tests/readlink.py

changelog: lazily parse description

Before, the description field was converted to a localstr at parse
time. With this patch, we store the raw description and convert to
a localstr when it is first accessed.

We see a revset speedup for revsets that don't access the description:

author(mpm)
0.896565
0.914234
0.869085

date(2015)
0.878797
0.891980
0.862525

extra(rebase_source)
0.865446
0.912514
0.871500

author(mpm) or author(greg)
1.801832
1.860402
1.791589

date(2015) or branch(default)
0.968276
0.994673
0.974027

author(mpm) or desc(bug) or date(2015) or extra(rebase_source)
3.656193
3.721032
3.643593

As you can see, most of these revsets are already faster than from
before this refactoring: we have already offset the performance
loss from the introduction of the new class representing parsed
changelog entries!

#!/usr/bin/env python

import errno, os, sys

for f in sys.argv[1:]:
    try:
        print f, '->', os.readlink(f)
    except OSError as err:
        if err.errno != errno.EINVAL:
            raise
        print f, 'not a symlink'

sys.exit(0)