Revision 7146e66f0861c720f9b32dc9d80ab80495a33e43 authored by Kirill Smelkov on 06 February 2014, 11:36:31 UTC, committed by Junio C Hamano on 24 February 2014, 22:43:29 UTC
This continues 4651ece8 (Switch over tree descriptors to contain a pre-parsed entry) and moves the only rest computational part mode = canon_mode(mode) from tree_entry_extract() to tree entry decode phase - to decode_tree_entry(). The reason to do it, is that canon_mode() is at least 2 conditional jumps for regular files, and that could be noticeable should canon_mode() be invoked several times. That does not matter for current Git codebase, where typical tree traversal is while (t->size) { sha1 = tree_entry_extract(t, &path, &mode); ... update_tree_entry(t); } i.e. we do t -> sha1,path.mode "extraction" only once per entry. In such cases, it does not matter performance-wise, where that mode canonicalization is done - either once in tree_entry_extract(), or once in decode_tree_entry() called by update_tree_entry() - it is approximately the same. But for future code, which could need to work with several tree_desc's in parallel, it could be handy to operate on tree_desc descriptors, and do "extracts" only when needed, or at all, access only relevant part of it through structure fields directly. And for such situations, having canon_mode() be done once in decode phase is better - we won't need to pay the performance price of 2 extra conditional jumps on every t->mode access. So let's move mode canonicalization to decode_tree_entry(). That was the final bit. Now after tree entry is decoded, it is fully ready and could be accessed either directly via field, or through tree_entry_extract() which this time got really "totally trivial". Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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pack.h
#ifndef PACK_H
#define PACK_H
#include "object.h"
#include "csum-file.h"
/*
* Packed object header
*/
#define PACK_SIGNATURE 0x5041434b /* "PACK" */
#define PACK_VERSION 2
#define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3))
struct pack_header {
uint32_t hdr_signature;
uint32_t hdr_version;
uint32_t hdr_entries;
};
/*
* The first four bytes of index formats later than version 1 should
* start with this signature, as all older git binaries would find this
* value illegal and abort reading the file.
*
* This is the case because the number of objects in a packfile
* cannot exceed 1,431,660,000 as every object would need at least
* 3 bytes of data and the overall packfile cannot exceed 4 GiB with
* version 1 of the index file due to the offsets limited to 32 bits.
* Clearly the signature exceeds this maximum.
*
* Very old git binaries will also compare the first 4 bytes to the
* next 4 bytes in the index and abort with a "non-monotonic index"
* error if the second 4 byte word is smaller than the first 4
* byte word. This would be true in the proposed future index
* format as idx_signature would be greater than idx_version.
*/
#define PACK_IDX_SIGNATURE 0xff744f63 /* "\377tOc" */
struct pack_idx_option {
unsigned flags;
/* flag bits */
#define WRITE_IDX_VERIFY 01 /* verify only, do not write the idx file */
#define WRITE_IDX_STRICT 02
uint32_t version;
uint32_t off32_limit;
/*
* List of offsets that would fit within off32_limit but
* need to be written out as 64-bit entity for byte-for-byte
* verification.
*/
int anomaly_alloc, anomaly_nr;
uint32_t *anomaly;
};
extern void reset_pack_idx_option(struct pack_idx_option *);
/*
* Packed object index header
*/
struct pack_idx_header {
uint32_t idx_signature;
uint32_t idx_version;
};
/*
* Common part of object structure used for write_idx_file
*/
struct pack_idx_entry {
unsigned char sha1[20];
uint32_t crc32;
off_t offset;
};
struct progress;
typedef int (*verify_fn)(const unsigned char*, enum object_type, unsigned long, void*, int*);
extern const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects, int nr_objects, const struct pack_idx_option *, const unsigned char *sha1);
extern int check_pack_crc(struct packed_git *p, struct pack_window **w_curs, off_t offset, off_t len, unsigned int nr);
extern int verify_pack_index(struct packed_git *);
extern int verify_pack(struct packed_git *, verify_fn fn, struct progress *, uint32_t);
extern off_t write_pack_header(struct sha1file *f, uint32_t);
extern void fixup_pack_header_footer(int, unsigned char *, const char *, uint32_t, unsigned char *, off_t);
extern char *index_pack_lockfile(int fd);
extern int encode_in_pack_object_header(enum object_type, uintmax_t, unsigned char *);
#define PH_ERROR_EOF (-1)
#define PH_ERROR_PACK_SIGNATURE (-2)
#define PH_ERROR_PROTOCOL (-3)
extern int read_pack_header(int fd, struct pack_header *);
extern struct sha1file *create_tmp_packfile(char **pack_tmp_name);
extern void finish_tmp_packfile(char *name_buffer, const char *pack_tmp_name, struct pack_idx_entry **written_list, uint32_t nr_written, struct pack_idx_option *pack_idx_opts, unsigned char sha1[]);
#endif
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