mercurial/cffi/mpatchbuild.py

branchcache: add attributes to track which nodes are verified

Half of the cost of loading branchcache comes from verifiying all the nodes it
has. We don't need to verify all the nodes in all the cases. Sometimes we need
to verify only a set of nodes for a set of branches. We can ignore nodes of
other branches as we are not going to read them.

This patch introduces two attributes to branchcache class. _verifiedbranches is
a set which will tell the branches for which it's head nodes are verified.
_closedverified is a boolean which will tell whether all closednodes are
verified or not.

Another idea which I had was to keep a set of nodes which are verified, but it
will be more ugly and difficult to track things on node level.

Differential Revision: https://phab.mercurial-scm.org/D6156

from __future__ import absolute_import

import cffi
import os

ffi = cffi.FFI()
mpatch_c = os.path.join(os.path.join(os.path.dirname(__file__), '..',
                                     'mpatch.c'))
with open(mpatch_c) as f:
    ffi.set_source("mercurial.cffi._mpatch", f.read(),
                   include_dirs=["mercurial"])
ffi.cdef("""

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

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

extern "Python" struct mpatch_flist* cffi_get_next_item(void*, ssize_t);

int mpatch_decode(const char *bin, ssize_t len, struct mpatch_flist** res);
ssize_t mpatch_calcsize(size_t len, struct mpatch_flist *l);
void mpatch_lfree(struct mpatch_flist *a);
static int mpatch_apply(char *buf, const char *orig, size_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);
""")

if __name__ == '__main__':
    ffi.compile()