Merge pull request #521 from prepor/error-handler

Customizable error handler

Author: KingMob

src/aleph/http/server.clj

@@ -117,13 +117,13 @@
       [server-value keep-alive-value close-value]
       (map #(HttpHeaders/newEntity %) ["Aleph/0.5.0" "Keep-Alive" "Close"])]
   (defn send-response
-    [^ChannelHandlerContext ctx keep-alive? ssl? rsp]
+    [^ChannelHandlerContext ctx keep-alive? ssl? error-handler rsp]
     (let [[^HttpResponse rsp body]
           (try
             [(http/ring-response->netty-response rsp)
              (get rsp :body)]
             (catch Throwable e
-              (let [rsp (error-response e)]
+              (let [rsp (error-handler e)]
                 [(http/ring-response->netty-response rsp)
                  (get rsp :body)])))]
 
@@ -142,20 +142,20 @@
 
 ;;;
 
-(defn invalid-value-response [req x]
-  (error-response
-    (IllegalArgumentException.
-      (str "cannot treat "
+(defn invalid-value-exception [req x]
+  (IllegalArgumentException.
+   (str "cannot treat "
         (pr-str x)
         " as HTTP response for request to '"
         (:uri req)
-        "'"))))
+        "'")))
 
 (defn handle-request
   [^ChannelHandlerContext ctx
    ssl?
    handler
    rejected-handler
+   error-handler
    executor
    ^HttpRequest req
    previous-response
@@ -168,13 +168,13 @@
               ;; handle request on a separate thread
               (try
                 (d/future-with executor
-                  (handler req'))
+                               (handler req'))
                 (catch RejectedExecutionException e
                   (if rejected-handler
                     (try
                       (rejected-handler req')
                       (catch Throwable e
-                        (error-response e)))
+                        (error-handler e)))
                     {:status 503
                      :headers {"content-type" "text/plain"}
                      :body "503 Service Unavailable"})))
@@ -183,31 +183,31 @@
               (try
                 (handler req')
                 (catch Throwable e
-                  (error-response e))))]
+                  (error-handler e))))]
 
     (-> previous-response
         (d/chain'
-          netty/wrap-future
-          (fn [_]
-            (netty/release req)
-            (-> rsp
-                (d/catch' error-response)
-                (d/chain'
-                  (fn [rsp]
-                    (when (not (-> req' ^AtomicBoolean (.websocket?) .get))
-                      (send-response ctx keep-alive? ssl?
-                                     (cond
-
-                                       (map? rsp)
-                                       (if head?
-                                         (assoc rsp :body :aleph/omitted)
-                                         rsp)
-
-                                       (nil? rsp)
-                                       {:status 204}
-
-                                       :else
-                                       (invalid-value-response req rsp))))))))))))
+         netty/wrap-future
+         (fn [_]
+           (netty/release req)
+           (-> rsp
+               (d/catch' error-handler)
+               (d/chain'
+                (fn [rsp]
+                  (when (not (-> req' ^AtomicBoolean (.websocket?) .get))
+                    (send-response ctx keep-alive? ssl? error-handler
+                                   (cond
+
+                                     (map? rsp)
+                                     (if head?
+                                       (assoc rsp :body :aleph/omitted)
+                                       rsp)
+
+                                     (nil? rsp)
+                                     {:status 204}
+
+                                     :else
+                                     (error-handler (invalid-value-exception req rsp)))))))))))))
 
 (defn exception-handler [ctx ex]
   (cond
@@ -249,7 +249,7 @@
      (fn [_] (netty/close ctx)))))
 
 (defn ring-handler
-  [ssl? handler rejected-handler executor buffer-capacity]
+  [ssl? handler rejected-handler error-handler executor buffer-capacity]
   (let [buffer-capacity (long buffer-capacity)
         request (atom nil)
         buffer (atom [])
@@ -265,6 +265,7 @@
               ssl?
               handler
               rejected-handler
+              error-handler
               executor
               req
               @previous-response
@@ -387,7 +388,7 @@
           (.fireChannelRead ctx msg))))))
 
 (defn raw-ring-handler
-  [ssl? handler rejected-handler executor buffer-capacity]
+  [ssl? handler rejected-handler error-handler executor buffer-capacity]
   (let [buffer-capacity (long buffer-capacity)
         stream (atom nil)
         previous-response (atom nil)
@@ -400,6 +401,7 @@
               ssl?
               handler
               rejected-handler
+              error-handler
               executor
               req
               @previous-response
@@ -513,6 +515,7 @@
    {:keys
     [executor
      rejected-handler
+     error-handler
      request-buffer-size
      max-initial-line-length
      max-header-size
@@ -530,11 +533,12 @@
      max-header-size 8192
      max-chunk-size 16384
      compression? false
-     idle-timeout 0}}]
+     idle-timeout 0
+     error-handler error-response}}]
   (fn [^ChannelPipeline pipeline]
     (let [handler (if raw-stream?
-                    (raw-ring-handler ssl? handler rejected-handler executor request-buffer-size)
-                    (ring-handler ssl? handler rejected-handler executor request-buffer-size))
+                    (raw-ring-handler ssl? handler rejected-handler error-handler executor request-buffer-size)
+                    (ring-handler ssl? handler rejected-handler error-handler executor request-buffer-size))
           ^ChannelHandler
           continue-handler (if (nil? continue-handler)
                              (HttpServerExpectContinueHandler.)

test/aleph/http_test.clj

@@ -103,7 +103,11 @@
   {:status 200
    :body "hello"})
 
-(defn big-handler [_request]
+(defn invalid-handler [_]
+  {:status -100
+   :body "hello"})
+
+(defn big-handler [_]
   {:status 200
    :body (->> (s/periodically 0.1 #(byte-array 1024))
               (s/transform (take (long 1e3))))})
@@ -138,6 +142,7 @@
    "/string" string-handler
    "/echo" echo-handler
    "/line_echo" line-echo-handler
+   "/invalid" invalid-handler
    "/stop" (fn [_]
              (try
                (deliver latch true) ;;this can be triggered more than once, sometimes
@@ -460,6 +465,23 @@
                   :body
                   bs/to-string)))))
 
+(deftest test-invalid-response
+  (with-handler invalid-handler
+    (let [{:keys [body status]} @(http-get (apply str "http://localhost:" port  "/invalid"))]
+      (is (= 500 status))
+      (is (re-find #"java\.lang\.IllegalArgumentException: code : -100 \(expected: >= 0\)"
+                   (bs/to-string body)))))
+  (testing "custom error handler"
+    (with-server (http/start-server invalid-handler
+                                    {:port port
+                                     :error-handler (fn [_]
+                                                      {:status 500
+                                                       :body "Internal error"})})
+      (let [{:keys [body status]} @(http-get (apply str "http://localhost:" port  "/invalid"))]
+        (is (= 500 status))
+        (is (= "Internal error"
+               (bs/to-string body)))))))
+
 ;;;
 
 (defn get-netty-client-event-threads []