[MERGE] is_ignored improvements...

[Jan Hudec]

On Thu, May 18, 2006 at 11:21:17 -0500, John Arbash Meinel wrote:
> Did you try performance testing with and without group matching? I would
> have guessed that it was faster to match without the groups.
> The reason I originally preferred Jan's double api, is because *most* of
> the callers of is_ignored() didn't actually care about what pattern was
> matched. So why spend the time if you are just throwing the information
> away.
> 
> Remember, status also uses 'is_ignored', and that is actually where *I*
> ran into the major slowdown. (add, status, ignored, info all use it)
> 
> If you do grep "\<is_ignored\>", you get:
> add.py:158:                    ignore_glob = tree.is_ignored(subp)
> builtins.py:1425:            pat = tree.is_ignored(path)
> info.py:203:        if working.is_ignored(path):
> tree.py:242:        if new_tree.is_ignored(filename):
> workingtree.py:672:        elif self.is_ignored(filename):
> workingtree.py:710:                elif self.is_ignored(fp):
> workingtree.py:889:            if not self.is_ignored(subp):
> workingtree.py:973:            pat = self.is_ignored(subp)
> workingtree.py:994:    def is_ignored(self, filename):
> workingtree.py:1160:                if self.is_ignored(f):
> 
> Out of these requests 3 use the return value, and 6 just check for
> true/false.

... so I just tried a simple, not at all representative test. I took patterns
  ['.*\\.%i' % i for i in range(0, 999) and matched them:
1. Non-capturing groups, all at once.
2. Non-capturing groups, 50 at a time, until match is found.
3. Capturing groups, 50 at a time, until match is found.
4. No groups, each separately, until match is found.
against a pattern corresponding to 789th group ('foo.789'). And the times for
100000 runs on my machine (Athlon64 3000 (2.2GHz)) were about:
1. 12.5
2. 13.7
3. 18.9
4. 70.3

So the groups slows it down by about a half, but compared to matching one
pattern at a time it's not /that/ significant.

Now I have to say, that when I doubled the pattern legnth and matched against
'foo.1789', the times doubled even for the single pattern. That means that
the pattern compiler does not compile to a DFA. So it will be N^2 in all
cases until python gets a better regex compiler.

-- 
						 Jan 'Bulb' Hudec <bulb at ucw.cz>
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