Merge pull request #45 from megayu/daily

Daily rolling file appender (megayu)

src/taoensso/timbre/appenders/rolling.clj

@@ -0,0 +1,71 @@
+(ns taoensso.timbre.appenders.rolling "Rolling file appender."
+  (:require [clojure.java.io :as io]
+            [taoensso.timbre :as timbre])
+  (:import [java.text SimpleDateFormat]
+           [java.util Calendar]))
+
+(defn- rename-old-create-new-log [log old-log]
+  (.renameTo log old-log)
+  (.createNewFile log))
+
+(defn- shift-log-period [log path prev-cal]
+  (let [postfix (-> "yyyyMMdd" SimpleDateFormat. (.format (.getTime prev-cal)))
+        old-path (format "%s.%s" path postfix)
+        old-log (io/file old-path)]
+    (if (.exists old-log)
+      (loop [index 0]
+        (let [index-path (format "%s.%d" old-path index)
+              index-log (io/file index-path)]
+          (if (.exists index-log)
+            (recur (+ index 1))
+            (rename-old-create-new-log log index-log))))
+      (rename-old-create-new-log log old-log))))
+
+(defn- log-cal [date]
+  (let [now (Calendar/getInstance)]
+    (.setTime now date)
+    now))
+
+(defn- prev-period-end-cal [date pattern]
+  (let [cal (log-cal date)
+        offset (case pattern
+                 :daily 1
+                 :weekly (.get cal Calendar/DAY_OF_WEEK)
+                 :monthly (.get cal Calendar/DAY_OF_MONTH)
+                 0)]
+    (.add cal Calendar/DAY_OF_MONTH (* -1 offset))
+    (.set cal Calendar/HOUR_OF_DAY 23)
+    (.set cal Calendar/MINUTE 59)
+    (.set cal Calendar/SECOND 59)
+    (.set cal Calendar/MILLISECOND 999)
+    cal))
+
+(defn- appender-fn [{:keys [ap-config output instant]}]
+  (let [{:keys [path pattern]
+         :or {pattern :daily}} (:rolling ap-config)
+        prev-cal (prev-period-end-cal instant pattern)
+        log (io/file path)]
+    (when log
+      (try
+        (if (.exists log)
+          (if (<= (.lastModified log) (.getTimeInMillis prev-cal))
+            (shift-log-period log path prev-cal))
+          (.createNewFile log))
+        (spit path (with-out-str (timbre/str-println output)) :append true)
+        (catch java.io.IOException _)))))
+
+(defn make-rolling-appender
+  "Returns a Rolling file appender.
+  A rolling config map can be provided here as an argument, or as a :rolling key
+  in :shared-appender-config.
+
+  (make-rolling-appender {:enabled? true}
+    {:path \"log/app.log\"
+     :pattern :daily})
+  path: logfile path
+  pattern: frequency of rotation, avialable values: :daily (default), :weekly, :monthly"
+  [& [appender-opts {:keys [path pattern]
+                     :or {pattern :daily}}]]
+  (let [default-appender-opts {:enabled? true :min-level nil}]
+    (merge default-appender-opts appender-opts
+      {:fn appender-fn})))