calculators.clj

(defn wrap-middleware-logging
  ([handler middlware-name]
     (wrap-middleware-logging handler middlware-name false))
  ([handler middlware-name summarize-and-log?]
     (fn [req]
       (tap (str middleware-name "-REQUEST") request)
       (let [start (ts/now)
             result (handler req)
             end (ts/now)
             result (if (map? result) ;; safety valve for legacy middlewares
                      (update-in result
                                 [::timings]
                                 #(conj (or % [])
                                        {:middleware middlware-name
                                         :middleware-elapsed (- end start)}))
                      result)]
         (tap (str middleware-name "-RESPONSE") result)
         (if (and summarize-and-log?
                  (map? result)) ;; safety valve for legacy middlewares
           (do
             (tracing/info {:middleware-timings (::timings result)}
                           [:middleware-timings])
             (dissoc result ::timings))
           result)))))

(defn wrap-middlewares [summarizing? handler middlewares]
  (let [summarize?-determinations (conj (vec (repeat (dec (count middlewares))
                                                     false))
                                        summarizing?)
        mw-names (map str middlewares)
        logging-mws (for [[summarize? mw-name] (map list
                                                    summarize?-determinations
                                                    mw-names)]
                      `(wrap-middleware-logging ~mw-name ~summarize?))]
    `(-> ~handler
         ~@(interleave middlewares logging-mws))))

(defmacro summarizing-middleware->
  "Top-level way to log timing info for each middleware it wraps"
  [handler & middlewares]
  (wrap-middlewares true handler middlewares))

(defmacro middleware->
  "Use from within other summarizing-middleware-> calls"
  [handler & middlewares]
  (wrap-middlewares false handler middlewares))