setup_bdiff_cffi.py

templater: use unfiltered changelog to calculate shortest() at constant time

cl._partialmatch() can be pretty slow if hidden revisions are involved. This
patch cancels the slowdown introduced by the previous patch by using an
unfiltered changelog, which means shortest(node) isn't always the shortest.

The result isn't perfect, but seems okay as long as shortest(node) is short
enough to type and can be used as an identifier.

  (with hidden revisions)
  % hg log -R hg-committed -r0:20000 -T '{node|shortest}\n' --time > /dev/null
  (.^^) time: real 1.530 secs (user 1.480+0.000 sys 0.040+0.000)
  (.^)  time: real 43.080 secs (user 43.060+0.000 sys 0.030+0.000)
  (.)   time: real 1.680 secs (user 1.650+0.000 sys 0.020+0.000)

from __future__ import absolute_import

import cffi
import os

ffi = cffi.FFI()
ffi.set_source("_bdiff_cffi",
    open(os.path.join(os.path.join(os.path.dirname(__file__), 'mercurial'),
        'bdiff.c')).read(), include_dirs=['mercurial'])
ffi.cdef("""
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);
void free(void*);
""")

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