EXPERIMENTAL: Swap Snappy implementation org.xerial.snappy/snappy-java -> org.iq80.snappy/snappy

This (native Java) implementation appears to be about as fast as
the old (JNI) implementation, but has better support across more platforms.

Going to evaluate stability on this branch for possible later merging into master.

project.clj

@@ -2,8 +2,8 @@
   :description "Clojure serialization library"
   :url "https://github.com/ptaoussanis/nippy"
   :license {:name "Eclipse Public License"}
-  :dependencies [[org.clojure/clojure           "1.3.0"]
+  :dependencies [[org.clojure/clojure    "1.3.0"]
-                 [org.xerial.snappy/snappy-java "1.0.5-M3"]]
+                 [org.iq80.snappy/snappy "0.2"]]
   :profiles {:1.3  {:dependencies [[org.clojure/clojure "1.3.0"]]}
              :1.4  {:dependencies [[org.clojure/clojure "1.4.0"]]}
              :1.5  {:dependencies [[org.clojure/clojure "1.5.0-alpha3"]]}

src/taoensso/nippy.clj

@@ -5,7 +5,6 @@
   (:require [taoensso.nippy.utils :as utils])
   (:import  [java.io DataInputStream DataOutputStream ByteArrayOutputStream
              ByteArrayInputStream]
-            [org.xerial.snappy Snappy]
             [clojure.lang IPersistentList IPersistentVector IPersistentMap
              IPersistentSet PersistentQueue IPersistentCollection Keyword
              BigInt Ratio]))
@@ -165,7 +164,7 @@
         stream (DataOutputStream. ba)]
     (freeze-to-stream! stream x print-dup?)
     (let [ba (.toByteArray ba)]
-      (if compress? (Snappy/compress ba) ba))))
+      (if compress? (utils/compress-bytes ba) ba))))
 
 ;;;; Thawing
 
@@ -243,7 +242,7 @@
   [ba & {:keys [read-eval? compressed?]
          :or   {read-eval?  false ; For `read-string` injection safety - NB!!!
                 compressed? true}}]
-  (-> (if compressed? (Snappy/uncompress ba) ba)
+  (-> (if compressed? (utils/uncompress-bytes ba) ba)
       (ByteArrayInputStream.)
       (DataInputStream.)
       (thaw-from-stream! read-eval?)))

src/taoensso/nippy/benchmarks.clj

@@ -45,4 +45,10 @@
   (let [frozen (reader-freeze data)]   (count (.getBytes frozen "UTF8")))
   (let [frozen (freeze-to-bytes data)] (count frozen))
   ;; 22788, 12224
+
+  ;;; Snappy implementations
+  (println (bench (roundtrip data)))
+  ;;                No Snappy: 6163 6064 6042 6176
+  ;;               Snappy JNI: 6489 6446 6542 6412
+  ;; Snappy native array copy: 6569 6419 6414 6590
   )

src/taoensso/nippy/utils.clj

@@ -1,6 +1,7 @@
 (ns taoensso.nippy.utils
   {:author "Peter Taoussanis"}
-  (:require [clojure.string :as str]))
+  (:require [clojure.string :as str])
+  (:import  org.iq80.snappy.Snappy))
 
 (defmacro case-eval
   "Like `case` but evaluates test constants for their compile-time value."
@@ -55,4 +56,15 @@
 (defn version-sufficient?
   [version-str min-version-str]
   (try (>= (version-compare version-str min-version-str) 0)
-       (catch Exception _ false)))
+       (catch Exception _ false)))
+
+;; TODO Unnecessarily complicated. Waiting on http://goo.gl/7mbR3 merge.
+(defn compress-bytes [ba]
+  (let [ba-size     (alength ^bytes ba)
+        ba-out      (byte-array (Snappy/maxCompressedLength ba-size))
+        ba-out-size (Snappy/compress ba (int 0) (int ba-size) ba-out (int 0))]
+    (java.util.Arrays/copyOf ba-out ba-out-size)))
+
+(defn uncompress-bytes [ba] (Snappy/uncompress ba 0 (alength ^bytes ba)))
+
+(comment (String. (uncompress-bytes (compress-bytes (.getBytes "Test")))))