view mercurial/mpatch.h @ 47425:e0a314bcbc9d

revlog: Extract low-level random-access file read caching logic

The `revlog` class does many things, among which fulfilling requests for
arbitrary byte slices from the revlog "data file" by reading a larger chunk
and caching it in memory, in order to reduce the number of system calls.

This extracts that logic into a new class, so that it may later also be used
for the side-data file (with another instance of that class).

The copyright notice of the new file does not include a date or author name
since such information tend not to be kept up-to-date:

https://www.linuxfoundation.org/en/blog/copyright-notices-in-open-source-software-projects/

Differential Revision: https://phab.mercurial-scm.org/D10878

#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