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[mod] [DEPRECATED] Remove ability to freeze new data using experimental cache feature

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This commit is BREAKING for those still actively using `nippy/cache`.

Data previously frozen using `nippy/cache` can still be thawed, though
support for thawing may also be removed in a future Nippy version.

Motivation for removal:

  This cache feature (marked as experimental) was always a bit dubious.
  The use cases were very limited, and the complexity quite significant.

  I don't believe that the feature has ever had much (any?) public
  adoption, so I'm removing it here.

  PLEASE LET ME KNOW if this removal negatively impacts you.
This commit is contained in:
Peter Taoussanis 2022-10-14 16:04:08 +02:00
parent 08a50c873f
commit a22c26779f
2 changed files with 26 additions and 140 deletions
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128
src/taoensso/nippy.clj
View file

@ -201,20 +201,21 @@
;; Necessarily without size information
81 [:type nil]
82 [:prefixed-custom-md nil]
59 [:cached-0 nil]
63 [:cached-1 nil]
64 [:cached-2 nil]
65 [:cached-3 nil]
66 [:cached-4 nil]
72 [:cached-5 nil]
73 [:cached-6 nil]
74 [:cached-7 nil]
67 [:cached-sm nil]
68 [:cached-md nil]
;;; DEPRECATED (only support thawing)
;; Desc-sorted by deprecation date
59 [:cached-0_ nil] ; [2022-10-14 v3.3.0]
63 [:cached-1_ nil] ; [2022-10-14 v3.3.0]
64 [:cached-2_ nil] ; [2022-10-14 v3.3.0]
65 [:cached-3_ nil] ; [2022-10-14 v3.3.0]
66 [:cached-4_ nil] ; [2022-10-14 v3.3.0]
72 [:cached-5_ nil] ; [2022-10-14 v3.3.0]
73 [:cached-6_ nil] ; [2022-10-14 v3.3.0]
74 [:cached-7_ nil] ; [2022-10-14 v3.3.0]
67 [:cached-sm_ nil] ; [2022-10-14 v3.3.0]
68 [:cached-md_ nil] ; [2022-10-14 v3.3.0]
78 [:sym-md_ [[:bytes {:read 4}]]] ; [2020-11-18 v3.1.1] Buggy size field, Ref. #138
77 [:kw-md_ [[:bytes {:read 4}]]] ; [2020-11-18 v3.1.1] Buggy size field, Ref. #138
@ -1079,86 +1080,16 @@
(write-id ~'out ~id)
~@body)))
;;;; Caching ; Experimental
;; Nb: don't use an auto initialValue; can cause thread-local state to
;; accidentally hang around with the use of `freeze-to-out!`, etc.
;; Safer to require explicit activation through `with-cache`.
(def ^ThreadLocal -cache-proxy
"{[<x> <meta>] <idx>} for freezing, {<idx> <x-with-meta>} for thawing."
(proxy [ThreadLocal] []))
;;;; Caching (deprecated)
(def ^ThreadLocal -cache-proxy (proxy [ThreadLocal] []))
(defmacro ^:private with-cache
"Experimental, subject to change.
Executes body with support for freezing/thawing cached values.
This is a low-level util: you won't need to use this yourself unless
you're using `freeze-to-out!` or `thaw-from-in!` (also low-level utils).
See also `cache`."
[& body]
`(try
(.set -cache-proxy (volatile! nil))
(do ~@body)
(finally (.remove -cache-proxy))))
(deftype Cached [val])
(defn cache
"Experimental, subject to change.
Wraps value so that future writes of the same wrapped value with same
metadata will be efficiently encoded as references to this one.
(freeze [(cache \"foo\") (cache \"foo\") (cache \"foo\")])
will incl. a single \"foo\", plus 2x single-byte references to \"foo\"."
[x]
(if (instance? Cached x) x (Cached. x)))
(comment (cache "foo"))
(freezer Cached
(let [x-val (.-val x)]
(if-let [cache_ (.get -cache-proxy)]
(let [cache @cache_
k #_x-val [x-val (meta x-val)]
?idx (get cache k)
^int idx (or ?idx
(let [idx (count cache)]
(vswap! cache_ assoc k idx)
idx))
first-occurance? (nil? ?idx)]
(enc/cond
(sm-count? idx)
(case (int idx)
0 (do (write-id out id-cached-0) (when first-occurance? (-freeze-with-meta! x-val out)))
1 (do (write-id out id-cached-1) (when first-occurance? (-freeze-with-meta! x-val out)))
2 (do (write-id out id-cached-2) (when first-occurance? (-freeze-with-meta! x-val out)))
3 (do (write-id out id-cached-3) (when first-occurance? (-freeze-with-meta! x-val out)))
4 (do (write-id out id-cached-4) (when first-occurance? (-freeze-with-meta! x-val out)))
5 (do (write-id out id-cached-5) (when first-occurance? (-freeze-with-meta! x-val out)))
6 (do (write-id out id-cached-6) (when first-occurance? (-freeze-with-meta! x-val out)))
7 (do (write-id out id-cached-7) (when first-occurance? (-freeze-with-meta! x-val out)))
(do
(write-id out id-cached-sm)
(write-sm-count out idx)
(when first-occurance? (-freeze-with-meta! x-val out))))
(md-count? idx)
(do
(write-id out id-cached-md)
(write-md-count out idx)
(when first-occurance? (-freeze-with-meta! x-val out)))
:else
;; (throw (ex-info "Max cache size exceeded" {:idx idx}))
(-freeze-with-meta! x-val out) ; Just freeze uncached
))
(-freeze-with-meta! x-val out))))
(declare thaw-from-in!)
(def ^:private thaw-cached
(let [not-found (Object.)]
@ -1173,13 +1104,6 @@
(throw (ex-info "No cache_ established, can't thaw. See `with-cache`."
{}))))))
(comment
(thaw (freeze [(cache "foo") (cache "foo") (cache "foo")]))
(let [v1 (with-meta [] {:id :v1})
v2 (with-meta [] {:id :v2})]
(mapv meta
(thaw (freeze [(cache v1) (cache v2) (cache v1) (cache v2)])))))
;;;;
(id-freezer nil id-nil)
@ -1377,7 +1301,7 @@
[x]
(let [baos (ByteArrayOutputStream. 64)
dos (DataOutputStream. baos)]
(with-cache (-freeze-with-meta! x dos))
(-freeze-with-meta! x dos)
(.toByteArray baos)))
(defn freeze
@ -1405,11 +1329,11 @@
(when-not no-header? ; Avoid `wrap-header`'s array copy:
(let [head-ba (get-head-ba {:compressor-id nil :encryptor-id nil})]
(.write dos head-ba 0 4)))
(with-cache (-freeze-with-meta! x dos))
(-freeze-with-meta! x dos)
(.toByteArray baos))
(do
(with-cache (-freeze-with-meta! x dos))
(-freeze-with-meta! x dos)
(let [ba (.toByteArray baos)
compressor
@ -1679,16 +1603,16 @@
(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)
id-cached-2 (thaw-cached 2 in)
id-cached-3 (thaw-cached 3 in)
id-cached-4 (thaw-cached 4 in)
id-cached-5 (thaw-cached 5 in)
id-cached-6 (thaw-cached 6 in)
id-cached-7 (thaw-cached 7 in)
id-cached-sm (thaw-cached (read-sm-count in) in)
id-cached-md (thaw-cached (read-md-count in) in)
id-cached-0_ (thaw-cached 0 in)
id-cached-1_ (thaw-cached 1 in)
id-cached-2_ (thaw-cached 2 in)
id-cached-3_ (thaw-cached 3 in)
id-cached-4_ (thaw-cached 4 in)
id-cached-5_ (thaw-cached 5 in)
id-cached-6_ (thaw-cached 6 in)
id-cached-7_ (thaw-cached 7 in)
id-cached-sm_ (thaw-cached (read-sm-count in) in)
id-cached-md_ (thaw-cached (read-md-count in) in)
id-bytes-0 (byte-array 0)
id-bytes-sm (read-bytes in (read-sm-count in))

