Merge pull request #18 from emlyn/socket

TCP Socket Appender (emlyn)

README.md

@@ -154,6 +154,25 @@ Filter logging output by namespaces:
                      :chan "#logs"})
 ```
 
+#### Socket ([server-socket](https://github.com/technomancy/server-socket)) appender
+
+Listens on the specified interface (use :all for all interfaces, defaults to localhost if unspecified) and port. Connect with either of:
+
+```
+telnet localhost 9000
+netcat localhost 9000
+```
+
+```clojure
+;; [server-socket "1.0.0"] ; Add to project.clj dependencies
+;; (:require [taoensso.timbre.appenders (socket :as socket-appender)]) ; Add to ns
+
+(timbre/set-config! [:appenders :socket] socket-appender/socket-appender)
+(timbre/set-config! [:shared-appender-config :socket]
+                    {:listen-addr :all
+                     :port 9000})
+```
+
 ### Custom appenders
 
 Writing a custom appender is dead-easy:
@@ -179,7 +198,7 @@ See the `timbre/config` docstring for more information on appenders.
 
 The usual recommendation for Clojure profiling is: use a good **JVM profiler** like [YourKit](http://www.yourkit.com/), [JProfiler](http://www.ej-technologies.com/products/jprofiler/overview.html), or [VisualVM](http://docs.oracle.com/javase/6/docs/technotes/guides/visualvm/index.html).
 
-And these certainly do the job. But as with many Java tools, they can be a little hairy and often heavy-handed - especially when applied to Clojure. Timbre includes an alternative. 
+And these certainly do the job. But as with many Java tools, they can be a little hairy and often heavy-handed - especially when applied to Clojure. Timbre includes an alternative.
 
 Let's add it to our app's `ns` declaration:
 

src/taoensso/timbre/appenders/socket.clj

@@ -0,0 +1,49 @@
+(ns taoensso.timbre.appenders.socket
+  "TCP Socket appender. Depends on https://github.com/technomancy/server-socket."
+  {:author "Emlyn Corrin"}
+  (:require [server.socket :refer [create-server]]
+            [taoensso.timbre :refer [stacktrace]])
+  (:import [java.net Socket InetAddress]
+           [java.io BufferedReader InputStreamReader PrintWriter]))
+
+(def conn (atom nil))
+
+(defn listener-fun [in out]
+  (loop [lines (-> in
+                   (InputStreamReader.)
+                   (BufferedReader.)
+                   (line-seq))]
+    (when-not (re-find #"(?i)^quit" (first lines))
+      (recur (rest lines)))))
+
+(defn on-thread-daemon [f]
+  (doto (Thread. ^Runnable f)
+    (.setDaemon true)
+    (.start)))
+
+(defn connect [{:keys [port listen-addr]}]
+  (let [addr (when (not= :all listen-addr)
+               (InetAddress/getByName listen-addr))]
+    (with-redefs [server.socket/on-thread on-thread-daemon]
+      (create-server port listener-fun 0 ^InetAddress addr))))
+
+(defn ensure-conn [socket-config]
+  (swap! conn #(or % (connect socket-config))))
+
+(defn appender-fn [{:keys [ap-config prefix message throwable] :as params}]
+  (when-let [socket-config (:socket ap-config)]
+    (let [c (ensure-conn socket-config)]
+      (doseq [sock @(:connections c)]
+        (let [out (PrintWriter. (.getOutputStream ^Socket sock))]
+          (binding [*out* out]
+            (println prefix message
+                     (stacktrace throwable))))))))
+
+(def socket-appender
+  {:doc (str "Logs to a listening socket.\n"
+             "Needs :socket config map in :shared-appender-config, e.g.:
+             {:listen-addr :all
+              :port 9000}")
+   :min-level :trace :enabled? true :async? false
+   :max-message-per-msecs nil ; no rate limit by default
+   :fn appender-fn})