[PATCH STABLE] revset: add an optimised baseset.__contains__ (issue4371)

[Pierre-Yves David]

On 09/17/2014 11:00 PM, Pierre-Yves David wrote:
> # HG changeset patch
> # User Pierre-Yves David <pierre-yves.david at fb.com>
> # Date 1410937169 25200
> #      Tue Sep 16 23:59:29 2014 -0700
> # Branch stable
> # Node ID 2d35709521152e0da815f59c37daa0032704adaa
> # Parent  4bbcee186fc64e39c51f90e8256466885a3a4d65
> revset: add an optimised baseset.__contains__ (issue4371)
>
>
> The baseset class is based on a python list. This means that base.__contains__
> was absolutely as crappy as list.__contains__. We now rely on __contains__ from
> the underlying set.
>
> This will avoid having to explicitly convert the baseset to a set (using
> baseset.set()) whenever one want fast membership test.
>
> Apparently there is already code that forgot to do such conversion since we
> observe a massive speedup in some test.

The said code is `baseset.filter` that creates a `lazyset(self, 
filter)`. The lazyset then do `if x in self._subset`.

We could use self.set() there but it would cause issues with action 
related to ordering on lazyset. In any case I still believe that having 
a fast __contains__ method on all smartset is the way to go.

> revset #25: roots((0::) - (0::tip))
> 0) wall 2.079454 comb 2.080000 user 2.080000 sys 0.000000 (best of 5)
> 1) wall 0.132970 comb 0.130000 user 0.130000 sys 0.000000 (best of 65)
>
> No regression is observed in benchmarks.
>
> This change improve the issue4371 back to acceptable situation (but are still
> slower than manual substraction)
>
> diff --git a/mercurial/revset.py b/mercurial/revset.py
> --- a/mercurial/revset.py
> +++ b/mercurial/revset.py
> @@ -2226,10 +2226,14 @@ class baseset(list):
>           This is part of the mandatory API for smartset."""
>           if not self._set:
>               self._set = set(self)
>           return self._set
>
> +    @util.propertycache
> +    def __contains__(self):
> +        return self.set().__contains__
> +
>       def __sub__(self, other):
>           """Returns a new object with the substraction of the two collections.
>
>           This is part of the mandatory API for smartset."""
>           # If we are operating on 2 baseset, do the computation now since all
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-- 
Pierre-Yves David