view mercurial/cffi/bdiffbuild.py @ 35779:eefabd9ed3e1

convert: use a collections.deque

This function was doing a list.pop(0) on a list whose length
was the number of revisions to convert. Popping an early element
from long lists is not an efficient operation.

collections.deque supports efficient inserts and pops at both
ends. So we switch to that data structure.

When converting the mozilla-unified repository, which has 445,748
revisions, this change makes the "sorting..." step of
`hg convert --sourcesort` significantly faster:

before: ~59.2s
after:   ~1.3s

Differential Revision: https://phab.mercurial-scm.org/D1934

from __future__ import absolute_import

import cffi
import os

ffi = cffi.FFI()
ffi.set_source("mercurial.cffi._bdiff",
    open(os.path.join(os.path.join(os.path.dirname(__file__), '..'),
        '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()