[SERVER-621] Fully construct ring handler before registering with the web
server Created: 2015/05/12 Updated: 2016/01/19 Resolved: 2015/07/23
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Puppet Server
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None
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Remaining
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Improvement
Jeremy Barlow
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customfield_10700 true
Server- TBD tickets
Puppet Server
Erik Dasher
Reviewed
SERVER 2.x, SERVER 1.x
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Description
In Puppet Server code, I noticed that we do this in master_service.clj...
(add-ring-handler this
(compojure/context path [] (core/build-ring-handler handlerequest))
{:route-id :master-routes})
... where build-ring-handler returns "compojure/routes" wrapped with middleware as
desired. I haven't really looked into what the compojure macros expand into but it seems like it
might be more efficient to do this...
(let [handler (compojure/context path []
(core/build-ring-handler handle-request))
{:route-id :master-routes})]
(add-ring-handler this handler)
...so that the logic in build-ring-handler is executed only once - not for every web request
that is handled.
Note that the same approach is currently being used for the certificate-authority-service
route registration.
Maybe there was a reason we did it this way to begin with - or maybe the overhead involved in
re-executing build-ring-handler beyond the first call isn't significant (given compilation to
byte code on the first pass, etc.).
Throwing this ticket to consider making the suggested change above as an optimization at some
point if it makes sense.
Comments
Comment by Kevin Corcoran [ 2015/07/23 ]
Jeremy Barlow - Is this ticket still relevant now that we've switched to comidi?
Comment by Jeremy Barlow [ 2015/07/23 ]
Kevin Corcoran I don't think this is relevant anymore. For the master-service, we ended up
switching to the approach of constructing the handler and just passing a reference to the handler
var in the call to add-ring-handler anyway. I think we did that around the time we were doing
some refactoring related to the legacy-routes-service. Justin May might recall more details
there.
For the certificate-authority-service, though, we're still using the approach of defining
the handler in line as part of the call to add-ring-handler. From
https://github.com/puppetlabs/puppet-server/blob/puppet-server2.1.1/src/clj/puppetlabs/services/ca/certificate_authority_service.clj#L20-L25:
(add-ring-handler
this
(-> (core/web-routes settings)
(#(comidi/context path %))
comidi/routes->handler
(core/wrap-middleware puppet-version))))
I instrumented behind each of the threaded calls made to create the handler result and confirmed
that they are each only made once - and not once per request handled like we were getting with
our compojure / ring-handler creation earlier.
So I'm good with just closing this issue out.
Comment by Kevin Corcoran [ 2015/07/23 ]
cool, thanks man.
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