mercurial/mpatch.h

hgweb: extract code for emitting multiple changelist records

changelistentry() exists so extensions can easily monkeypatch the
function to add additional metadata.

In at least one case at Mozilla, we have an extension doing this
where performance would greatly benefit if we were able to "batch
fetch" metadata for all revisions that will eventually have their
data set.

By extracting the logic for "obtain records for N revisions" into
a standalone function, we make it possible for a monkeypatched
function to more efficiently bulk fetch data for N revisions.

Differential Revision: https://phab.mercurial-scm.org/D3573

#ifndef _HG_MPATCH_H_
#define _HG_MPATCH_H_

#define MPATCH_ERR_NO_MEM -3
#define MPATCH_ERR_CANNOT_BE_DECODED -2
#define MPATCH_ERR_INVALID_PATCH -1

struct mpatch_frag {
	int start, end, len;
	const char *data;
};

struct mpatch_flist {
	struct mpatch_frag *base, *head, *tail;
};

int mpatch_decode(const char *bin, ssize_t len, struct mpatch_flist **res);
ssize_t mpatch_calcsize(ssize_t len, struct mpatch_flist *l);
void mpatch_lfree(struct mpatch_flist *a);
int mpatch_apply(char *buf, const char *orig, ssize_t len,
                 struct mpatch_flist *l);
struct mpatch_flist *
mpatch_fold(void *bins, struct mpatch_flist *(*get_next_item)(void *, ssize_t),
            ssize_t start, ssize_t end);

#endif