---
Makefile | 1 +
bloom-filter.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++++
bloom-filter.h | 39 +++++++++++++++++++
3 files changed, 143 insertions(+)
create mode 100644 bloom-filter.c
create mode 100644 bloom-filter.h
diff --git a/Makefile b/Makefile
index 13e1c52478..850eafb3ee 100644
--- a/Makefile
+++ b/Makefile
@@ -827,6 +827,7 @@ LIB_OBJS += base85.o
LIB_OBJS += bisect.o
LIB_OBJS += blame.o
LIB_OBJS += blob.o
+LIB_OBJS += bloom-filter.o
LIB_OBJS += branch.o
LIB_OBJS += bulk-checkin.o
LIB_OBJS += bundle.o
diff --git a/bloom-filter.c b/bloom-filter.c
new file mode 100644
index 0000000000..7dce0e35fa
--- /dev/null
+++ b/bloom-filter.c
@@ -0,0 +1,103 @@
+#include "cache.h"
+#include "bloom-filter.h"
+
+void bloom_filter_init(struct bloom_filter *bf, uint32_t bit_size)
+{
+ if (bit_size % CHAR_BIT)
+ BUG("invalid size for bloom filter");
+
+ bf->nr_entries = 0;
+ bf->bit_size = bit_size;
+ bf->bits = xmalloc(bit_size / CHAR_BIT);
+}
+
+void bloom_filter_free(struct bloom_filter *bf)
+{
+ bf->nr_entries = 0;
+ bf->bit_size = 0;
+ FREE_AND_NULL(bf->bits);
+}
+
+
+void bloom_filter_set_bits(struct bloom_filter *bf, const uint32_t *offsets,
+ int nr_offsets, int nr_entries)
+{
+ int i;
+ for (i = 0; i < nr_offsets; i++) {
+ uint32_t byte_offset = (offsets[i] % bf->bit_size) / CHAR_BIT;
+ unsigned char mask = 1 << offsets[i] % CHAR_BIT;
+ bf->bits[byte_offset] |= mask;
+ }
+ bf->nr_entries += nr_entries;
+}
+
+int bloom_filter_check_bits(struct bloom_filter *bf, const uint32_t *offsets,
+ int nr)
+{
+ int i;
+ for (i = 0; i < nr; i++) {
+ uint32_t byte_offset = (offsets[i] % bf->bit_size) / CHAR_BIT;
+ unsigned char mask = 1 << offsets[i] % CHAR_BIT;
+ if (!(bf->bits[byte_offset] & mask))
+ return 0;
+ }
+ return 1;
+}
+
+
+void bloom_filter_add_hash(struct bloom_filter *bf, const unsigned char *hash)
+{
+ uint32_t offsets[GIT_MAX_RAWSZ / sizeof(uint32_t)];
+ hashcpy((unsigned char*)offsets, hash);
+ bloom_filter_set_bits(bf, offsets,
+ the_hash_algo->rawsz / sizeof(*offsets), 1);
+}
+
+int bloom_filter_check_hash(struct bloom_filter *bf, const unsigned char *hash)
+{
+ uint32_t offsets[GIT_MAX_RAWSZ / sizeof(uint32_t)];
+ hashcpy((unsigned char*)offsets, hash);
+ return bloom_filter_check_bits(bf, offsets,
+ the_hash_algo->rawsz / sizeof(*offsets));
+}
+
+void hashxor(const unsigned char *hash1, const unsigned char *hash2,
+ unsigned char *out)
+{
+ int i;
+ for (i = 0; i < the_hash_algo->rawsz; i++)
+ out[i] = hash1[i] ^ hash2[i];
+}
+
+/* hardcoded for now... */
+static GIT_PATH_FUNC(git_path_bloom, "objects/info/bloom")
+
+int bloom_filter_load(struct bloom_filter *bf)
+{
+ int fd = open(git_path_bloom(), O_RDONLY);
+
+ if (fd < 0)
+ return -1;
+
+ read_in_full(fd, &bf->nr_entries, sizeof(bf->nr_entries));
+ read_in_full(fd, &bf->bit_size, sizeof(bf->bit_size));
+ if (bf->bit_size % CHAR_BIT)
+ BUG("invalid size for bloom filter");
+ bf->bits = xmalloc(bf->bit_size / CHAR_BIT);
+ read_in_full(fd, bf->bits, bf->bit_size / CHAR_BIT);
+
+ close(fd);
+
+ return 0;
+}
+
+void bloom_filter_write(struct bloom_filter *bf)
+{
+ int fd = xopen(git_path_bloom(), O_WRONLY | O_CREAT | O_TRUNC, 0666);
+
+ write_in_full(fd, &bf->nr_entries, sizeof(bf->nr_entries));
+ write_in_full(fd, &bf->bit_size, sizeof(bf->bit_size));
+ write_in_full(fd, bf->bits, bf->bit_size / CHAR_BIT);
+
+ close(fd);
+}
diff --git a/bloom-filter.h b/bloom-filter.h
new file mode 100644
index 0000000000..94d0af1708
--- /dev/null
+++ b/bloom-filter.h
@@ -0,0 +1,39 @@
+#ifndef BLOOM_FILTER_H
+#define BLOOM_FILTER_H
+
+#include "git-compat-util.h"
+
+struct bloom_filter {
+ uint32_t nr_entries;
+ uint32_t bit_size;
+ unsigned char *bits;
+};
+
+
+void bloom_filter_init(struct bloom_filter *bf, uint32_t bit_size);
+void bloom_filter_free(struct bloom_filter *bf);
+
+void bloom_filter_set_bits(struct bloom_filter *bf, const uint32_t *offsets,
+ int nr_offsets, int nr_enries);
+int bloom_filter_check_bits(struct bloom_filter *bf, const uint32_t *offsets,
+ int nr);
+
+/*
+ * Turns the given (SHA1) hash into 5 unsigned ints, and sets the bits at
+ * those positions (modulo the bitmap's size) in the Bloom filter.
+ */
+void bloom_filter_add_hash(struct bloom_filter *bf, const unsigned char *hash);
+/*
+ * Turns the given (SHA1) hash into 5 unsigned ints, and checks the bits at
+ * those positions (modulo the bitmap's size) in the Bloom filter.
+ * Returns 1 if all those bits are set, 0 otherwise.
+ */
+int bloom_filter_check_hash(struct bloom_filter *bf, const unsigned char *hash);
+
+void hashxor(const unsigned char *hash1, const unsigned char *hash2,
+ unsigned char *out);
+
+int bloom_filter_load(struct bloom_filter *bf);
+void bloom_filter_write(struct bloom_filter *bf);
+
+#endif
--
2.19.1.409.g0a0ee5eb6b
