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f894081dea
Implement reading for multi-pack reverse indexes, as described in the
previous patch.
Note that these functions don't yet have any callers, and won't until
multi-pack reachability bitmaps are introduced in a later patch series.
In the meantime, this patch implements some of the infrastructure
necessary to support multi-pack bitmaps.
There are three new functions exposed by the revindex API:
- load_midx_revindex(): loads the reverse index corresponding to the
given multi-pack index.
- midx_to_pack_pos() and pack_pos_to_midx(): these convert between the
multi-pack index and pseudo-pack order.
load_midx_revindex() and pack_pos_to_midx() are both relatively
straightforward.
load_midx_revindex() needs a few functions to be exposed from the midx
API. One to get the checksum of a midx, and another to get the .rev's
filename. Similar to recent changes in the packed_git struct, three new
fields are added to the multi_pack_index struct: one to keep track of
the size, one to keep track of the mmap'd pointer, and another to point
past the header and at the reverse index's data.
pack_pos_to_midx() simply reads the corresponding entry out of the
table.
midx_to_pack_pos() is the trickiest, since it needs to find an object's
position in the psuedo-pack order, but that order can only be recovered
in the .rev file itself. This mapping can be implemented with a binary
search, but note that the thing we're binary searching over isn't an
array of values, but rather a permuted order of those values.
So, when comparing two items, it's helpful to keep in mind the
difference. Instead of a traditional binary search, where you are
comparing two things directly, here we're comparing a (pack, offset)
tuple with an index into the multi-pack index. That index describes
another (pack, offset) tuple, and it is _those_ two tuples that are
compared.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
67 lines
2.1 KiB
C
67 lines
2.1 KiB
C
#ifndef MIDX_H
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#define MIDX_H
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#include "repository.h"
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struct object_id;
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struct pack_entry;
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struct repository;
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#define GIT_TEST_MULTI_PACK_INDEX "GIT_TEST_MULTI_PACK_INDEX"
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struct multi_pack_index {
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struct multi_pack_index *next;
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const unsigned char *data;
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size_t data_len;
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const uint32_t *revindex_data;
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const uint32_t *revindex_map;
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size_t revindex_len;
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uint32_t signature;
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unsigned char version;
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unsigned char hash_len;
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unsigned char num_chunks;
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uint32_t num_packs;
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uint32_t num_objects;
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int local;
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const unsigned char *chunk_pack_names;
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const uint32_t *chunk_oid_fanout;
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const unsigned char *chunk_oid_lookup;
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const unsigned char *chunk_object_offsets;
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const unsigned char *chunk_large_offsets;
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const char **pack_names;
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struct packed_git **packs;
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char object_dir[FLEX_ARRAY];
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};
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#define MIDX_PROGRESS (1 << 0)
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char *get_midx_rev_filename(struct multi_pack_index *m);
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struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local);
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int prepare_midx_pack(struct repository *r, struct multi_pack_index *m, uint32_t pack_int_id);
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int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result);
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off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos);
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uint32_t nth_midxed_pack_int_id(struct multi_pack_index *m, uint32_t pos);
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struct object_id *nth_midxed_object_oid(struct object_id *oid,
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struct multi_pack_index *m,
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uint32_t n);
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int fill_midx_entry(struct repository *r, const struct object_id *oid, struct pack_entry *e, struct multi_pack_index *m);
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int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name);
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int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, int local);
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int write_midx_file(const char *object_dir, const char *preferred_pack_name, unsigned flags);
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void clear_midx_file(struct repository *r);
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int verify_midx_file(struct repository *r, const char *object_dir, unsigned flags);
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int expire_midx_packs(struct repository *r, const char *object_dir, unsigned flags);
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int midx_repack(struct repository *r, const char *object_dir, size_t batch_size, unsigned flags);
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void close_midx(struct multi_pack_index *m);
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#endif
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