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2834bc27c1
The hash table that stores the packing list for a given `pack-objects` run was tightly coupled to the pack-objects code. In this commit, we refactor the hash table and the underlying storage array into a `packing_data` struct. The functionality for accessing and adding entries to the packing list is hence accessible from other parts of Git besides the `pack-objects` builtin. This refactoring is a requirement for further patches in this series that will require accessing the commit packing list from outside of `pack-objects`. The hash table implementation has been minimally altered: we now use table sizes which are always a power of two, to ensure a uniform index distribution in the array. Signed-off-by: Vicent Marti <tanoku@gmail.com> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
111 lines
2.2 KiB
C
111 lines
2.2 KiB
C
#include "cache.h"
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#include "object.h"
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#include "pack.h"
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#include "pack-objects.h"
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static uint32_t locate_object_entry_hash(struct packing_data *pdata,
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const unsigned char *sha1,
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int *found)
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{
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uint32_t i, hash, mask = (pdata->index_size - 1);
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memcpy(&hash, sha1, sizeof(uint32_t));
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i = hash & mask;
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while (pdata->index[i] > 0) {
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uint32_t pos = pdata->index[i] - 1;
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if (!hashcmp(sha1, pdata->objects[pos].idx.sha1)) {
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*found = 1;
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return i;
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}
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i = (i + 1) & mask;
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}
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*found = 0;
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return i;
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}
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static inline uint32_t closest_pow2(uint32_t v)
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{
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v = v - 1;
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v |= v >> 1;
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v |= v >> 2;
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v |= v >> 4;
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v |= v >> 8;
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v |= v >> 16;
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return v + 1;
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}
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static void rehash_objects(struct packing_data *pdata)
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{
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uint32_t i;
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struct object_entry *entry;
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pdata->index_size = closest_pow2(pdata->nr_objects * 3);
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if (pdata->index_size < 1024)
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pdata->index_size = 1024;
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pdata->index = xrealloc(pdata->index, sizeof(uint32_t) * pdata->index_size);
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memset(pdata->index, 0, sizeof(int) * pdata->index_size);
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entry = pdata->objects;
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for (i = 0; i < pdata->nr_objects; i++) {
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int found;
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uint32_t ix = locate_object_entry_hash(pdata, entry->idx.sha1, &found);
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if (found)
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die("BUG: Duplicate object in hash");
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pdata->index[ix] = i + 1;
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entry++;
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}
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}
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struct object_entry *packlist_find(struct packing_data *pdata,
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const unsigned char *sha1,
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uint32_t *index_pos)
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{
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uint32_t i;
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int found;
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if (!pdata->index_size)
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return NULL;
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i = locate_object_entry_hash(pdata, sha1, &found);
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if (index_pos)
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*index_pos = i;
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if (!found)
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return NULL;
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return &pdata->objects[pdata->index[i] - 1];
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}
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struct object_entry *packlist_alloc(struct packing_data *pdata,
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const unsigned char *sha1,
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uint32_t index_pos)
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{
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struct object_entry *new_entry;
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if (pdata->nr_objects >= pdata->nr_alloc) {
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pdata->nr_alloc = (pdata->nr_alloc + 1024) * 3 / 2;
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pdata->objects = xrealloc(pdata->objects,
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pdata->nr_alloc * sizeof(*new_entry));
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}
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new_entry = pdata->objects + pdata->nr_objects++;
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memset(new_entry, 0, sizeof(*new_entry));
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hashcpy(new_entry->idx.sha1, sha1);
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if (pdata->index_size * 3 <= pdata->nr_objects * 4)
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rehash_objects(pdata);
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else
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pdata->index[index_pos] = pdata->nr_objects;
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return new_entry;
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}
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