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Diffstat (limited to 'third_party/git/pack-objects.h')
| -rw-r--r-- | third_party/git/pack-objects.h | 451 |
1 files changed, 451 insertions, 0 deletions
diff --git a/third_party/git/pack-objects.h b/third_party/git/pack-objects.h new file mode 100644 index 000000000000..9d88e3e518f0 --- /dev/null +++ b/third_party/git/pack-objects.h @@ -0,0 +1,451 @@ +#ifndef PACK_OBJECTS_H +#define PACK_OBJECTS_H + +#include "object-store.h" +#include "thread-utils.h" +#include "pack.h" + +struct repository; + +#define DEFAULT_DELTA_CACHE_SIZE (256 * 1024 * 1024) + +#define OE_DFS_STATE_BITS 2 +#define OE_DEPTH_BITS 12 +#define OE_IN_PACK_BITS 10 +#define OE_Z_DELTA_BITS 20 +/* + * Note that oe_set_size() becomes expensive when the given size is + * above this limit. Don't lower it too much. + */ +#define OE_SIZE_BITS 31 +#define OE_DELTA_SIZE_BITS 23 + +/* + * State flags for depth-first search used for analyzing delta cycles. + * + * The depth is measured in delta-links to the base (so if A is a delta + * against B, then A has a depth of 1, and B a depth of 0). + */ +enum dfs_state { + DFS_NONE = 0, + DFS_ACTIVE, + DFS_DONE, + DFS_NUM_STATES +}; + +/* + * The size of struct nearly determines pack-objects's memory + * consumption. This struct is packed tight for that reason. When you + * add or reorder something in this struct, think a bit about this. + * + * basic object info + * ----------------- + * idx.oid is filled up before delta searching starts. idx.crc32 is + * only valid after the object is written out and will be used for + * generating the index. idx.offset will be both gradually set and + * used in writing phase (base objects get offset first, then deltas + * refer to them) + * + * "size" is the uncompressed object size. Compressed size of the raw + * data for an object in a pack is not stored anywhere but is computed + * and made available when reverse .idx is made. Note that when a + * delta is reused, "size" is the uncompressed _delta_ size, not the + * canonical one after the delta has been applied. + * + * "hash" contains a path name hash which is used for sorting the + * delta list and also during delta searching. Once prepare_pack() + * returns it's no longer needed. + * + * source pack info + * ---------------- + * The (in_pack, in_pack_offset) tuple contains the location of the + * object in the source pack. in_pack_header_size allows quickly + * skipping the header and going straight to the zlib stream. + * + * "type" and "in_pack_type" both describe object type. in_pack_type + * may contain a delta type, while type is always the canonical type. + * + * deltas + * ------ + * Delta links (delta, delta_child and delta_sibling) are created to + * reflect that delta graph from the source pack then updated or added + * during delta searching phase when we find better deltas. + * + * delta_child and delta_sibling are last needed in + * compute_write_order(). "delta" and "delta_size" must remain valid + * at object writing phase in case the delta is not cached. + * + * If a delta is cached in memory and is compressed, delta_data points + * to the data and z_delta_size contains the compressed size. If it's + * uncompressed [1], z_delta_size must be zero. delta_size is always + * the uncompressed size and must be valid even if the delta is not + * cached. + * + * [1] during try_delta phase we don't bother with compressing because + * the delta could be quickly replaced with a better one. + */ +struct object_entry { + struct pack_idx_entry idx; + void *delta_data; /* cached delta (uncompressed) */ + off_t in_pack_offset; + uint32_t hash; /* name hint hash */ + unsigned size_:OE_SIZE_BITS; + unsigned size_valid:1; + uint32_t delta_idx; /* delta base object */ + uint32_t delta_child_idx; /* deltified objects who bases me */ + uint32_t delta_sibling_idx; /* other deltified objects who + * uses the same base as me + */ + unsigned delta_size_:OE_DELTA_SIZE_BITS; /* delta data size (uncompressed) */ + unsigned delta_size_valid:1; + unsigned char in_pack_header_size; + unsigned in_pack_idx:OE_IN_PACK_BITS; /* already in pack */ + unsigned z_delta_size:OE_Z_DELTA_BITS; + unsigned type_valid:1; + unsigned no_try_delta:1; + unsigned type_:TYPE_BITS; + unsigned in_pack_type:TYPE_BITS; /* could be