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![Ævar Arnfjörð Bjarmason](/assets/img/avatar_default.png)
As reported in [1] the "UNUSED(var)" macro introduced in2174b8c75d
(Merge branch 'jk/unused-annotation' into next, 2022-08-24) breaks coccinelle's parsing of our sources in files where it occurs. Let's instead partially go with the approach suggested in [2] of making this not take an argument. As noted in [1] "coccinelle" will ignore such tokens in argument lists that it doesn't know about, and it's less of a surprise to syntax highlighters. This undoes the "help us notice when a parameter marked as unused is actually use" part of9b24034754
(git-compat-util: add UNUSED macro, 2022-08-19), a subsequent commit will further tweak the macro to implement a replacement for that functionality. 1. https://lore.kernel.org/git/220825.86ilmg4mil.gmgdl@evledraar.gmail.com/ 2. https://lore.kernel.org/git/220819.868rnk54ju.gmgdl@evledraar.gmail.com/ Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
328 lines
8 KiB
C
328 lines
8 KiB
C
#include "git-compat-util.h"
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#include "bloom.h"
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#include "diff.h"
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#include "diffcore.h"
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#include "revision.h"
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#include "hashmap.h"
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#include "commit-graph.h"
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#include "commit.h"
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define_commit_slab(bloom_filter_slab, struct bloom_filter);
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static struct bloom_filter_slab bloom_filters;
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struct pathmap_hash_entry {
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struct hashmap_entry entry;
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const char path[FLEX_ARRAY];
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};
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static uint32_t rotate_left(uint32_t value, int32_t count)
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{
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uint32_t mask = 8 * sizeof(uint32_t) - 1;
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count &= mask;
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return ((value << count) | (value >> ((-count) & mask)));
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}
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static inline unsigned char get_bitmask(uint32_t pos)
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{
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return ((unsigned char)1) << (pos & (BITS_PER_WORD - 1));
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}
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static int load_bloom_filter_from_graph(struct commit_graph *g,
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struct bloom_filter *filter,
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uint32_t graph_pos)
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{
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uint32_t lex_pos, start_index, end_index;
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while (graph_pos < g->num_commits_in_base)
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g = g->base_graph;
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/* The commit graph commit 'c' lives in doesn't carry Bloom filters. */
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if (!g->chunk_bloom_indexes)
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return 0;
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lex_pos = graph_pos - g->num_commits_in_base;
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end_index = get_be32(g->chunk_bloom_indexes + 4 * lex_pos);
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if (lex_pos > 0)
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start_index = get_be32(g->chunk_bloom_indexes + 4 * (lex_pos - 1));
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else
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start_index = 0;
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filter->len = end_index - start_index;
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filter->data = (unsigned char *)(g->chunk_bloom_data +
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sizeof(unsigned char) * start_index +
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BLOOMDATA_CHUNK_HEADER_SIZE);
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return 1;
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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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{
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const uint32_t c1 = 0xcc9e2d51;
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const uint32_t c2 = 0x1b873593;
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const uint32_t r1 = 15;
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const uint32_t r2 = 13;
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const uint32_t m = 5;
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const uint32_t n = 0xe6546b64;
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int i;
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uint32_t k1 = 0;
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const char *tail;
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int len4 = len / sizeof(uint32_t);
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uint32_t k;
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for (i = 0; i < len4; i++) {
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uint32_t byte1 = (uint32_t)data[4*i];
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uint32_t byte2 = ((uint32_t)data[4*i + 1]) << 8;
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uint32_t byte3 = ((uint32_t)data[4*i + 2]) << 16;
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uint32_t byte4 = ((uint32_t)data[4*i + 3]) << 24;
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k = byte1 | byte2 | byte3 | byte4;
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k *= c1;
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k = rotate_left(k, r1);
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k *= c2;
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seed ^= k;
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seed = rotate_left(seed, r2) * m + n;
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}
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tail = (data + len4 * sizeof(uint32_t));
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switch (len & (sizeof(uint32_t) - 1)) {
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case 3:
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k1 ^= ((uint32_t)tail[2]) << 16;
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/*-fallthrough*/
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case 2:
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k1 ^= ((uint32_t)tail[1]) << 8;
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/*-fallthrough*/
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case 1:
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k1 ^= ((uint32_t)tail[0]) << 0;
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k1 *= c1;
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k1 = rotate_left(k1, r1);
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k1 *= c2;
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seed ^= k1;
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break;
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}
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seed ^= (uint32_t)len;
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seed ^= (seed >> 16);
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seed *= 0x85ebca6b;
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seed ^= (seed >> 13);
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seed *= 0xc2b2ae35;
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seed ^= (seed >> 16);
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return seed;
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}
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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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{
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int i;
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const uint32_t seed0 = 0x293ae76f;
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const uint32_t seed1 = 0x7e646e2c;
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const uint32_t hash0 = murmur3_seeded(seed0, data, len);
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const uint32_t hash1 = murmur3_seeded(seed1, data, len);
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key->hashes = (uint32_t *)xcalloc(settings->num_hashes, sizeof(uint32_t));
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for (i = 0; i < settings->num_hashes; i++)
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key->hashes[i] = hash0 + i * hash1;
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}
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void clear_bloom_key(struct bloom_key *key)
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{
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FREE_AND_NULL(key->hashes);
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}
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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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{
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int i;
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uint64_t mod = filter->len * BITS_PER_WORD;
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for (i = 0; i < settings->num_hashes; i++) {
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uint64_t hash_mod = key->hashes[i] % mod;
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uint64_t block_pos = hash_mod / BITS_PER_WORD;
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filter->data[block_pos] |= get_bitmask(hash_mod);
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}
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}
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void init_bloom_filters(void)
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{
