Charles Oliver Nutter <hea...@headius.com> wrote:
> On Sun, Mar 7, 2010 at 7:12 PM, Eric Wong <normal...@yhbt.net> wrote:
> > I guess this deals with wonky multipart uploads that browsers still
> > generate these days[1]. �Ugh, yeah, it's nasty...
> > The comment below in _call is very important.
> >
> >
> > 1. �Ensure all tempfiles created by Rack go into an array in env,
> > � �probably env["rack.tempfiles"]:
> >
> > � �tempfile = Tempfile.new("foo")
> > � �(env["rack.tempfiles"] ||= []) << tempfile
>
> I'm with you so far...
>
> > 2. �Have a middleware wrap everything, including the response body:
>
> I'm a bit new to the middleware thing. Does this mean everyone would
> have to configure middleware on their setups to get this
> tempfile-closing behavior? And your comment below...does that mean
> there are situations where this wouldn't work?
>
> Closing and removing tempfiles when they're no longer needed should be
> the default behavior, not something you have to configure. It's a bug
> to not close and remove them (or at least, a bug to keep creating new
> ones and expecting GC to clean everything up eventually).I would expect major frameworks to stick this into the default
middleware stack as a convenience, but some users want a more bare-bones
Rack stack can still opt out. I see it as needless overhead as the vast
majority of HTTP requests do not create tempfiles.I don't make decisions for Rack, though.
<snip>
> > � � �# the Rack server should call this (when we're the body)
> > � � �def close
> > � � � �tempfiles = env["rack.tempfiles"]
> > � � � �if tempfiles
> > � � � � �tempfiles.each { |tmp| tmp.close! rescue nil }
> > � � � �end
> > � � �end
>
> By "the Rack server should call this" do you mean that if the server
> doesn't call this, tempfiles Rack creates will not be cleaned up until
> GC runs?Yes, a Rack-compliant server should call body.close if it responds to
body.close at the end of the response cycle for every individual
request.I put this in the wrapped body because body.each {} could be relying on
the tempfiles to generate the response. body.close is the absolute last
action for any Rack application.> Shouldn't Rack itself be guaranteeing it doesn't leave garbage files around?
>
> > � � �# wrap the normal application call, saving env
> > � � �def _call(env)
> > � � � �self.env = env
> >
> > � � � �# XXX VERY IMPORTANT:
> > � � � �# you need to ensure env stays the same throughout the request,
> > � � � �# some middlewares overwrite/replace it instead of merge!-ing into it
> > � � � �status, headers, body = app.call(env)
> > � � � �self.body = body
> > � � � �[ status, headers, self ]
> > � � �end
> > � �end
>
> Same question as above...can badly-written middleware now cause
> tempfiles to linger?Yes, it might be safer to do this before app.call above:
� env["rack.tempfiles"] ||= []
That way if env gets replaced down the stack, e.g. via:
app.call(env.merge("foo.
hello" => "world"))
# env.merge! would be correct aboveany use of env["rack.tempfiles"] will still point to the same array.
Well, almost...Then again some bad middleware could do:
� env["rack.tempfiles"] += [ tmp_a, tmp_b ]Instead of what they _should_ do:
� env["rack.tempfiles"].concat([ tmp_a, tmp_b ]) So yes, discourage future middleware authors from replacing
the rack.tempfiles array.--
Eric Wong