetch if it
+ * decides that it needs inexact rename detection.
+ */
+ if (options->repo == the_repository && has_promisor_remote() &&
+ (options->output_format & output_formats_to_prefetch ||
+ options->pickaxe_opts & DIFF_PICKAXE_KINDS_MASK))
+ diff_queued_diff_prefetch(options->repo);
+
/* NOTE please keep the following in sync with diff_tree_combined() */
if (options->skip_stat_unmatch)
diffcore_skip_stat_unmatch(options);
diff --git a/diffcore-break.c b/diffcore-break.c
index e8f6322c6a..0d4a14964d 100644
--- a/diffcore-break.c
+++ b/diffcore-break.c
@@ -4,6 +4,7 @@
#include "cache.h"
#include "diff.h"
#include "diffcore.h"
+#include "promisor-remote.h"
static int should_break(struct repository *r,
struct diff_filespec *src,
@@ -49,6 +50,8 @@ static int should_break(struct repository *r,
unsigned long delta_size, max_size;
unsigned long src_copied, literal_added, src_removed;
+ struct diff_populate_filespec_options options = { 0 };
+
*merge_score_p = 0; /* assume no deletion --- "do not break"
* is the default.
*/
@@ -62,8 +65,13 @@ static int should_break(struct repository *r,
oideq(&src->oid, &dst->oid))
return 0; /* they are the same */
- if (diff_populate_filespec(r, src, NULL) ||
- diff_populate_filespec(r, dst, NULL))
+ if (r == the_repository && has_promisor_remote()) {
+ options.missing_object_cb = diff_queued_diff_prefetch;
+ options.missing_object_data = r;
+ }
+
+ if (diff_populate_filespec(r, src, &options) ||
+ diff_populate_filespec(r, dst, &options))
return 0; /* error but caught downstream */
max_size = ((src->size > dst->size) ? src->size : dst->size);
diff --git a/diffcore-rename.c b/diffcore-rename.c
index bf4c0b8740..99e63e90f8 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -1,4 +1,5 @@
/*
+ *
* Copyright (C) 2005 Junio C Hamano
*/
#include "cache.h"
@@ -7,6 +8,7 @@
#include "object-store.h"
#include "hashmap.h"
#include "progress.h"
+#include "promisor-remote.h"
/* Table of rename/copy destinations */
@@ -128,10 +130,46 @@ struct diff_score {
short name_score;
};
+struct prefetch_options {
+ struct repository *repo;
+ int skip_unmodified;
+};
+static void prefetch(void *prefetch_options)
+{
+ struct prefetch_options *options = prefetch_options;
+ int i;
+ struct oid_array to_fetch = OID_ARRAY_INIT;
+
+ for (i = 0; i < rename_dst_nr; i++) {
+ if (rename_dst[i].pair)
+ /*
+ * The loop in diffcore_rename() will not need these
+ * blobs, so skip prefetching.
+ */
+ continue; /* already found exact match */
+ diff_add_if_missing(options->repo, &to_fetch,
+ rename_dst[i].two);
+ }
+ for (i = 0; i < rename_src_nr; i++) {
+ if (options->skip_unmodified &&
+ diff_unmodified_pair(rename_src[i].p))
+ /*
+ * The loop in diffcore_rename() will not need these
+ * blobs, so skip prefetching.
