From db71943a5bf3bf958d27776a0f170832002a967e Mon Sep 17 00:00:00 2001
From: Peter Taoussanis <ptaoussanis@gmail.com>
Date: Sat, 25 Jul 2020 10:15:27 +0200
Subject: [PATCH] [#122] Option to disable freezing and/or thawing of metadata

---
 src/taoensso/nippy.clj             | 16 +++++++++-----
 test/taoensso/nippy/tests/main.clj | 35 ++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 6 deletions(-)

diff --git a/src/taoensso/nippy.clj b/src/taoensso/nippy.clj
index 14bd3d1..dfaf3ac 100644
--- a/src/taoensso/nippy.clj
+++ b/src/taoensso/nippy.clj
@@ -35,7 +35,6 @@
 
 ;;;; TODO
 ;; - Performance would benefit from ^:static support / direct linking / etc.
-;; - Ability to compile out metadata support?
 ;; - Auto cache keywords? When map keys? Configurable? Per-map
 ;;   (`cache-keys`)? Just rely on compression?
 
@@ -281,6 +280,8 @@
   nil => default"
   nil)
 
+(enc/defonce ^:dynamic *incl-metadata?* "Include metadata when freezing/thawing?" true)
+
 (def default-serializable-whitelist
   "PRs welcome to add additional known-safe classes to default."
   #{"[I" "[F" "[Z" "[B" "[C" "[D" "[S" "[J"
@@ -475,7 +476,7 @@
 (extend-protocol IFreezable2 ; Must be a separate protocol
   clojure.lang.IMeta
   (-freeze-with-meta! [x ^DataOutput data-output]
-    (let [m (.meta x)]
+    (let [m (when *incl-metadata?* (.meta x))]
       (when m
         (write-id data-output id-meta)
         (-freeze-without-meta! m data-output)))
@@ -1168,7 +1169,8 @@
             (opt->bindings :freeze-fallback        #'*freeze-fallback*)
             (opt->bindings :auto-freeze-compressor #'*auto-freeze-compressor*)
             (opt->bindings :serializable-whitelist #'*serializable-whitelist*)
-            (opt->bindings :custom-readers         #'*custom-readers*))]
+            (opt->bindings :custom-readers         #'*custom-readers*)
+            (opt->bindings :incl-metadata?         #'*incl-metadata?*))]
 
       (if-not bindings
         (f) ; Common case
@@ -1204,7 +1206,7 @@
   types, extend the Clojure reader or see `extend-freeze`."
   ([x] (freeze x nil))
   ([x {:as   opts
-       :keys [compressor encryptor password serializable-whitelist]
+       :keys [compressor encryptor password serializable-whitelist incl-metadata?]
        :or   {compressor :auto
               encryptor  aes128-gcm-encryptor}}]
 
@@ -1472,7 +1474,9 @@
         id-false       false
         id-char        (.readChar in)
         id-meta        (let [m (thaw-from-in! in)]
-                         (with-meta (thaw-from-in! in) m))
+                         (if *incl-metadata?*
+                           (with-meta (thaw-from-in! in) m)
+                           (do        (thaw-from-in! in))))
 
         id-cached-0    (thaw-cached 0 in)
         id-cached-1    (thaw-cached 1 in)
@@ -1656,7 +1660,7 @@
   ([^bytes ba
     {:as   opts
      :keys [v1-compatibility? compressor encryptor password
-            serializable-whitelist]
+            serializable-whitelist incl-metadata?]
      :or   {compressor :auto
             encryptor  :auto}}]
 
diff --git a/test/taoensso/nippy/tests/main.clj b/test/taoensso/nippy/tests/main.clj
index b917a9d..8d396aa 100644
--- a/test/taoensso/nippy/tests/main.clj
+++ b/test/taoensso/nippy/tests/main.clj
@@ -296,6 +296,41 @@
   (is (= nippy/*serializable-whitelist* #{"base.1" "base.2" "add.1" "add.2"})
     "JVM properties override initial serializable-whitelist value"))
 
+
+;;;; Metadata
+
+(deftest _metadata
+
+  (is
+    (:has-meta?
+     (meta
+       (nippy/thaw
+         (nippy/freeze (with-meta [] {:has-meta? true}) {:incl-metadata? true})
+         {:incl-metadata? true}
+         )))
+
+    "Metadata successfully included")
+
+  (is
+    (nil?
+      (meta
+        (nippy/thaw
+          (nippy/freeze (with-meta [] {:has-meta? true}) {:incl-metadata? true})
+          {:incl-metadata? false}
+          )))
+
+    "Metadata successfully excluded by thaw")
+
+  (is
+    (nil?
+      (meta
+        (nippy/thaw
+          (nippy/freeze (with-meta [] {:has-meta? true}) {:incl-metadata? false})
+          {:incl-metadata? true}
+          )))
+
+    "Metadata successfully excluded by freeze"))
+
 ;;;; Benchmarks
 
 (deftest _benchmarks