[mod] Remove nippy/snappy-compressor

Details:

  - Nippy will continue to support thawing OLD data that was originally compressed with Snappy.
  - But Nippy will no longer support freezing NEW data with Snappy.

Motivation:

  - The current Snappy implementation can cause JVM crashes in some cases [1].

  - The only alternative JVM implementation that seems to be safe [2] uses JNI and
    so would introduce possible incompatibility issues even for folks not using Snappy.

  - Nippy already moved to the superior LZ4 as its default compression scheme in v2.7.0,
    more than 9 years ago.

[1] Ref. <https://github.com/airlift/aircompressor/issues/183>
[2] Ref. <https://github.com/xerial/snappy-java>

project.clj

@@ -11,9 +11,7 @@
   [[org.clojure/tools.reader "1.3.7"]
    [com.taoensso/encore      "3.77.0"]
    [org.tukaani/xz           "1.9"]
-   [io.airlift/aircompressor "0.25"]
-   [org.iq80.snappy/snappy   "0.4"]
-   [org.xerial.snappy/snappy-java "1.1.10.5"]]
+   [io.airlift/aircompressor "0.25"]]
 
   :profiles
   {;; :default [:base :system :user :provided :dev]

src/taoensso/nippy.clj

@@ -337,7 +337,7 @@
   compression/lz4-compressor
   compression/lz4hc-compressor
   #_compression/lzo-compressor
-  compression/snappy-compressor
+  #_compression/snappy-compressor ; Can be unsafe
   compression/lzma2-compressor
 
   encryption/encrypt
@@ -1704,7 +1704,7 @@
 (defn- get-auto-compressor [compressor-id]
   (case compressor-id
     nil        nil
-    :snappy    snappy-compressor
+    :snappy    compression/snappy-compressor
     :lzma2     lzma2-compressor
     :lz4       lz4-compressor
     :no-header (throw (ex-info ":auto not supported on headerless data." {}))
@@ -1806,7 +1806,7 @@
 
                    (catch Exception e (ex-fn e)))))
 
-             ;; Hackish + can actually segfault JVM due to Snappy bug,
+             ;; Hacky + can actually segfault JVM due to Snappy bug,
              ;; Ref. <http://goo.gl/mh7Rpy> - no better alternatives, unfortunately
              thaw-v1-data
              (fn [data-ba ex-fn]

src/taoensso/nippy/compression.clj

@@ -116,8 +116,6 @@
     (compress   [_ ba] (airlift-compress   @airlift-lzo-compressor_   ba true))
     (decompress [_ ba] (airlift-decompress @airlift-lzo-decompressor_ ba nil))))
 
-;; Using `io.airlift/aircompressor`, vulnerable to https://github.com/airlift/aircompressor/issues/183
-#_
 (do
   (enc/def* ^:private airlift-snappy-compressor_   (enc/thread-local (io.airlift.compress.snappy.SnappyCompressor.)))
   (enc/def* ^:private airlift-snappy-decompressor_ (enc/thread-local (io.airlift.compress.snappy.SnappyDecompressor.)))
@@ -129,21 +127,6 @@
                          (when-not prepend-size?
                            (io.airlift.compress.snappy.SnappyDecompressor/getUncompressedLength ba 0))))))
 
-;; Using `org.iq80.snappy/snappy`, vulnerable to https://github.com/airlift/aircompressor/issues/183
-#_
-(deftype SnappyCompressor [_]
-  ICompressor
-  (header-id  [_] :snappy)
-  (compress   [_ ba] (org.iq80.snappy.Snappy/compress   ba))
-  (decompress [_ ba] (org.iq80.snappy.Snappy/uncompress ba 0 (alength ^bytes ba))))
-
-;; Using `org.xerial.snappy/snappy-java`, some compatibility issues due to JNI
-(deftype SnappyCompressor [_]
-  ICompressor
-  (header-id  [_] :snappy)
-  (compress   [_ ba] (org.xerial.snappy.Snappy/compress   ba))
-  (decompress [_ ba] (org.xerial.snappy.Snappy/uncompress ba)))
-
 ;;;; LZMA2
 
 (deftype LZMA2Compressor [compression-level]
@@ -208,16 +191,6 @@
   See `taoensso.nippy-benchmarks` for detailed comparative benchmarks."
   (LZOCompressor.))
 
-(def snappy-compressor
-  "Default `Snappy` compressor:
-    -   Compression ratio: `C`  (0.58      on reference benchmark).
-    -   Compression speed: `A+` (206 msecs on reference benchmark).
-    - Decompression speed: `B`  (134 msecs on reference benchmark).
-
-  Good general-purpose compressor, favours speed.
-  See `taoensso.nippy-benchmarks` for detailed comparative benchmarks."
-  (SnappyCompressor. false))
-
 (def lzma2-compressor
   "Default `LZMA2` compressor:
     -   Compression ratio: `A+` (0.4       on reference benchmark).
@@ -232,3 +205,9 @@
   "Different LZ4 modes no longer supported, prefer `lz4-compressor`."
   {:deprecated "vX.Y.Z (YYYY-MM-DD)"}
   (LZ4Compressor.))
+
+(enc/def* ^:no-doc snappy-compressor
+  "Snappy compressor no longer recommended, prefer `lz4-compressor`.
+  Decompression can be unsafe against untrusted data!"
+  {:deprecated "vX.Y.Z (YYYY-MM-DD)"}
+  (SnappyCompressor. false))

test/taoensso/nippy_tests.clj

@@ -426,13 +426,13 @@
   (doseq [c [compr/zstd-compressor
              compr/lz4-compressor
              compr/lzo-compressor
-             compr/snappy-compressor
+             #_compr/snappy-compressor ; Ref. <https://github.com/airlift/aircompressor/issues/183>
              compr/lzma2-compressor]]
 
     (dotimes [_ 2e4]
       (is
         (nil? (enc/catching (compr/decompress c (crypto/rand-bytes 1024))))
-        "Decompression never core dumps, even against invalid data"))))
+        "Decompression never crashes JVM, even against invalid data"))))
 
 ;;;; Benchmarks