+ */
+ continue;
+ diff_add_if_missing(options->repo, &to_fetch,
+ rename_src[i].p->one);
+ }
+ promisor_remote_get_direct(options->repo, to_fetch.oid, to_fetch.nr);
+ oid_array_clear(&to_fetch);
+}
+
static int estimate_similarity(struct repository *r,
struct diff_filespec *src,
struct diff_filespec *dst,
- int minimum_score)
+ int minimum_score,
+ int skip_unmodified)
{
/* src points at a file that existed in the original tree (or
* optionally a file in the destination tree) and dst points
@@ -151,6 +189,12 @@ static int estimate_similarity(struct repository *r,
struct diff_populate_filespec_options dpf_options = {
.check_size_only = 1
};
+ struct prefetch_options prefetch_options = {r, skip_unmodified};
+
+ if (r == the_repository && has_promisor_remote()) {
+ dpf_options.missing_object_cb = prefetch;
+ dpf_options.missing_object_data = &prefetch_options;
+ }
/* We deal only with regular files. Symlink renames are handled
* only when they are exact matches --- in other words, no edits
@@ -190,9 +234,11 @@ static int estimate_similarity(struct repository *r,
if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
return 0;
- if (!src->cnt_data && diff_populate_filespec(r, src, NULL))
+ dpf_options.check_size_only = 0;
+
+ if (!src->cnt_data && diff_populate_filespec(r, src, &dpf_options))
return 0;
- if (!dst->cnt_data && diff_populate_filespec(r, dst, NULL))
+ if (!dst->cnt_data && diff_populate_filespec(r, dst, &dpf_options))
return 0;
if (diffcore_count_changes(r, src, dst,
@@ -569,7 +615,8 @@ void diffcore_rename(struct diff_options *options)
this_src.score = estimate_similarity(options->repo,
one, two,
- minimum_score);
+ minimum_score,
+ skip_unmodified);
this_src.name_score = basename_same(one, two);
this_src.dst = i;
this_src.src = j;
diff --git a/diffcore.h b/diffcore.h
index 3b2020ce93..d2a63c5c71 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -65,9 +65,22 @@ void free_filespec(struct diff_filespec *);
void fill_filespec(struct diff_filespec *, const struct object_id *,
int, unsigned short);
+/*
+ * Prefetch the entries in diff_queued_diff. The parameter is a pointer to a
+ * struct repository.
+ */
+void diff_queued_diff_prefetch(void *repository);
+
struct diff_populate_filespec_options {
unsigned check_size_only : 1;
unsigned check_binary : 1;
+
+ /*
+ * If an object is missing, diff_populate_filespec() will invoke this
+ * callback before attempting to read that object again.
+ */
+ void (*missing_object_cb)(void *);
+ void *missing_object_data;
};
int diff_populate_filespec(struct repository *, struct diff_filespec *,
const struct diff_populate_filespec_options *);
@@ -185,4 +198,12 @@ int diffcore_count_changes(struct repository *r,
unsigned long *src_copied,
unsigned long *literal_added);
+/*
+ * If filespec contains an OID and if that object is missing from the given
+ * repository, add that OID to to_fetch.
+ */
+void diff_add_if_missing(struct repository *r,
+ struct oid_array *to_fetch,
+ const struct diff_filespec *filespec);
+
#endif
diff --git a/t/t4067-diff-partial-clone.sh b/t/t4067-diff-partial-clone.sh
index 4831ad35e6..c1ed1c2fc4 100755
--- a/t/t4067-diff-partial-clone.sh
+++ b/t/t4067-diff-partial-clone.sh
@@ -131,4 +131,52 @@ test_expect_success 'diff with rename detection batches blobs' '
test_line_count = 1 done_lines
'
+test_expect_success 'diff does not fetch anything if inexact rename detection is not needed' '
+ 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 &&
+ mv server/b 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://$(pwd)/server" client &&
+
+ # Ensure no fetches.
+ GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff --raw -M HEAD^ HEAD &&
+ ! test_path_exists trace
+'
+
+test_expect_success 'diff --break-rewrites fetches only if necessary, and batches blobs if it does' '
+ 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 &&
+ printf "c\nc\nc\nc\nc\n" >server/b &&
+ 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://$(pwd)/server" client &&
+
+ # Ensure no fetches.
+ GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff --raw -M HEAD^ HEAD &&
+ ! test_path_exists trace &&
+
+ # But with --break-rewrites, 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 --break-rewrites --raw -M HEAD^ HEAD &&
+ grep "git> done" trace >done_lines &&
+ test_line_count = 1 done_lines
+'
+
test_done
--
2.26.0.292.g33ef6b2f38-goog
