tags-cache: directly perform a monimal walk for hgtagsfnodescache warming We do something narrower than the path retrieving data. So lets use dedicated code instead. This provides further useful speedup: ### data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog # benchmark.name = hg.debug.debug-update-cache # bin-env-vars.hg.flavor = default # bin-env-vars.hg.py-re2-module = default # benchmark.variants.pre-state = warm before-this-series: 19.947581 skip-fnode-filter: 18.916804 (-5.17%, -1.03) use-rev-num: 17.493725 (-12.30%, -2.45) this-changesets: 15.919466 (-20.19%, -4.03)

#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