From: Abhradeep Chakraborty <chakrabortyabhradeep79@xxxxxxxxx>
Teach git to provide a way for users to enable/disable bitmap lookup
table extension by providing a config option named 'writeBitmapLookupTable'.
Default is true.
Also add test to verify writting of lookup table.
Co-Authored-by: Taylor Blau <me@xxxxxxxxxxxx>
Signed-off-by: Abhradeep Chakraborty <chakrabortyabhradeep79@xxxxxxxxx>
Mentored-by: Taylor Blau <me@xxxxxxxxxxxx>
Co-Mentored-by: Kaartic Sivaraam <kaartic.sivaraam@xxxxxxxxx>
---
Documentation/config/pack.txt | 7 +++++++
builtin/multi-pack-index.c | 8 ++++++++
builtin/pack-objects.c | 10 +++++++++-
midx.c | 3 +++
midx.h | 1 +
pack-bitmap-write.c | 2 ++
t/t5310-pack-bitmaps.sh | 3 ++-
t/t5326-multi-pack-bitmaps.sh | 13 +++++++++++++
8 files changed, 45 insertions(+), 2 deletions(-)
diff --git a/Documentation/config/pack.txt b/Documentation/config/pack.txt
index ad7f73a1ead..6e1f454c4d6 100644
--- a/Documentation/config/pack.txt
+++ b/Documentation/config/pack.txt
@@ -164,6 +164,13 @@ When writing a multi-pack reachability bitmap, no new namehashes are
computed; instead, any namehashes stored in an existing bitmap are
permuted into their appropriate location when writing a new bitmap.
+pack.writeBitmapLookupTable::
+ When true, git will include a "lookup table" section in the
+ bitmap index (if one is written). This table is used to defer
+ loading individual bitmaps as late as possible. This can be
+ beneficial in repositories which have relatively large bitmap
+ indexes. Defaults to true.
+
pack.writeReverseIndex::
When true, git will write a corresponding .rev file (see:
link:../technical/pack-format.html[Documentation/technical/pack-format.txt])
diff --git a/builtin/multi-pack-index.c b/builtin/multi-pack-index.c
index 5edbb7fe86e..3757616f09c 100644
--- a/builtin/multi-pack-index.c
+++ b/builtin/multi-pack-index.c
@@ -87,6 +87,13 @@ static int git_multi_pack_index_write_config(const char *var, const char *value,
opts.flags &= ~MIDX_WRITE_BITMAP_HASH_CACHE;
}
+ if (!strcmp(var, "pack.writebitmaplookuptable")) {
+ if (git_config_bool(var, value))
+ opts.flags |= MIDX_WRITE_BITMAP_LOOKUP_TABLE;
+ else
+ opts.flags &= ~MIDX_WRITE_BITMAP_LOOKUP_TABLE;
+ }
+
/*
* We should never make a fall-back call to 'git_default_config', since
* this was already called in 'cmd_multi_pack_index()'.
@@ -123,6 +130,7 @@ static int cmd_multi_pack_index_write(int argc, const char **argv)
};
opts.flags |= MIDX_WRITE_BITMAP_HASH_CACHE;
+ opts.flags |= MIDX_WRITE_BITMAP_LOOKUP_TABLE;
git_config(git_multi_pack_index_write_config, NULL);
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 39e28cfcafc..d6a33fd486c 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -228,7 +228,7 @@ static enum {
WRITE_BITMAP_QUIET,
WRITE_BITMAP_TRUE,
} write_bitmap_index;
-static uint16_t write_bitmap_options = BITMAP_OPT_HASH_CACHE;
+static uint16_t write_bitmap_options = BITMAP_OPT_HASH_CACHE | BITMAP_OPT_LOOKUP_TABLE;
static int exclude_promisor_objects;
@@ -3148,6 +3148,14 @@ static int git_pack_config(const char *k, const char *v, void *cb)
else
write_bitmap_options &= ~BITMAP_OPT_HASH_CACHE;
}
+
