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83f0412f3f
When growing the table, take the opportunity to "compact" it by removing entries with NULL decoration. Users may have "removed" decorations by passing NULL to insert_decoration. An object's table entry can't actually be removed during normal operation, as it would break the linear hash collision search. But we can remove NULL decoration entries when rebuilding the table. Signed-off-by: Kevin Bracey <kevin@bracey.fi> Signed-off-by: Junio C Hamano <gitster@pobox.com>
88 lines
1.8 KiB
C
88 lines
1.8 KiB
C
/*
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* decorate.c - decorate a git object with some arbitrary
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* data.
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*/
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#include "cache.h"
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#include "object.h"
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#include "decorate.h"
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static unsigned int hash_obj(const struct object *obj, unsigned int n)
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{
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unsigned int hash;
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memcpy(&hash, obj->sha1, sizeof(unsigned int));
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return hash % n;
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}
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static void *insert_decoration(struct decoration *n, const struct object *base, void *decoration)
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{
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int size = n->size;
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struct object_decoration *hash = n->hash;
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unsigned int j = hash_obj(base, size);
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while (hash[j].base) {
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if (hash[j].base == base) {
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void *old = hash[j].decoration;
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hash[j].decoration = decoration;
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return old;
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}
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if (++j >= size)
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j = 0;
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}
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hash[j].base = base;
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hash[j].decoration = decoration;
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n->nr++;
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return NULL;
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}
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static void grow_decoration(struct decoration *n)
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{
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int i;
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int old_size = n->size;
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struct object_decoration *old_hash = n->hash;
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n->size = (old_size + 1000) * 3 / 2;
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n->hash = xcalloc(n->size, sizeof(struct object_decoration));
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n->nr = 0;
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for (i = 0; i < old_size; i++) {
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const struct object *base = old_hash[i].base;
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void *decoration = old_hash[i].decoration;
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if (!decoration)
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continue;
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insert_decoration(n, base, decoration);
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}
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free(old_hash);
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}
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/* Add a decoration pointer, return any old one */
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void *add_decoration(struct decoration *n, const struct object *obj,
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void *decoration)
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{
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int nr = n->nr + 1;
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if (nr > n->size * 2 / 3)
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grow_decoration(n);
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return insert_decoration(n, obj, decoration);
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}
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/* Lookup a decoration pointer */
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void *lookup_decoration(struct decoration *n, const struct object *obj)
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{
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unsigned int j;
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/* nothing to lookup */
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if (!n->size)
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return NULL;
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j = hash_obj(obj, n->size);
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for (;;) {
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struct object_decoration *ref = n->hash + j;
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if (ref->base == obj)
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return ref->decoration;
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if (!ref->base)
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return NULL;
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if (++j == n->size)
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j = 0;
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}
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}
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