WIP: Cache restructure middleware args in HTTP endpoint macros

[frenchy64]

This is a followup to #1394 where we pushed all binding restructure middleware to the HTTP endpoint macros. It did not fix original problem of POST /bundle/import reevaluating its schema.

The HTTP endpoint macros reevaluate their arguments. This is by design, but very bad for performance. For example, the following benchmark simulates a route with a :body schema that takes 100ms (just an arbitrary round number) to evaluate/initialize. On master, 10 calls to this endpoint takes ~1030 ms. After this PR, it takes ~3ms.

(defn benchmark []
  (let [sleep (fn []
                (do (println "\tSleeping...")
                    (Thread/sleep 100)
                    (println "\tDone sleeping")))
        g (str (gensym))
        _ (println "vvvvvvvvvvvvvvvvvvvvvv")
        _ (println "Initializing route...")
        route (time
                (sut/POST "*" []
                          :body [body (do (sleep) s/Any)]
                          {:status 200
                           :body g}))
        _ (println "Done initializing route")
        _ (println "^^^^^^^^^^^^^^^^^^^^^^")]
    (println "vvvvvvvvvvvvvvvvvvvvvv")
    (println "Calling route...")
    (time
      (dotimes [i 10]
        (println "Call" i)
        (assert (= g (:body ((:handler route)
                             {:request-method :post :uri "/"}))))))
    (println "Done calling route")
    (println "^^^^^^^^^^^^^^^^^^^^^^"))
  :ok)

master bench result
Bench results for this PR included in the tests.

This PR rewrites compojure endpoint macro calls when it's safe. In particular, if the macro does not bind req like

(POST "" [] ...)

instead of

(POST "" req ...)

then we can rewrite args like

(POST "" [] :body [body SCHEMA] ...)

to

(let [s SCHEMA] (POST "" [] :body [body s] ...))

If it is not safe, then this PR throws a compile-time error and shows the user how to make the most performant endpoint. For example, if req is bound like here:

(ANY "*" req
     :body [body (->dynamic-schema)]
     {:status 200
      :body "hello"})

then the following error is thrown during expansion of ANY:

Please let-bind the :body schema like so:
(let [s# (->dynamic-schema)] (ANY "*" req :body [body s#] ...))

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§ Release Notes

intern: Cache restructure middleware args in HTTP endpoint macros

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