[jira] Commented: (JCR-2874) Locked helper class improvements

["Jukka Zitting (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JCR-2874?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12994809#comment-12994809 ] 

Jukka Zitting commented on JCR-2874:
------------------------------------

Good stuff, thanks! I committed the patch in revision 1070916.

3. Agreed, throwing an exception in the timeout case seems like a more natural solution than returning a special sentinel value. Ideally the exception would be a subclass of RepositoryException to make it easier to capture.

4. We have a bit of a problem with unit testing in jcr-commons, as due to the way dependencies are ordered we can't rely on jackrabbit-core to provide a JCR repository against which to test the jcr-commons functionality. Thus we'd either need to put such jcr-commons integration tests somewhat counterintuitively in jackrabbit-core or set up a complicated mock repository for use within jcr-commons.

PS. Note that we try to use only spaces for indentation. Your patch had some tabs in it that I cleaned away before committing.

> Locked helper class improvements
> --------------------------------
>
>                 Key: JCR-2874
>                 URL: https://issues.apache.org/jira/browse/JCR-2874
>             Project: Jackrabbit Content Repository
>          Issue Type: Improvement
>          Components: jackrabbit-jcr-commons, jackrabbit-spi-commons
>            Reporter: Alex Parvulescu
>            Priority: Minor
>         Attachments: lock_upgrade.diff
>
>
> Currently there are 2 helper classes called Locked, that serve the same purpose:
> one in jcr-commons http://jackrabbit.apache.org/api/2.2/org/apache/jackrabbit/util/Locked.html
> and the other one in spi-commons http://jackrabbit.apache.org/api/2.2/org/apache/jackrabbit/spi/commons/lock/Locked.html
> There was a discussion a while back about deprecating one of them. the issue affected JR 1.4 and it is now closed. I guess the old patches have not been applied: https://issues.apache.org/jira/browse/JCR-1169
> Anyway, I propose to keep the one in jcr-commons and deprecate the other one.
> Also, while we are on the matter, I'd like to propose some improvements to this class:
> 1. make the lock configurable, basically add a flag to say if it is session scoped or not (currently it is hard coded as a session wide lock).
> 2. upgrade the lock code to use the LockManager (http://www.day.com/maven/javax.jcr/javadocs/jcr-2.0/javax/jcr/lock/LockManager.html) - this means that the class will rely only on the JCR 2.0. this is a potentially breaking change, although a lot of the classes in this module depend directly on the 2.0 API
> 3. allow the Locked class to use generics. The biggest issue here is the timeout behavior: on timeout you get the TIMED_OUT token object, and you have to compare the response to that, to make sure that the code ran properly. I think the simplest solution would be to not touch the class directly and build a wrapper class that is generified, and throws a RepositoryException in case of a timeout.
> This would turn this code( from the javadoc)
>   Node counter = ...;
>   Object ret = new Locked() {
>      protected Object run(Node counter) throws RepositoryException {
>          ...
>      }
>   }.with(counter, false);
>   if (ret == Locked.TIMED_OUT) {
>      // do whatever you think is appropriate in this case
>   } else {
>      // get the value
>      long nextValue = ((Long) ret).longValue();
>   }
> into 
>   Node counter = ...;
>   Long ret = new LockedWrapper<Long>() {
>      protected Object run(Node counter) throws RepositoryException {
>          ...
>      }
>   }.with(counter, false);
>   // handle the timeout as a RepositoryException
> 4. lock tests location? (this is more of an observation than an actual issue it came to me via 'find . -name *Lock*Test.java')
> There are some lock tests in jackrabbit-core: 
>  - jackrabbit-core/src/test/java/org/apache/jackrabbit/core/LockTest.java
>  - jackrabbit-core/src/test/java/org/apache/jackrabbit/core/lock/LockTimeoutTest.java
>  - jackrabbit-core/src/test/java/org/apache/jackrabbit/core/lock/ConcurrentLockingWithTransactionsTest.java
>  - jackrabbit-core/src/test/java/org/apache/jackrabbit/core/lock/ExtendedLockingTest.java
>  - jackrabbit-core/src/test/java/org/apache/jackrabbit/core/lock/ConcurrentLockingTest.java
> ...some in jackrabbit-jcr2spi:
>  - jackrabbit-jcr2spi/src/test/java/org/apache/jackrabbit/jcr2spi/lock/OpenScopedLockTest.java
>  - jackrabbit-jcr2spi/src/test/java/org/apache/jackrabbit/jcr2spi/lock/SessionScopedLockTest.java
>  - jackrabbit-jcr2spi/src/test/java/org/apache/jackrabbit/jcr2spi/lock/DeepLockTest.java
>  - jackrabbit-jcr2spi/src/test/java/org/apache/jackrabbit/jcr2spi/lock/AbstractLockTest.java
> and others in jackrabbit-jcr-tests:
>  - jackrabbit-jcr-tests/src/main/java/org/apache/jackrabbit/test/api/observation/LockingTest.java
>  - jackrabbit-jcr-tests/src/main/java/org/apache/jackrabbit/test/api/lock/SetValueLockExceptionTest.java
>  - jackrabbit-jcr-tests/src/main/java/org/apache/jackrabbit/test/api/lock/LockManagerTest.java
>  - jackrabbit-jcr-tests/src/main/java/org/apache/jackrabbit/test/api/lock/OpenScopedLockTest.java
>  - jackrabbit-jcr-tests/src/main/java/org/apache/jackrabbit/test/api/lock/LockTest.java
>  - jackrabbit-jcr-tests/src/main/java/org/apache/jackrabbit/test/api/lock/SessionScopedLockTest.java
>  - jackrabbit-jcr-tests/src/main/java/org/apache/jackrabbit/test/api/lock/DeepLockTest.java
>  - jackrabbit-jcr-tests/src/main/java/org/apache/jackrabbit/test/api/lock/AbstractLockTest.java
> I'd like to move this one: org.apache.jackrabbit.core.LockTest from the jackrabbit-core to the jackrabbit-jcr-commons where the implementation class lives.
> I'll add a patch for 1 & 2, but the rest I need your opinion.

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