Experimental: add inspect-ba util for inspecting possibly-frozen data

CHANGELOG.md

@@ -1,3 +1,17 @@
+## WIP / 2013-12-03
+
+WIP
+
+### Features
+ * Added experimental `inspect-ba` fn for examining data possibly frozen by Nippy.
+
+### Changes
+ *
+
+### Fixes
+ *
+
+
 ## v2.4.1 → v2.5.0
   * Refactored standard Freezable protocol implementations to de-emphasise interfaces as a matter of hygiene, Ref. http://goo.gl/IFXzvh.
   * BETA STATUS: Added an additional (pre-Reader) Serializable fallback. This should greatly extend the number of out-the-box-serializable types.

src/taoensso/nippy.clj

@@ -266,6 +266,8 @@
 (defn- thaw-from-stream
   [^DataInputStream s]
   (let [type-id (.readByte s)]
+    #_(when debug-mode?
+        (println (format "DEBUG - thawing type-id: %s" type-id)))
     (utils/case-eval type-id
 
      id-reader  (edn/read-string {:readers *data-readers*} (read-utf8 s))
@@ -531,6 +533,34 @@
      :exception    (try (/ 1 0) (catch Exception e e))
      :ex-info      (ex-info "ExInfo" {:data "data"})}))
 
+;;;; Data recovery/analysis
+
+(defn inspect-ba "Alpha - subject to change."
+  [ba & [thaw-opts]]
+  (if-not (utils/bytes? ba) :not-ba
+    (let [[first2bytes nextbytes] (utils/ba-split ba 2)
+          known-wrapper
+          (cond
+           (utils/ba= first2bytes (.getBytes "\u0000<" "UTF8")) :carmine/bin
+           (utils/ba= first2bytes (.getBytes "\u0000>" "UTF8")) :carmine/clj)
+
+          unwrapped-ba (if known-wrapper nextbytes ba)
+          [data-ba nippy-header] (or (try-parse-header unwrapped-ba)
+                                     [unwrapped-ba :no-header])]
+
+      {:known-wrapper  known-wrapper
+       :nippy2-header  nippy-header ; Nippy v1.x didn't have a header
+       :thawable?      (try (thaw unwrapped-ba thaw-opts) true
+                            (catch Exception _ false))
+       :unwrapped-ba   unwrapped-ba
+       :data-ba        data-ba
+       :unwrapped-size (alength ^bytes unwrapped-ba)
+       :ba-size        (alength ^bytes ba)
+       :data-size      (alength ^bytes data-ba)})))
+
+(comment (inspect-ba (freeze "hello"))
+         (seq (:data-ba (inspect-ba (freeze "hello")))))
+
 ;;;; Deprecated API
 
 (defn- assert-legacy-args [compressor password]

src/taoensso/nippy/utils.clj

@@ -74,6 +74,8 @@
 (comment (memoized nil +)
          (memoized nil + 5 12))
 
+(def ^:const bytes-class (Class/forName "[B"))
+(defn bytes? [x] (instance? bytes-class x))
 (defn ba= [^bytes x ^bytes y] (java.util.Arrays/equals x y))
 
 (defn ba-concat ^bytes [^bytes ba1 ^bytes ba2]