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[RFC PATCH 1/6] bloom: annotate filters with hash version

From
Taylor Blau <me@ttaylorr.com>
Date
Aug 7, 2023, 16:37 UTC
Message-ID
<e23a956401c5619bd46e8ec9b0e1df958cbcbfec.1691426160.git.me@ttaylorr.com>
In-Reply-To
<cover.1691426160.git.me@ttaylorr.com>

In subsequent commits, we will want to load existing Bloom filters out of a commit-graph, even when the hash version they were computed with does not match the value of `commitGraph.changedPathVersion`.

In order to differentiate between the two, add a "filter" field to each Bloom filter.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 bloom.c | 11 ++++++++---
 bloom.h |  1 +
 2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/bloom.c b/bloom.c
index ebef5cfd2f..9b6a30f6f6 100644
--- a/bloom.c
+++ b/bloom.c
@@ -55,6 +55,7 @@ int load_bloom_filter_from_graph(struct commit_graph *g,
 	filter->data = (unsigned char *)(g->chunk_bloom_data +
 					sizeof(unsigned char) * start_index +
 					BLOOMDATA_CHUNK_HEADER_SIZE);
+	filter->version = g->bloom_filter_settings->hash_version;
 
 	return 1;
 }
@@ -240,11 +241,13 @@ static int pathmap_cmp(const void *hashmap_cmp_fn_data UNUSED,
 	return strcmp(e1->path, e2->path);
 }
 
-static void init_truncated_large_filter(struct bloom_filter *filter)
+static void init_truncated_large_filter(struct bloom_filter *filter,
+					int version)
 {
 	filter->data = xmalloc(1);
 	filter->data[0] = 0xFF;
 	filter->len = 1;
+	filter->version = version;
 }
 
 struct bloom_filter *get_or_compute_bloom_filter(struct repository *r,
@@ -329,13 +332,15 @@ struct bloom_filter *get_or_compute_bloom_filter(struct repository *r,
 		}
 
 		if (hashmap_get_size(&pathmap) > settings->max_changed_paths) {
-			init_truncated_large_filter(filter);
+			init_truncated_large_filter(filter,
+						    settings->hash_version);
 			if (computed)
 				*computed |= BLOOM_TRUNC_LARGE;
 			goto cleanup;
 		}
 
 		filter->len = (hashmap_get_size(&pathmap) * settings->bits_per_entry + BITS_PER_WORD - 1) / BITS_PER_WORD;
+		filter->version = settings->hash_version;
 		if (!filter->len) {
 			if (computed)
 				*computed |= BLOOM_TRUNC_EMPTY;
@@ -355,7 +360,7 @@ struct bloom_filter *get_or_compute_bloom_filter(struct repository *r,
 	} else {
 		for (i = 0; i < diff_queued_diff.nr; i++)
 			diff_free_filepair(diff_queued_diff.queue[i]);
-		init_truncated_large_filter(filter);
+		init_truncated_large_filter(filter, settings->hash_version);
 
 		if (computed)
 			*computed |= BLOOM_TRUNC_LARGE;
diff --git a/bloom.h b/bloom.h
index 138d57a86b..330a140520 100644
--- a/bloom.h
+++ b/bloom.h
@@ -55,6 +55,7 @@ struct bloom_filter_settings {
 struct bloom_filter {
 	unsigned char *data;
 	size_t len;
+	int version;
 };
 
 /*
-- 
2.41.0.407.g6d1c33951b
Previous: Taylor BlauNext: Jonathan Tan
Message 17 of 24 in “bloom: reuse existing Bloom filters when possible during upgrade”
  1. 0/6 bloom: reuse existing Bloom filters when possible during upgradeTaylor Blau, Aug 7, 2023
  2. 3/6 t/t4216-log-bloom.sh: harden `test_bloom_filters_not_used()`Taylor Blau, Aug 7, 2023
  3. 4/6 commit-graph.c: unconditionally load Bloom filtersTaylor Blau, Aug 7, 2023
  4. Jonathan TanAug 11, 2023
  5. Taylor BlauAug 21, 2023
  6. 2/6 bloom: prepare to discard incompatible Bloom filtersTaylor Blau, Aug 7, 2023
  7. Jonathan TanAug 11, 2023
  8. Taylor BlauAug 21, 2023
  9. Jonathan TanAug 24, 2023
  10. Taylor BlauAug 24, 2023
  11. Jonathan TanAug 24, 2023
  12. Taylor BlauAug 25, 2023
  13. Jonathan TanAug 29, 2023
  14. Taylor BlauAug 29, 2023
  15. Jonathan TanAug 29, 2023
  16. 5/6 object.h: fix mis-aligned flag bits tableTaylor Blau, Aug 7, 2023
  17. 1/6 bloom: annotate filters with hash versionTaylor Blau, Aug 7, 2023
  18. Jonathan TanAug 11, 2023
  19. Taylor BlauAug 17, 2023
  20. Taylor BlauAug 21, 2023
  21. 6/6 commit-graph: reuse existing Bloom filters where possibleTaylor Blau, Aug 7, 2023
  22. Jonathan TanAug 11, 2023
  23. Jonathan TanAug 11, 2023
  24. Taylor BlauAug 21, 2023

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