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c3a02824cf
"git log -L..." now takes advantage of the "which paths are touched by this commit?" info stored in the commit-graph system. * ds/line-log-on-bloom: line-log: integrate with changed-path Bloom filters line-log: try to use generation number-based topo-ordering line-log: more responsive, incremental 'git log -L' t4211-line-log: add tests for parent oids line-log: remove unused fields from 'struct line_log_data'
92 lines
2.4 KiB
C
92 lines
2.4 KiB
C
#ifndef BLOOM_H
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#define BLOOM_H
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struct commit;
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struct repository;
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struct bloom_filter_settings {
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/*
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* The version of the hashing technique being used.
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* We currently only support version = 1 which is
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* the seeded murmur3 hashing technique implemented
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* in bloom.c.
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*/
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uint32_t hash_version;
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/*
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* The number of times a path is hashed, i.e. the
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* number of bit positions tht cumulatively
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* determine whether a path is present in the
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* Bloom filter.
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*/
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uint32_t num_hashes;
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/*
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* The minimum number of bits per entry in the Bloom
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* filter. If the filter contains 'n' entries, then
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* filter size is the minimum number of 8-bit words
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* that contain n*b bits.
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*/
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uint32_t bits_per_entry;
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};
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#define DEFAULT_BLOOM_FILTER_SETTINGS { 1, 7, 10 }
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#define BITS_PER_WORD 8
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#define BLOOMDATA_CHUNK_HEADER_SIZE 3 * sizeof(uint32_t)
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/*
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* A bloom_filter struct represents a data segment to
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* use when testing hash values. The 'len' member
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* dictates how many entries are stored in
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* 'data'.
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*/
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struct bloom_filter {
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unsigned char *data;
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size_t len;
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};
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/*
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* A bloom_key represents the k hash values for a
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* given string. These can be precomputed and
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* stored in a bloom_key for re-use when testing
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* against a bloom_filter. The number of hashes is
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* given by the Bloom filter settings and is the same
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* for all Bloom filters and keys interacting with
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* the loaded version of the commit graph file and
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* the Bloom data chunks.
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*/
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struct bloom_key {
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uint32_t *hashes;
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};
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/*
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* Calculate the murmur3 32-bit hash value for the given data
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* using the given seed.
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* Produces a uniformly distributed hash value.
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* Not considered to be cryptographically secure.
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* Implemented as described in https://en.wikipedia.org/wiki/MurmurHash#Algorithm
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*/
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uint32_t murmur3_seeded(uint32_t seed, const char *data, size_t len);
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void fill_bloom_key(const char *data,
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size_t len,
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struct bloom_key *key,
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const struct bloom_filter_settings *settings);
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void clear_bloom_key(struct bloom_key *key);
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void add_key_to_filter(const struct bloom_key *key,
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struct bloom_filter *filter,
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const struct bloom_filter_settings *settings);
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void init_bloom_filters(void);
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struct bloom_filter *get_bloom_filter(struct repository *r,
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struct commit *c,
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int compute_if_not_present);
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int bloom_filter_contains(const struct bloom_filter *filter,
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const struct bloom_key *key,
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const struct bloom_filter_settings *settings);
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#endif
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