view mercurial/bdiff.h @ 39594:bdb41eaa8b59

snapshot: fix line order when skipping over empty deltas

The code movement in 37957e07138c introduced an error.

Since 8f83a953dddf, we discarded some revisions because they are identical to
their delta base (and use that delta base instead). That logic is good,
however, in 37957e07138c we mixed up the order of two line, adding the "new"
revision to the set of already tested one, instead of the discarded one. So in
practice, we were never investigating any revisions in a chain starting with
an empty delta. Creating significantly worst delta chain (eg: Mercurial's
manifest move goes from about 60MB up to about 80MB).

#ifndef _HG_BDIFF_H_
#define _HG_BDIFF_H_

#include "compat.h"

struct bdiff_line {
	int hash, n, e;
	ssize_t len;
	const char *l;
};

struct bdiff_hunk;
struct bdiff_hunk {
	int a1, a2, b1, b2;
	struct bdiff_hunk *next;
};

int bdiff_splitlines(const char *a, ssize_t len, struct bdiff_line **lr);
int bdiff_diff(struct bdiff_line *a, int an, struct bdiff_line *b, int bn,
               struct bdiff_hunk *base);
void bdiff_freehunks(struct bdiff_hunk *l);

#endif