[PATCH] hg: always create new localrepository instance

[Augie Fackler]

On Sat, Sep 12, 2015 at 11:33:54AM -0700, Gregory Szorc wrote:
> # HG changeset patch
> # User Gregory Szorc <gregory.szorc at gmail.com>
> # Date 1442082716 25200
> #      Sat Sep 12 11:31:56 2015 -0700
> # Node ID ca4473ede18b892c9b15779829461735a3be8c49
> # Parent  efebefe162e98aa79438daaea9aaee47c7de33bb
> hg: always create new localrepository instance

queued, many thanks for tackling this refactoring

>
> cachedlocalrepo.copy() didn't actually create new localrepository
> instances. This meant that the new thread isolation code in hgweb wasn't
> actually using separate localrepository instances, even though it was
> properly using separate cachedlocalrepo instances.
>
> Because the behavior of the API changed, the single caller in hgweb had
> to be refactored to always call _webifyrepo() or it may not have used
> the proper filter.
>
> I confirmed via print() debugging that id(repo) is in fact different on
> each thread. This was not the case before.
>
> For reasons I can't yet explain, this does not fix issue4756. I suspect
> there is shared cache somewhere that isn't thread safe.
>
> diff --git a/mercurial/hg.py b/mercurial/hg.py
> --- a/mercurial/hg.py
> +++ b/mercurial/hg.py
> @@ -886,9 +886,14 @@ class cachedlocalrepo(object):
>
>          return tuple(state), maxmtime
>
>      def copy(self):
> -        """Obtain a copy of this class instance."""
> -        c = cachedlocalrepo(self._repo)
> +        """Obtain a copy of this class instance.
> +
> +        A new localrepository instance is obtained. The new instance should be
> +        completely independent of the original.
> +        """
> +        repo = repository(self._repo.baseui, self._repo.origroot)
> +        c = cachedlocalrepo(repo)
>          c._state = self._state
>          c.mtime = self.mtime
>          return c
> diff --git a/mercurial/hgweb/hgweb_mod.py b/mercurial/hgweb/hgweb_mod.py
> --- a/mercurial/hgweb/hgweb_mod.py
> +++ b/mercurial/hgweb/hgweb_mod.py
> @@ -234,13 +234,13 @@ class hgweb(object):
>          """
>          if self._repos:
>              cached = self._repos.pop()
>              r, created = cached.fetch()
> -            if created:
> -                r = self._webifyrepo(r)
>          else:
>              cached = self._lastrepo.copy()
>              r, created = cached.fetch()
> +        if created:
> +            r = self._webifyrepo(r)
>
>          self._lastrepo = cached
>          self.mtime = cached.mtime
>          try:
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