+ if (!strcmp(k, "pack.writebitmaplookuptable")) {
+ if (git_config_bool(k, v))
+ write_bitmap_options |= BITMAP_OPT_LOOKUP_TABLE;
+ else
+ write_bitmap_options &= ~BITMAP_OPT_LOOKUP_TABLE;
+ }
+
if (!strcmp(k, "pack.usebitmaps")) {
use_bitmap_index_default = git_config_bool(k, v);
return 0;
diff --git a/midx.c b/midx.c
index 5f0dd386b02..9c26d04bfde 100644
--- a/midx.c
+++ b/midx.c
@@ -1072,6 +1072,9 @@ static int write_midx_bitmap(char *midx_name, unsigned char *midx_hash,
if (flags & MIDX_WRITE_BITMAP_HASH_CACHE)
options |= BITMAP_OPT_HASH_CACHE;
+ if (flags & MIDX_WRITE_BITMAP_LOOKUP_TABLE)
+ options |= BITMAP_OPT_LOOKUP_TABLE;
+
prepare_midx_packing_data(&pdata, ctx);
commits = find_commits_for_midx_bitmap(&commits_nr, refs_snapshot, ctx);
diff --git a/midx.h b/midx.h
index 22e8e53288e..5578cd7b835 100644
--- a/midx.h
+++ b/midx.h
@@ -47,6 +47,7 @@ struct multi_pack_index {
#define MIDX_WRITE_REV_INDEX (1 << 1)
#define MIDX_WRITE_BITMAP (1 << 2)
#define MIDX_WRITE_BITMAP_HASH_CACHE (1 << 3)
+#define MIDX_WRITE_BITMAP_LOOKUP_TABLE (1 << 4)
const unsigned char *get_midx_checksum(struct multi_pack_index *m);
void get_midx_filename(struct strbuf *out, const char *object_dir);
diff --git a/pack-bitmap-write.c b/pack-bitmap-write.c
index 899a4a941e1..79be0cf80e6 100644
--- a/pack-bitmap-write.c
+++ b/pack-bitmap-write.c
@@ -713,6 +713,7 @@ static void write_lookup_table(struct hashfile *f,
for (i = 0; i < writer.selected_nr; i++)
table_inv[table[i]] = i;
+ trace2_region_enter("pack-bitmap-write", "writing_lookup_table", the_repository);
for (i = 0; i < writer.selected_nr; i++) {
struct bitmapped_commit *selected = &writer.selected[table[i]];
uint32_t xor_offset = selected->xor_offset;
@@ -725,6 +726,7 @@ static void write_lookup_table(struct hashfile *f,
free(table);
free(table_inv);
+ trace2_region_leave("pack-bitmap-write", "writing_lookup_table", the_repository);
}
static void write_hash_cache(struct hashfile *f,
diff --git a/t/t5310-pack-bitmaps.sh b/t/t5310-pack-bitmaps.sh
index f775fc1ce69..c669ed959e9 100755
--- a/t/t5310-pack-bitmaps.sh
+++ b/t/t5310-pack-bitmaps.sh
@@ -38,7 +38,8 @@ test_expect_success 'full repack creates bitmaps' '
ls .git/objects/pack/ | grep bitmap >output &&
test_line_count = 1 output &&
grep "\"key\":\"num_selected_commits\",\"value\":\"106\"" trace &&
- grep "\"key\":\"num_maximal_commits\",\"value\":\"107\"" trace
+ grep "\"key\":\"num_maximal_commits\",\"value\":\"107\"" trace &&
+ grep "\"label\":\"writing_lookup_table\"" trace
'
basic_bitmap_tests
diff --git a/t/t5326-multi-pack-bitmaps.sh b/t/t5326-multi-pack-bitmaps.sh
index 4fe57414c13..43be49617b8 100755
--- a/t/t5326-multi-pack-bitmaps.sh
+++ b/t/t5326-multi-pack-bitmaps.sh
@@ -307,4 +307,17 @@ test_expect_success 'graceful fallback when missing reverse index' '
)
'
+test_expect_success 'multi-pack-index write writes lookup table if enabled' '
+ rm -fr repo &&
+ git init repo &&
+ test_when_finished "rm -fr repo" &&
+ (
+ cd repo &&
+ test_commit base &&
+ git repack -ad &&
+ GIT_TRACE2_EVENT="$(pwd)/trace" \
+ git multi-pack-index write --bitmap &&
+ grep "\"label\":\"writing_lookup_table\"" trace
+ )
+'
test_done
--
gitgitgadget