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init_bloom_filter_slab(&bloom_filters);
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}
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static int pathmap_cmp(const void *hashmap_cmp_fn_data UNUSED,
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const struct hashmap_entry *eptr,
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const struct hashmap_entry *entry_or_key,
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const void *keydata UNUSED)
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{
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const struct pathmap_hash_entry *e1, *e2;
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e1 = container_of(eptr, const struct pathmap_hash_entry, entry);
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e2 = container_of(entry_or_key, const struct pathmap_hash_entry, entry);
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return strcmp(e1->path, e2->path);
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}
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static void init_truncated_large_filter(struct bloom_filter *filter)
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{
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filter->data = xmalloc(1);
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filter->data[0] = 0xFF;
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filter->len = 1;
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}
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struct bloom_filter *get_or_compute_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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const struct bloom_filter_settings *settings,
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enum bloom_filter_computed *computed)
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{
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struct bloom_filter *filter;
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int i;
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struct diff_options diffopt;
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if (computed)
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*computed = BLOOM_NOT_COMPUTED;
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if (!bloom_filters.slab_size)
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return NULL;
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filter = bloom_filter_slab_at(&bloom_filters, c);
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if (!filter->data) {
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uint32_t graph_pos;
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if (repo_find_commit_pos_in_graph(r, c, &graph_pos))
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load_bloom_filter_from_graph(r->objects->commit_graph,
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filter, graph_pos);
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}
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if (filter->data && filter->len)
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return filter;
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if (!compute_if_not_present)
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return NULL;
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repo_diff_setup(r, &diffopt);
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diffopt.flags.recursive = 1;
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diffopt.detect_rename = 0;
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diffopt.max_changes = settings->max_changed_paths;
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diff_setup_done(&diffopt);
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/* ensure commit is parsed so we have parent information */
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repo_parse_commit(r, c);
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if (c->parents)
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diff_tree_oid(&c->parents->item->object.oid, &c->object.oid, "", &diffopt);
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else
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diff_tree_oid(NULL, &c->object.oid, "", &diffopt);
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diffcore_std(&diffopt);
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if (diff_queued_diff.nr <= settings->max_changed_paths) {
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struct hashmap pathmap = HASHMAP_INIT(pathmap_cmp, NULL);
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struct pathmap_hash_entry *e;
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struct hashmap_iter iter;
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for (i = 0; i < diff_queued_diff.nr; i++) {
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const char *path = diff_queued_diff.queue[i]->two->path;
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/*
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* Add each leading directory of the changed file, i.e. for
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* 'dir/subdir/file' add 'dir' and 'dir/subdir' as well, so
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* the Bloom filter could be used to speed up commands like
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* 'git log dir/subdir', too.
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*
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* Note that directories are added without the trailing '/'.
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*/
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do {
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char *last_slash = strrchr(path, '/');
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FLEX_ALLOC_STR(e, path, path);
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hashmap_entry_init(&e->entry, strhash(path));
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if (!hashmap_get(&pathmap, &e->entry, NULL))
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hashmap_add(&pathmap, &e->entry);
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else
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free(e);
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if (!last_slash)
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last_slash = (char*)path;
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*last_slash = '\0';
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} while (*path);
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diff_free_filepair(diff_queued_diff.queue[i]);
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}
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if (hashmap_get_size(&pathmap) > settings->max_changed_paths) {
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init_truncated_large_filter(filter);
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if (computed)
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*computed |= BLOOM_TRUNC_LARGE;
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goto cleanup;
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}
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filter->len = (hashmap_get_size(&pathmap) * settings->bits_per_entry + BITS_PER_WORD - 1) / BITS_PER_WORD;
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if (!filter->len) {
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if (computed)
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*computed |= BLOOM_TRUNC_EMPTY;
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filter->len = 1;
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}
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CALLOC_ARRAY(filter->data, filter->len);
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hashmap_for_each_entry(&pathmap, &iter, e, entry) {
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struct bloom_key key;
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fill_bloom_key(e->path, strlen(e->path), &key, settings);
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add_key_to_filter(&key, filter, settings);
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clear_bloom_key(&key);
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}
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cleanup:
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hashmap_clear_and_free(&pathmap, struct pathmap_hash_entry, entry);
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} else {
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for (i = 0; i < diff_queued_diff.nr; i++)
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diff_free_filepair(diff_queued_diff.queue[i]);
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init_truncated_large_filter(filter);
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if (computed)
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*computed |= BLOOM_TRUNC_LARGE;
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}
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if (computed)
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*computed |= BLOOM_COMPUTED;
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free(diff_queued_diff.queue);
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DIFF_QUEUE_CLEAR(&diff_queued_diff);
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return filter;
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}
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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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{
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int i;
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uint64_t mod = filter->len * BITS_PER_WORD;
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if (!mod)
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return -1;
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for (i = 0; i < settings->num_hashes; i++) {
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uint64_t hash_mod = key->hashes[i] % mod;
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uint64_t block_pos = hash_mod / BITS_PER_WORD;
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if (!(filter->data[block_pos] & get_bitmask(hash_mod)))
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return 0;
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}
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return 1;
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}
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