view mercurial/cffi/bdiffbuild.py @ 34306:bd50aa1aa035

alias: make alias command lazily resolved

With many aliases, resolving them could have some visible overhead. Below is
part of traceprof [1] output of `hg bookmark --hidden`:

  (time unit: ms)
  37  \ addaliases                             dispatch.py:526
  37   | __init__ (60 times)                   dispatch.py:402
  33   | findcmd (108 times)                   cmdutil.py:721
  16   | findpossible (49 times)               cmdutil.py:683

It may get better by optimizing `findcmd` to do a bisect, but we don't
really need to resolve an alias if it's not used, so let's make those
command entries lazy.

After this patch, `addalias` takes less than 1ms.

.. perf:: improved performance when many aliases are defined

[1]: https://bitbucket.org/facebook/hg-experimental/src/9aca0dbdbdfc48457e5d2581ca2d6e662fced2e6/hgext3rd/traceprof.pyx

Differential Revision: https://phab.mercurial-scm.org/D805

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()