git/diffcore.h
Jeff King a5a3878ba7 diffcore-rename: cache file deltas
We find rename candidates by computing a fingerprint hash of
each file, and then comparing those fingerprints. There are
inherently O(n^2) comparisons, so it pays in CPU time to
hoist the (rather expensive) computation of the fingerprint
out of that loop (or to cache it once we have computed it once).

Previously, we didn't keep the filespec information around
because then we had the potential to consume a great deal of
memory. However, instead of keeping all of the filespec
data, we can instead just keep the fingerprint.

This patch implements and uses diff_free_filespec_data_large
to accomplish that goal. We also have to change
estimate_similarity not to needlessly repopulate the
filespec data when we already have the hash.

Practical tests showed 4.5x speedup for a 10% memory usage
increase.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-09-26 00:40:32 -07:00

120 lines
3.9 KiB
C

/*
* Copyright (C) 2005 Junio C Hamano
*/
#ifndef DIFFCORE_H
#define DIFFCORE_H
/* This header file is internal between diff.c and its diff transformers
* (e.g. diffcore-rename, diffcore-pickaxe). Never include this header
* in anything else.
*/
/* We internally use unsigned short as the score value,
* and rely on an int capable to hold 32-bits. -B can take
* -Bmerge_score/break_score format and the two scores are
* passed around in one int (high 16-bit for merge and low 16-bit
* for break).
*/
#define MAX_SCORE 60000.0
#define DEFAULT_RENAME_SCORE 30000 /* rename/copy similarity minimum (50%) */
#define DEFAULT_BREAK_SCORE 30000 /* minimum for break to happen (50%) */
#define DEFAULT_MERGE_SCORE 36000 /* maximum for break-merge to happen 60%) */
#define MINIMUM_BREAK_SIZE 400 /* do not break a file smaller than this */
struct diff_filespec {
unsigned char sha1[20];
char *path;
void *data;
void *cnt_data;
const char *funcname_pattern_ident;
unsigned long size;
int xfrm_flags; /* for use by the xfrm */
unsigned short mode; /* file mode */
unsigned sha1_valid : 1; /* if true, use sha1 and trust mode;
* if false, use the name and read from
* the filesystem.
*/
#define DIFF_FILE_VALID(spec) (((spec)->mode) != 0)
unsigned should_free : 1; /* data should be free()'ed */
unsigned should_munmap : 1; /* data should be munmap()'ed */
unsigned checked_attr : 1;
unsigned is_binary : 1; /* data should be considered "binary" */
};
extern struct diff_filespec *alloc_filespec(const char *);
extern void fill_filespec(struct diff_filespec *, const unsigned char *,
unsigned short);
extern int diff_populate_filespec(struct diff_filespec *, int);
extern void diff_free_filespec_data(struct diff_filespec *);
extern void diff_free_filespec_data_large(struct diff_filespec *);
extern int diff_filespec_is_binary(struct diff_filespec *);
struct diff_filepair {
struct diff_filespec *one;
struct diff_filespec *two;
unsigned short int score;
char status; /* M C R N D U (see Documentation/diff-format.txt) */
unsigned source_stays : 1; /* all of R/C are copies */
unsigned broken_pair : 1;
unsigned renamed_pair : 1;
unsigned is_unmerged : 1;
};
#define DIFF_PAIR_UNMERGED(p) ((p)->is_unmerged)
#define DIFF_PAIR_RENAME(p) ((p)->renamed_pair)
#define DIFF_PAIR_BROKEN(p) \
( (!DIFF_FILE_VALID((p)->one) != !DIFF_FILE_VALID((p)->two)) && \
((p)->broken_pair != 0) )
#define DIFF_PAIR_TYPE_CHANGED(p) \
((S_IFMT & (p)->one->mode) != (S_IFMT & (p)->two->mode))
#define DIFF_PAIR_MODE_CHANGED(p) ((p)->one->mode != (p)->two->mode)
extern void diff_free_filepair(struct diff_filepair *);
extern int diff_unmodified_pair(struct diff_filepair *);
struct diff_queue_struct {
struct diff_filepair **queue;
int alloc;
int nr;
};
extern struct diff_queue_struct diff_queued_diff;
extern struct diff_filepair *diff_queue(struct diff_queue_struct *,
struct diff_filespec *,
struct diff_filespec *);
extern void diff_q(struct diff_queue_struct *, struct diff_filepair *);
extern void diffcore_pathspec(const char **pathspec);
extern void diffcore_break(int);
extern void diffcore_rename(struct diff_options *);
extern void diffcore_merge_broken(void);
extern void diffcore_pickaxe(const char *needle, int opts);
extern void diffcore_order(const char *orderfile);
#define DIFF_DEBUG 0
#if DIFF_DEBUG
void diff_debug_filespec(struct diff_filespec *, int, const char *);
void diff_debug_filepair(const struct diff_filepair *, int);
void diff_debug_queue(const char *, struct diff_queue_struct *);
#else
#define diff_debug_filespec(a,b,c) do {} while(0)
#define diff_debug_filepair(a,b) do {} while(0)
#define diff_debug_queue(a,b) do {} while(0)
#endif
extern int diffcore_count_changes(struct diff_filespec *src,
struct diff_filespec *dst,
void **src_count_p,
void **dst_count_p,
unsigned long delta_limit,
unsigned long *src_copied,
unsigned long *literal_added);
#endif