From: Garima Singh <garima.singh@xxxxxxxxxxxxx>
Add logic to
a) parse Bloom filter information from the commit graph file and,
b) re-use existing Bloom filters.
See Documentation/technical/commit-graph-format for the format in which
the Bloom filter information is written to the commit graph file.
To read Bloom filter for a given commit with lexicographic position
'i' we need to:
1. Read BIDX[i] which essentially gives us the starting index in BDAT for
filter of commit i+1. It is essentially the index past the end
of the filter of commit i. It is called end_index in the code.
2. For i>0, read BIDX[i-1] which will give us the starting index in BDAT
for filter of commit i. It is called the start_index in the code.
For the first commit, where i = 0, Bloom filter data starts at the
beginning, just past the header in the BDAT chunk. Hence, start_index
will be 0.
3. The length of the filter will be end_index - start_index, because
BIDX[i] gives the cumulative 8-byte words including the ith
commit's filter.
We toggle whether Bloom filters should be recomputed based on the
compute_if_not_present flag.
Helped-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
Signed-off-by: Garima Singh <garima.singh@xxxxxxxxxxxxx>
---
bloom.c | 49 ++++++++++++++++++++++++++++++++++++++++++-
bloom.h | 4 +++-
commit-graph.c | 6 +++---
t/helper/test-bloom.c | 2 +-
4 files changed, 55 insertions(+), 6 deletions(-)
diff --git a/bloom.c b/bloom.c
index a16eee92331..0f714dd76ae 100644
--- a/bloom.c
+++ b/bloom.c
@@ -4,6 +4,8 @@
#include "diffcore.h"
#include "revision.h"
#include "hashmap.h"
+#include "commit-graph.h"
+#include "commit.h"
define_commit_slab(bloom_filter_slab, struct bloom_filter);
@@ -26,6 +28,36 @@ static inline unsigned char get_bitmask(uint32_t pos)
return ((unsigned char)1) << (pos & (BITS_PER_WORD - 1));
}
+static int load_bloom_filter_from_graph(struct commit_graph *g,
+ struct bloom_filter *filter,
+ struct commit *c)
+{
+ uint32_t lex_pos, start_index, end_index;
+
+ while (c->graph_pos < g->num_commits_in_base)
+ g = g->base_graph;
+
+ /* The commit graph commit 'c' lives in doesn't carry bloom filters. */
+ if (!g->chunk_bloom_indexes)
+ return 0;
+
+ lex_pos = c->graph_pos - g->num_commits_in_base;
+
+ end_index = get_be32(g->chunk_bloom_indexes + 4 * lex_pos);
+
+ if (lex_pos > 0)
+ start_index = get_be32(g->chunk_bloom_indexes + 4 * (lex_pos - 1));
+ else
+ start_index = 0;
+
+ filter->len = end_index - start_index;
+ filter->data = (unsigned char *)(g->chunk_bloom_data +
+ sizeof(unsigned char) * start_index +
+ BLOOMDATA_CHUNK_HEADER_SIZE);
+
+ return 1;
+}
+
/*
* Calculate the murmur3 32-bit hash value for the given data
* using the given seed.
@@ -127,7 +159,8 @@ void init_bloom_filters(void)
}
struct bloom_filter *get_bloom_filter(struct repository *r,
- struct commit *c)
+ struct commit *c,
+ int compute_if_not_present)
{
struct bloom_filter *filter;
struct bloom_filter_settings settings = DEFAULT_BLOOM_FILTER_SETTINGS;
@@ -140,6 +173,20 @@ struct bloom_filter *get_bloom_filter(struct repository *r,
filter = bloom_filter_slab_at(&bloom_filters, c);
+ if (!filter->data) {
+ load_commit_graph_info(r, c);
+ if (c->graph_pos != COMMIT_NOT_FROM_GRAPH &&
+ r->objects->commit_graph->chunk_bloom_indexes) {
+ if (load_bloom_filter_from_graph(r->objects->commit_graph, filter, c))
+ return filter;
+ else
+ return NULL;
+ }
+ }
+
+ if (filter->data || !compute_if_not_present)
+ return filter;
+
repo_diff_setup(r, &diffopt);
diffopt.flags.recursive = 1;
diffopt.max_changes = max_changes;
diff --git a/bloom.h b/bloom.h
index 85ab8e9423d..760d7122374 100644
--- a/bloom.h
+++ b/bloom.h
@@ -32,6 +32,7 @@ struct bloom_filter_settings {
#define DEFAULT_BLOOM_FILTER_SETTINGS { 1, 7, 10 }
#define BITS_PER_WORD 8
+#define BLOOMDATA_CHUNK_HEADER_SIZE 3 * sizeof(uint32_t)
/*
* A bloom_filter struct represents a data segment to
@@ -79,6 +80,7 @@ void add_key_to_filter(const struct bloom_key *key,
void init_bloom_filters(void);
struct bloom_filter *get_bloom_filter(struct repository *r,
- struct commit *c);
+ struct commit *c,
+ int compute_if_not_present);
#endif
\ No newline at end of file
diff --git a/commit-graph.c b/commit-graph.c
index a8b6b5cca5d..77668629e27 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -1086,7 +1086,7 @@ static void write_graph_chunk_bloom_indexes(struct hashfile *f,
ctx->commits.nr);
while (list < last) {
- struct bloom_filter *filter = get_bloom_filter(ctx->r, *list);
+ struct bloom_filter *filter = get_bloom_filter(ctx->r, *list, 0);
cur_pos += filter->len;
display_progress(progress, ++i);
hashwrite_be32(f, cur_pos);
@@ -1115,7 +1115,7 @@ static void write_graph_chunk_bloom_data(struct hashfile *f,
hashwrite_be32(f, settings->bits_per_entry);
while (list < last) {
- struct bloom_filter *filter = get_bloom_filter(ctx->r, *list);
+ struct bloom_filter *filter = get_bloom_filter(ctx->r, *list, 0);
display_progress(progress, ++i);
hashwrite(f, filter->data, filter->len * sizeof(unsigned char));
list++;
@@ -1296,7 +1296,7 @@ static void compute_bloom_filters(struct write_commit_graph_context *ctx)
for (i = 0; i < ctx->commits.nr; i++) {
struct commit *c = sorted_commits[i];
- struct bloom_filter *filter = get_bloom_filter(ctx->r, c);
+ struct bloom_filter *filter = get_bloom_filter(ctx->r, c, 1);
ctx->total_bloom_filter_data_size += sizeof(unsigned char) * filter->len;
display_progress(progress, i + 1);
}
diff --git a/t/helper/test-bloom.c b/t/helper/test-bloom.c
index f18d1b722e1..ce412664ba9 100644
--- a/t/helper/test-bloom.c
+++ b/t/helper/test-bloom.c
@@ -39,7 +39,7 @@ static void get_bloom_filter_for_commit(const struct object_id *commit_oid)
struct bloom_filter *filter;
setup_git_directory();
c = lookup_commit(the_repository, commit_oid);
- filter = get_bloom_filter(the_repository, c);
+ filter = get_bloom_filter(the_repository, c, 1);
print_bloom_filter(filter);
}
--
gitgitgadget
