Protect appenders from delay replacement through middleware

- This simplifies the requirements for appender authors.
  - Note that middleware authors still need to be careful since
    it'd be infeasible to offer similar protection between each
    individual layer of middleware.

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Pending
 
 * **New**: added 3rd-party gelf appender [#147 @davewo]
+* **Implementation**: appenders no longer need to worry about using `force` instead of `@`/`deref`
 
 
 

src/taoensso/timbre.cljx

@@ -38,13 +38,13 @@
   ([{:keys [no-stacktrace? stacktrace-fonts] :as opts} data]
    (let [{:keys [level ?err_ vargs_ msg_ ?ns-str hostname_ timestamp_]} data]
      (str
-       #+clj (force timestamp_) #+clj " "
+       #+clj @timestamp_ #+clj " "
-       #+clj (force hostname_)  #+clj " "
+       #+clj @hostname_  #+clj " "
        (str/upper-case (name level))  " "
        "[" (or ?ns-str "?ns") "] - "
-       (force msg_)
+       @msg_
        (when-not no-stacktrace?
-         (when-let [err (force ?err_)]
+         (when-let [err @?err_]
            (str "\n" (stacktrace err opts))))))))
 
 ;;; Alias core appenders here for user convenience
@@ -251,7 +251,7 @@
   rate-limiting purposes, etc."
   [data]
   (let [{:keys [?ns-str ?line vargs_]} data
-        vargs (force vargs_)]
+        vargs @vargs_]
     (str
       (or (some #(and (map? %) (:timbre/hash %)) vargs) ; Explicit hash given
           #_[?ns-str ?line] ; TODO Waiting on http://goo.gl/cVVAYA
@@ -330,7 +330,7 @@
   [config level ?ns-str ?file ?line msg-type vargs_ ?base-data]
   (when (log? level ?ns-str config)
     (let [instant (enc/now-dt)
-          vargs*_ (delay (vsplit-err1 (force vargs_)))
+          vargs*_ (delay (vsplit-err1 @vargs_))
           ?err_   (delay (get @vargs*_ 0))
           vargs_  (delay (get @vargs*_ 1))
           context *context*
@@ -352,7 +352,7 @@
           msg-fn
           (fn [vargs_] ; For use *after* middleware, etc.
             (when-not (nil? msg-type)
-              (when-let [vargs (have [:or nil? vector?] (force vargs_))]
+              (when-let [vargs (have [:or nil? vector?] @vargs_)]
                 (case msg-type
                   :p (str-join vargs)
                   :f (let [[fmt args] (enc/vsplit-first vargs)]
@@ -373,7 +373,15 @@
             (when (and (:enabled? appender)
                        (level>= level (or (:min-level appender) :trace)))
 
-              (let [rate-limit-specs (:rate-limit appender)
+              (let [;; As a convenience to appenders, make sure that middleware
+                    ;; hasn't replaced any delays with non-delays
+                    data
+                    (merge data
+                      {:?err_                 (->delay (:?err_     data))
+                       :vargs_                (->delay (:vargs_    data))
+                       #+clj :hostname_ #+clj (->delay (:hostname_ data))})
+
+                    rate-limit-specs (:rate-limit appender)
                     data-hash-fn (inherit-over :data-hash-fn appender config
                                    default-data-hash-fn)
                     rate-limit-okay?

src/taoensso/timbre/appenders/3rd_party/android_logcat.clj

@@ -20,9 +20,9 @@
    (fn [data]
      (let [{:keys [level timestamp_ msg_]} data]
        (str
-         (force timestamp_) " "
+         @timestamp_ " "
          (str/upper-case (name level))  " "
-         (force msg_))))
+         @msg_)))
 
    :fn
    (fn [data]
@@ -30,7 +30,7 @@
            ns         (str ?ns-str "")
            output-str (output-fn data)]
 
-       (if-let [throwable (force ?err_)]
+       (if-let [throwable @?err_]
          (case level
            :trace  (android.util.Log/d ns output-str throwable)
            :debug  (android.util.Log/d ns output-str throwable)

src/taoensso/timbre/appenders/3rd_party/congomongo.clj

@@ -22,9 +22,9 @@
   (let [entry {:instant  instant
                :level    level
                :?ns-str  (str  (:?ns-str       data))
-               :hostname (str (force (:hostname_     data)))
+               :hostname (str @(:hostname_     data))
-               :vargs    (str (force (:vargs_        data)))
+               :vargs    (str @(:vargs_        data))
-               :?err     (str (force (:?err_         data)))}]
+               :?err     (str @(:?err_         data))}]
     (mongo/with-mongo (ensure-conn config)
       (mongo/insert! collection entry))))
 

src/taoensso/timbre/appenders/3rd_party/gelf.clj

@@ -52,6 +52,6 @@
         (let [{:keys [appender msg_ level hostname_]} data
               gelf-transport (:gelf-transport appender)
               log-level      (timbre-to-gelf-level level)
-              gelf-message   (-> (GelfMessageBuilder. (force msg_) (force hostname_))
+              gelf-message   (-> (GelfMessageBuilder. @msg_ @hostname_)
                                  (.level log-level) .build)]
           (.send gelf-transport gelf-message)))})))

src/taoensso/timbre/appenders/3rd_party/irclj.clj

@@ -46,8 +46,8 @@
        (let [{:keys [level ?err_ msg_]}]
          (format "[%s] %s%s"
            (-> level name (str/upper-case))
-           (or (force msg_) "")
+           (or @msg_ "")
-           (if-let [err (force ?err_)]
+           (if-let [err @?err_]
              (str "\n" (timbre/stacktrace err))
              ""))))
 

src/taoensso/timbre/appenders/carmine.clj

@@ -58,9 +58,9 @@
                         {:instant instant
                          :level   level
                          :?ns-str   (:?ns-str       data)
-                         :hostname (force (:hostname_     data))
+                         :hostname @(:hostname_     data)
-                         :vargs    (force (:vargs_        data))
+                         :vargs    @(:vargs_        data)
-                         :?err     (force (:?err_         data))}
+                         :?err     @(:?err_         data)}
                         (when-let [pstats (:profile-stats data)]
                           {:profile-stats pstats}))
 

src/taoensso/timbre/appenders/core.cljx

@@ -41,9 +41,8 @@
                    ]}
            data
 
-           ;;; Use `force` to realise possibly-delayed args:
+           ?err  @?err_  ; ?err non-nil iff first given arg was an error
-           ?err  (force ?err_)  ; ?err non-nil iff first given arg was an error
+           vargs @vargs_ ; Vector of raw args (excl. possible first error)
-           vargs (force vargs_) ; Vector of raw args (excl. possible first error)
 
            ;; You'll often want an output string with ns, timestamp, vargs, etc.
            ;; A (fn [data]) -> string formatter is provided under the :output-fn
@@ -153,7 +152,7 @@
        :fn
        (fn [data]
          (let [{:keys [level output-fn vargs_]} data
-               vargs      (force vargs_)
+               vargs      @vargs_
                [v1 vnext] (enc/vsplit-first vargs)
                output     (if (= v1 :timbre/raw)
                             (into-array vnext)