[PATCH 3 of 3 RFC] chgserve: preimport enabled extensions

[Yuya Nishihara]

On Mon, 3 Oct 2016 07:11:20 +0100, Jun Wu wrote:
> # HG changeset patch
> # User Jun Wu <quark at fb.com>
> # Date 1475463449 -3600
> #      Mon Oct 03 03:57:29 2016 +0100
> # Node ID 6f38a7d259add12c44040535681c4b3ceef0a791
> # Parent  7d106c3386e17746c9b49ab9c788535634b3e8f6
> # Available At https://bitbucket.org/quark-zju/hg-draft
> #              hg pull https://bitbucket.org/quark-zju/hg-draft -r 6f38a7d259ad
> chgserve: preimport enabled extensions
> 
> This patch pre-imports enabled extensions, so performance improvement is
> visible. It's about 0.01 seconds slower than the old chg, which seems to be
> acceptable.

(I haven't read the patch 1 and 2 yet.)

Regarding this, I was thinking about 'extensions.<name>:enabled' syntax so
users (or sysadmins) can define a set of conditionally-enabled extensions
globally.

  [extensions]
  rebase =
  topic = /path/to/topic.py
  topic:enabled = False

chg daemon will import all extensions listed in ~/.hgrc. And if :enabled = True
is flagged by repo/.hg/hgrc, ui/reposetup() will be run.

> +def _importext(orig, name, path=None, reportfunc=None):
> +    mod = _preimported.get((name, path))
> +    if mod:
> +        return mod
> +    else:
> +        return orig(name, path, reportfunc)
> +
> +def _preimportextensions(ui):
> +    for name, path in ui.configitems("extensions"):
> +        # only enabled extensions are pre-imported - assuming importing an
> +        # extension is side-effect free.
> +        if path.startswith('!'):
> +            continue
> +        try:
> +            mod = extensions._importext(name, path)
> +        except ImportError:
> +            pass
> +        else:
> +            _preimported[(name, path)] = mod

Perhaps path needs to be normalized.