38
test/taoensso/nippy/tests/main.clj
View file

@ -133,44 +133,6 @@
(let [mr (MyRec. "basic" "fancy")]
(= mr (thaw (freeze mr))))))))
;;;; Caching
(deftest _caching
(let [stress [nippy/stress-data-comparable
nippy/stress-data-comparable
nippy/stress-data-comparable
nippy/stress-data-comparable]
cached (mapv nippy/cache stress)
cached (mapv nippy/cache stress) ; <=1 wrap auto-enforced
]
(is (= stress (thaw (freeze stress {:compressor nil}))))
(is (= stress (thaw (freeze cached {:compressor nil}))))
(let [size-stress (count (freeze stress {:compressor nil}))
size-cached (count (freeze cached {:compressor nil}))]
(is (>= size-stress (* 3 size-cached)))
(is (< size-stress (* 4 size-cached))))))
(deftest _caching-metadata
(let [v1 (with-meta [] {:id :v1})
v2 (with-meta [] {:id :v2})
frozen-without-caching (freeze [v1 v2 v1 v2])
frozen-with-caching
(freeze [(nippy/cache v1)
(nippy/cache v2)
(nippy/cache v1)
(nippy/cache v2)])]
(is (> (count frozen-without-caching)
(count frozen-with-caching)))
(is (= (thaw frozen-without-caching)
(thaw frozen-with-caching)))
(is (= (mapv meta (thaw frozen-with-caching))
[{:id :v1} {:id :v2} {:id :v1} {:id :v2}]))))
;;;; Stable binary representation of vals
(deftest _stable-bin