delta */ + + unsigned preferred_base:1; /* + * we do not pack this, but is available + * to be used as the base object to delta + * objects against. + */ + unsigned tagged:1; /* near the very tip of refs */ + unsigned filled:1; /* assigned write-order */ + unsigned dfs_state:OE_DFS_STATE_BITS; + unsigned depth:OE_DEPTH_BITS; + unsigned ext_base:1; /* delta_idx points outside packlist */ + + /* + * pahole results on 64-bit linux (gcc and clang) + * + * size: 80, bit_padding: 9 bits + * + * and on 32-bit (gcc) + * + * size: 76, bit_padding: 9 bits + */ +}; + +struct packing_data { + struct repository *repo; + struct object_entry *objects; + uint32_t nr_objects, nr_alloc; + + int32_t *index; + uint32_t index_size; + + unsigned int *in_pack_pos; + unsigned long *delta_size; + + /* + * Only one of these can be non-NULL and they have different + * sizes. if in_pack_by_idx is allocated, oe_in_pack() returns + * the pack of an object using in_pack_idx field. If not, + * in_pack[] array is used the same way as in_pack_pos[] + */ + struct packed_git **in_pack_by_idx; + struct packed_git **in_pack; + + /* + * During packing with multiple threads, protect the in-core + * object database from concurrent accesses. + */ + pthread_mutex_t odb_lock; + + /* + * This list contains entries for bases which we know the other side + * has (e.g., via reachability bitmaps), but which aren't in our + * "objects" list. + */ + struct object_entry *ext_bases; + uint32_t nr_ext, alloc_ext; + + uintmax_t oe_size_limit; + uintmax_t oe_delta_size_limit; + + /* delta islands */ + unsigned int *tree_depth; + unsigned char *layer; +}; + +void prepare_packing_data(struct repository *r, struct packing_data *pdata); + +/* Protect access to object database */ +static inline void packing_data_lock(struct packing_data *pdata) +{ + pthread_mutex_lock(&pdata->odb_lock); +} +static inline void packing_data_unlock(struct packing_data *pdata) +{ + pthread_mutex_unlock(&pdata->odb_lock); +} + +struct object_entry *packlist_alloc(struct packing_data *pdata, + const struct object_id *oid); + +struct object_entry *packlist_find(struct packing_data *pdata, + const struct object_id *oid); + +static inline uint32_t pack_name_hash(const char *name) +{ + uint32_t c, hash = 0; + + if (!name) + return 0; + + /* + * This effectively just creates a sortable number from the + * last sixteen non-whitespace characters. Last characters + * count "most", so things that end in ".c" sort together. + */ + while ((c = *name++) != 0) { + if (isspace(c)) + continue; + hash = (hash >> 2) + (c << 24); + } + return hash; +} + +static inline enum object_type oe_type(const struct object_entry *e) +{ + return e->type_valid ? e->type_ : OBJ_BAD; +} + +static inline void oe_set_type(struct object_entry *e, + enum object_type type) +{ + if (type >= OBJ_ANY) + BUG("OBJ_ANY cannot be set in pack-objects code"); + + e->type_valid = type >= OBJ_NONE; + e->type_ = (unsigned)type; +} + +static inline unsigned int oe_in_pack_pos(const struct packing_data *pack, + const struct object_entry *e) +{ + return pack->in_pack_pos[e - pack->objects]; +} + +static inline void oe_set_in_pack_pos(const struct packing_data *pack, + const struct object_entry *e, + unsigned int pos) +{ + pack->in_pack_pos[e - pack->objects] = pos; +} + +static inline struct packed_git *oe_in_pack(const struct packing_data *pack, + const struct object_entry *e) +{ + if (pack->in_pack_by_idx) + return pack->in_pack_by_idx[e->in_pack_idx]; + else + return pack->in_pack[e - pack->objects]; +} + +void oe_map_new_pack(struct packing_data *pack); + +static inline void oe_set_in_pack(struct packing_data *pack, + struct object_entry *e, + struct packed_git *p) +{ + if (pack->in_pack_by_idx) { + if (p->index) { + e->in_pack_idx = p->index; + return; + } + /* + * We're accessing packs by index, but this pack doesn't have + * an index (e.g., because it was added since we created the + * in_pack_by_idx array). Bail to oe_map_new_pack(), which + * will convert us to using the full in_pack array, and then + * fall through to our in_pack handling. + */ + oe_map_new_pack(pack); + } + pack->in_pack[e - pack->objects] = p; +} + +static inline struct object_entry *oe_delta( + const struct packing_data *pack, + const struct object_entry *e) +{ + if (!e->delta_idx) + return NULL; + if (e->ext_base) + return &pack->ext_bases[e->delta_idx - 1]; + else + return &pack->objects[e->delta_idx - 1]; +} + +static inline void oe_set_delta(struct packing_data *pack, + struct object_entry *e, + struct object_entry *delta) +{ + if (delta) + e->delta_idx = (delta - pack->objects) + 1; + else + e->delta_idx = 0; +} + +void oe_set_delta_ext(struct packing_data *pack, + struct object_entry *e, + const struct object_id *oid); + +static inline struct object_entry *oe_delta_child( + const struct packing_data *pack, + const struct object_entry *e) +{ + if (e->delta_child_idx) + return &pack->objects[e->delta_child_idx - 1]; + return NULL; +} + +static inline void oe_set_delta_child(struct packing_data *pack, + struct object_entry *e, + struct object_entry *delta) +{ + if (delta) + e->delta_child_idx = (delta - pack->objects) + 1; + else + e->delta_child_idx = 0; +} + +static inline struct object_entry *oe_delta_sibling( + const struct packing_data *pack, + const struct object_entry *e) +{ + if (e->delta_sibling_idx) + return &pack->objects[e->delta_sibling_idx - 1]; + return NULL; +} + +static inline void oe_set_delta_sibling(struct packing_data *pack, + struct object_entry *e, + struct object_entry *delta) +{ + if (delta) + e->delta_sibling_idx = (delta - pack->objects) + 1; + else + e->delta_sibling_idx = 0; +} + +unsigned long oe_get_size_slow(struct packing_data *pack, + const struct object_entry *e); +static inline unsigned long oe_size(struct packing_data *pack, + const struct object_entry *e) +{ + if (e->size_valid) + return e->size_; + + return oe_get_size_slow(pack, e); +} + +static inline int oe_size_less_than(struct packing_data *pack, + const struct object_entry *lhs, + unsigned long rhs) +{ + if (lhs->size_valid) + return lhs->size_ < rhs; + if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */ + return 0; + return oe_get_size_slow(pack, lhs) < rhs; +} + +static inline int oe_size_greater_than(struct packing_data *pack, + const struct object_entry *lhs, + unsigned long rhs) +{ + if (lhs->size_valid) + return lhs->size_ > rhs; + if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */ + return 1; + return oe_get_size_slow(pack, lhs) > rhs; +} + +static inline void oe_set_size(struct packing_data *pack, + struct object_entry *e, + unsigned long size) +{ + if (size < pack->oe_size_limit) { + e->size_ = size; + e->size_valid = 1; + } else { + e->size_valid = 0; + if (oe_get_size_slow(pack, e) != size) + BUG("'size' is supposed to be the object size!"); + } +} + +static inline unsigned long oe_delta_size(struct packing_data *pack, + const struct object_entry *e) +{ + if (e->delta_size_valid) + return e->delta_size_; + + /* + * pack->delta_size[] can't be NULL because oe_set_delta_size() + * must have been called when a new delta is saved with + * oe_set_delta(). + * If oe_delta() returns NULL (i.e. default state, which means + * delta_size_valid is also false), then the caller must never + * call oe_delta_size(). + */ + return pack->delta_size[e - pack->objects]; +} + +static inline void oe_set_delta_size(struct packing_data *pack, + struct object_entry *e, + unsigned long size) +{ + if (size < pack->oe_delta_size_limit) { + e->delta_size_ = size; + e->delta_size_valid = 1; + } else { + packing_data_lock(pack); + if (!pack->delta_size) + ALLOC_ARRAY(pack->delta_size, pack->nr_alloc); + packing_data_unlock(pack); + + pack->delta_size[e - pack->objects] = size; + e->delta_size_valid = 0; + } +} + +static inline unsigned int oe_tree_depth(struct packing_data *pack, + struct object_entry *e) +{ + if (!pack->tree_depth) + return 0; + return pack->tree_depth[e - pack->objects]; +} + +static inline void oe_set_tree_depth(struct packing_data *pack, + struct object_entry *e, + unsigned int tree_depth) +{ + if (!pack->tree_depth) + CALLOC_ARRAY(pack->tree_depth, pack->nr_alloc); + pack->tree_depth[e - pack->objects] = tree_depth; +} + +static inline unsigned char oe_layer(struct packing_data *pack, + struct object_entry *e) +{ + if (!pack->layer) + return 0; + return pack->layer[e - pack->objects]; +} + +static inline void oe_set_layer(struct packing_data *pack, + struct object_entry *e, + unsigned char layer) +{ + if (!pack->layer) + CALLOC_ARRAY(pack->layer, pack->nr_alloc); + pack->layer[e - pack->objects] = layer; +} + +#endif |