bloom: add test helper to return murmur3 hash

In bloom.h, murmur3_seeded_v2() is exported for the use of test murmur3
hash. To clarify that murmur3_seeded_v2() is exported solely for testing
purposes, a new helper function test_murmur3_seeded() was added instead
of exporting murmur3_seeded_v2() directly.

Signed-off-by: Lidong Yan <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: brandb97

bloom.c

@@ -107,7 +107,7 @@ int load_bloom_filter_from_graph(struct commit_graph *g,
  * Not considered to be cryptographically secure.
  * Implemented as described in https://en.wikipedia.org/wiki/MurmurHash#Algorithm
  */
-uint32_t murmur3_seeded_v2(uint32_t seed, const char *data, size_t len)
+static uint32_t murmur3_seeded_v2(uint32_t seed, const char *data, size_t len)
 {
 	const uint32_t c1 = 0xcc9e2d51;
 	const uint32_t c2 = 0x1b873593;
@@ -540,3 +540,14 @@ int bloom_filter_contains(const struct bloom_filter *filter,
 
 	return 1;
 }
+
+uint32_t test_bloom_murmur3_seeded(uint32_t seed, const char *data, size_t len,
+				   int version)
+{
+	assert(version == 1 || version == 2);
+
+	if (version == 2)
+		return murmur3_seeded_v2(seed, data, len);
+	else
+		return murmur3_seeded_v1(seed, data, len);
+}

bloom.h

@@ -78,15 +78,6 @@ int load_bloom_filter_from_graph(struct commit_graph *g,
 				 struct bloom_filter *filter,
 				 uint32_t graph_pos);
 
-/*
- * Calculate the murmur3 32-bit hash value for the given data
- * using the given seed.
- * Produces a uniformly distributed hash value.
- * Not considered to be cryptographically secure.
- * Implemented as described in https://en.wikipedia.org/wiki/MurmurHash#Algorithm
- */
-uint32_t murmur3_seeded_v2(uint32_t seed, const char *data, size_t len);
-
 void fill_bloom_key(const char *data,
 		    size_t len,
 		    struct bloom_key *key,
@@ -137,4 +128,7 @@ int bloom_filter_contains(const struct bloom_filter *filter,
 			  const struct bloom_key *key,
 			  const struct bloom_filter_settings *settings);
 
+uint32_t test_bloom_murmur3_seeded(uint32_t seed, const char *data, size_t len,
+				   int version);
+
 #endif

t/helper/test-bloom.c

@@ -61,13 +61,13 @@ int cmd__bloom(int argc, const char **argv)
 		uint32_t hashed;
 		if (argc < 3)
 			usage(bloom_usage);
-		hashed = murmur3_seeded_v2(0, argv[2], strlen(argv[2]));
+		hashed = test_bloom_murmur3_seeded(0, argv[2], strlen(argv[2]), 2);
 		printf("Murmur3 Hash with seed=0:0x%08x\n", hashed);
 	}
 
 	if (!strcmp(argv[1], "get_murmur3_seven_highbit")) {
 		uint32_t hashed;
-		hashed = murmur3_seeded_v2(0, "\x99\xaa\xbb\xcc\xdd\xee\xff", 7);
+		hashed = test_bloom_murmur3_seeded(0, "\x99\xaa\xbb\xcc\xdd\xee\xff", 7, 2);
 		printf("Murmur3 Hash with seed=0:0x%08x\n", hashed);
 	}