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git/pack-objects.h

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#ifndef PACK_OBJECTS_H
#define PACK_OBJECTS_H
#include "object-store.h"
#include "thread-utils.h"
#include "pack.h"
#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 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;
pthread_mutex_t 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 packing_data *pdata);
static inline void packing_data_lock(struct packing_data *pdata)
{
pthread_mutex_lock(&pdata->lock);
}
static inline void packing_data_unlock(struct packing_data *pdata)
{
pthread_mutex_unlock(&pdata->lock);
}
struct object_entry *packlist_alloc(struct packing_data *pdata,
const unsigned char *sha1,
uint32_t index_pos);
struct object_entry *packlist_find(struct packing_data *pdata,
const unsigned char *sha1,
uint32_t *index_pos);
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,
struct packed_git *p);
static inline void oe_set_in_pack(struct packing_data *pack,
struct object_entry *e,
struct packed_git *p)
{
if (!p->index)
oe_map_new_pack(pack, p);
if (pack->in_pack_by_idx)
e->in_pack_idx = p->index;
else
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 unsigned char *sha1);
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
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