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[CLJ-1408] Add transient keyword to cached toString() value in _str Created: 19/Apr/14  Updated: 07/Oct/14  Resolved: 07/Oct/14

Status: Closed
Project: Clojure
Component/s: None
Affects Version/s: Release 1.6
Fix Version/s: Release 1.7

Type: Defect Priority: Minor
Reporter: Tomasz Nurkiewicz Assignee: Unassigned
Resolution: Completed Votes: 0
Labels: interop

Attachments: Text File CLJ-1408-2.patch     Text File CLJ-1408-3.patch     Text File CLJ-1408.patch    
Patch: Code and Test
Approval: Ok


_str field in Keyword and Symbol classes lazily caches result of toString(). Because this field is not transient, serializing (using Java serialization) any keyword or symbol before and after calling toString() for the first time yields different results:

(import (java.io ByteArrayOutputStream ObjectOutputStream
                 ByteArrayInputStream  ObjectInputStream))

(defn- serialize [obj]
  (with-open [bos (ByteArrayOutputStream.)
              stream (ObjectOutputStream. bos)]
    (.writeObject stream obj)
    (-> bos .toByteArray seq)))

;; keyword example

(def k1 (serialize :k))
(println :k)
(def k2 (serialize :k))

(= k1 k2) ;;=> false 

;; symbol example

(def sym 'a)

(def s1 (serialize sym))
(println sym)
(def s2 (serialize sym))

(= s1 s2) ;;=> false

This issue came up when I was trying to use keywords as key in [Hazelcast](https://github.com/hazelcast/hazelcast) map. Hazelcast uses serialized keys in various scenarios, thus if I first put something to map under key :k and then print :k, I can no longer find such key.

Approach: Add transient keyword to _str field in Keyword and Symbol classes

Patch: CLJ-1408-3.patch

Screened by: Brenton Ashworth

Comment by Alex Miller [ 19/Apr/14 7:28 AM ]

Hi Tomasz, it would be good to fix this, can you sign the CLA?

Comment by Tomasz Nurkiewicz [ 20/Apr/14 7:26 AM ]

Thanks, I'll sign and send CLA ASAP.

Comment by Tomasz Nurkiewicz [ 08/May/14 4:10 PM ]

My contributor greement arrived, please merge this patch whenever you find suitable.

Comment by Alex Miller [ 08/May/14 10:16 PM ]

Hi Tomasz, I noticed you added the private keyword - please remove that and update the patch.

Comment by Tomasz Nurkiewicz [ 09/May/14 3:55 PM ]

Removed `private` keyword

Comment by Alex Miller [ 20/Jun/14 9:22 AM ]

On second thought, it looks like we have most of the infrastructure for serialization testing anyways, so would appreciate an updated patch with the example turned into a serialization test. Please see test/clojure/test_clojure/serialization.clj for a place to put this (using existing roundtrip function).

Comment by Andy Fingerhut [ 01/Aug/14 9:29 PM ]

Tomasz, in addition to Alex's previous comment, it appears that a commit made to Clojure master earlier today causes your patches to no longer apply cleanly. I haven't looked to see whether updating the patches would be easy, but likely it is.

Comment by Alex Miller [ 22/Aug/14 11:00 PM ]

Updated the patch for latest master and added the obvious test.

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