handle exceptions

src/metabase/routes.clj

@@ -53,6 +53,9 @@
   (Thread/sleep 30000)
   {:success true})
 
+(defn- some-naughty-handler-that-barfs [_]
+  (throw (Exception. "BARF!")))
+
 (def ^:private ^:const streaming-response-keep-alive-interval-ms
   "Interval between sending whitespace bytes to keep Heroku from terminating
    requests like queries that take a long time to complete."
@@ -60,9 +63,14 @@
 
 (defn- streaming-response [handler]
   (fn [request]
-    ;; TODO - handle exceptions  & have some sort of maximum timeout for these requests
+    ;; TODO - need maximum timeout for requests
+    ;; TODO - error response should have status code != 200 (how ?)
+    ;; TODO - handle exceptions in JSON encoding as well
     (-> (fn [^java.io.PipedOutputStream ostream]
-          (let [response       (future (handler request))
+          (let [response       (future (try (handler request)
+                                            (catch Throwable e
+                                              {:error      (.getMessage e)
+                                               :stacktrace (u/filtered-stacktrace e)})))
                 write-response (future (json/generate-stream @response (io/writer ostream))
                                        (println "Done! closing ostream...")
                                        (.close ostream))]
@@ -103,5 +111,7 @@
   (context "/embed" [] embed-routes)
   (context "/stream-test" []
     (streaming-response some-very-long-handler))
+  (context "/stream-test-2" []
+      (streaming-response some-naughty-handler-that-barfs))
   ;; Anything else (e.g. /user/edit_current) should serve up index.html; React app will handle the rest
   (GET "*" [] index))