Pre-compressed .gz files support

project.clj

@@ -3,4 +3,6 @@
                user-agents."
   :url "https://github.com/bertrandk/ring-gzip"
   :license {:name "MIT-style license (see LICENSE for details)."}
+  :global-vars {*warn-on-reflection* true}
+  :profiles {:test {:resource-paths ["test"]}}
   :dependencies [[org.clojure/clojure "1.5.1"]])

src/ring/middleware/gzip.clj

@@ -6,6 +6,7 @@
                     File
                     PipedInputStream
                     PipedOutputStream)
+           (java.net URL)
            (java.util.zip GZIPOutputStream)))
 
 (defn- accepts-gzip?
@@ -15,21 +16,25 @@
     ;; proxies, av software, buggy browsers, etc...)
     (re-seq
       #"(gzip\s*,?\s*(gzip|deflate)?|X{4,13}|~{4,13}|\-{4,13})"
-      accepts)))
+      (str accepts))))
 
 ;; Set Vary to make sure proxies don't deliver the wrong content.
-(defn- set-response-headers
+(defn- set-encoding-headers
   [headers]
   (if-let [vary (get headers "vary")]
     (-> headers
       (assoc "Vary" (str vary ", Accept-Encoding"))
       (assoc "Content-Encoding" "gzip")
-      (dissoc "Content-Length")
       (dissoc "vary"))
     (-> headers
       (assoc "Vary" "Accept-Encoding")
-      (assoc "Content-Encoding" "gzip")
-      (dissoc "Content-Length"))))
+      (assoc "Content-Encoding" "gzip"))))
+
+(defn- set-response-headers
+  [headers]
+  (-> headers
+    (set-encoding-headers)
+    (dissoc "Content-Length")))
 
 (def ^:private supported-status? #{200, 201, 202, 203, 204, 205 403, 404})
 
@@ -56,7 +61,7 @@
     (cond
       (string? body) (> (count body) min-length)
       (seq? body) (> (count body) min-length)
-      (instance? File body) (> (.length body) min-length)
+      (instance? File body) (> (.length ^File body) min-length)
       :else true)))
 
 (defn- supported-response?
@@ -77,7 +82,7 @@
           (doseq [string body] (io/copy (str string) out))
           (io/copy body out)))
       (when (instance? Closeable body)
-        (.close body)))
+        (.close ^Closeable body)))
     p-in))
 
 (defn- gzip-response
@@ -86,6 +91,12 @@
     (update-in [:headers] set-response-headers)
     (update-in [:body] compress-body)))
 
+(defn- gzip-static-response
+  [resp gzfile]
+  (-> resp
+    (update-in [:headers] set-encoding-headers)
+    (assoc :body gzfile)))
+
 (defn wrap-gzip
   "Middleware that compresses responses with gzip for supported user-agents."
   [handler]
@@ -96,3 +107,27 @@
           (gzip-response resp)
           resp))
       (handler req))))
+
+(defn wrap-gzip-static
+  "Middleware that returns pre-compressed files (if available) for supported user-agents.
+
+  Inspired by the NGiNX module: http://nginx.org/en/docs/http/ngx_http_gzip_static_module.html
+
+  Given a resource or File body
+   and the same file with .gz appended exists
+   it will return the .gz one instead."
+  [handler]
+  (fn [req]
+    (let [{body :body :as resp} (handler req)
+          ^File file (if (instance? File body)
+                       body
+                       (if (instance? URL body)
+                         (try (io/file body) (catch IllegalArgumentException e))))]
+      (if (and file (accepts-gzip? req))
+        (let [gzfile (File. (str file ".gz"))]
+          (if (.exists gzfile)
+            (gzip-static-response resp gzfile)
+          ;else
+            resp))
+      ;else
+        resp))))

test/ring/middleware/gzip_test.clj

@@ -140,3 +140,24 @@
                                 resp ((wrap-gzip handler) req)]]
                     (is (= (get-in resp [:headers "Content-Encoding"])
                            "gzip")))))
+
+(deftest test-wrap-gzip-static
+         (testing "Precompressed static resource file response"
+                  (let [handler (constantly {:status 200
+                                             :headers {}
+                                             :body (io/resource "text.txt")})
+                        req (req :headers {"accept-encoding" "gzip"})
+                        resp ((wrap-gzip-static handler) req)]
+                    (is (= (get-in resp [:headers "Content-Encoding"])
+                           "gzip"))
+                    (is (= (.toURI (:body resp)) (.toURI (io/resource "text.txt.gz"))))))
+
+         (testing "Precompressed static file response"
+                  (let [handler (constantly {:status 200
+                                             :headers {}
+                                             :body (io/file "test/text.txt")})
+                        req (req :headers {"accept-encoding" "gzip"})
+                        resp ((wrap-gzip-static handler) req)]
+                    (is (= (get-in resp [:headers "Content-Encoding"])
+                           "gzip"))
+                    (is (= (:body resp) (io/file "test/text.txt.gz"))))))

test/text.txt

@@ -0,0 +1 @@
+Testing 123