[infinispan-issues] [JBoss JIRA] Commented: (ISPN-1345) Dirty reads may occurs on mutable objects

[Manik Surtani (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-1345?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12623961#comment-12623961 ] 

Manik Surtani commented on ISPN-1345:
-------------------------------------

Yes, I am working on a similar scheme, to be compliant with some recent developments in JSR 107.  As you say, it will involve:

* No copying for known immutable types
* No copying for POJOs annotated with @Immutable
* Otherwise, copy on write.  (Not on read).

But this is work in progress.

> Dirty reads may occurs on mutable objects
> -----------------------------------------
>
>                 Key: ISPN-1345
>                 URL: https://issues.jboss.org/browse/ISPN-1345
>             Project: Infinispan
>          Issue Type: Bug
>          Components: Transactions
>    Affects Versions: 5.0.0.FINAL
>         Environment: Windows Java 1.6.0_26
>            Reporter: Christophe Labouisse
>            Assignee: Manik Surtani
>             Fix For: 5.1.0.ALPHA1, 5.1.0.FINAL
>
>
> In local mode, I create a cache like this:
> {code}
> cacheManager = new DefaultCacheManager();
> cacheManager.getDefaultConfiguration().fluent().storeAsBinary().transaction().cacheStopTimeout(5000);
> final Configuration config = new Configuration().fluent().transactionManagerLookup(this.tmLookup).locking()
>                 .isolationLevel(IsolationLevel.READ_COMMITED).build();
> this.cacheManager.defineConfiguration("Gruik", config);
> this.cache = this.cacheManager.getCache("Gruik");
> {code}
> When retrieving data using {{cache.get(_key_)}} I find out that Infinispan returns the object instance actually stored in the cache datastore. This is OK when the inserted objects are immutable but fails to achieve isolation when using mutable objects.
> For instance on a simple Pojo with a {{get/setValue}}.
> ||Step||Reader||Writer||
> |1|Starts transaction| |
> |2|{{value = cache.get(KEY);}}| |
> |3|{{System.out.println(value.getValue());}} Prints 42| |
> |4| |Starts transaction|
> |5| |{{value = cache.get(KEY);}} Same instance than step 2|
> |6| |{{value.setValue(666); // Prepare update}}|
> |7|{{System.out.println(value.getValue());}} Prints 666 !| |
> |8|{{value = cache.get(KEY);}} Same instance than step 2| |
> |9| |{{cache.put(KEY,value);}}|
> |10| |Commits transaction|
> |11|{{value = cache.get(KEY);}} Same instance than step 2| |
> |12|{{System.out.println(value.getValue());}} Prints 666| |
> |13|Commits transaction| |
> According to the READ_COMMITTED specification, the value printed on step 7 should be 42 as the change to 666 is not committed yet.

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