[jira] [Updated] (SLING-8854) In-file and In-memory queue-providers for Forward Distribution report incorrect value for processing "Attempts"

["Ashish Chopra (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SLING-8854?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ashish Chopra updated SLING-8854:
---------------------------------
    Attachment: 0001-SLING-8854-In-file-and-In-memory-queue-providers-for.patch

> In-file and In-memory queue-providers for Forward Distribution report incorrect value for processing "Attempts"
> ---------------------------------------------------------------------------------------------------------------
>
>                 Key: SLING-8854
>                 URL: https://issues.apache.org/jira/browse/SLING-8854
>             Project: Sling
>          Issue Type: Bug
>          Components: Content Distribution
>    Affects Versions: Content Distribution Core 0.4.0
>            Reporter: Ashish Chopra
>            Priority: Major
>         Attachments: 0001-SLING-8854-In-file-and-In-memory-queue-providers-for.patch
>
>
> {{ForwardDistributionAgentFactory}} allows specifying "In-Memory" and "In-File" queue-providers [0]. Both these implementations are provided by {{SimpleDistributionQueue}} [1].
> While responding to a queue-processing request, the head of the queue is fetched to create a {{DistributionQueueEntry}}, which encapsulates a {{DistributionQueueItemStatus}}. While retrieving the queue-head-entry, the number-of-attempts are also incremented by 1, implying _one more_ processing-attempt to have happened on a given queue-item. [2]
> The trouble arises from the fact that {{SimpleDistributionQueue#getHead}} ends up being called from at least three other places:
> # Queue status Health Check [3], which is a periodic job
> # UI (via {{ExtendedDistributionServiceResourceProvider}}) [4]
> # Distribution Queue status MBean [5]
> Out of these, #1 is most troublesome - because of its periodic nature, the number of Attempts for a queue-item that's being processed (or, is blocked) will keep on increasing without corresponding dequeue-attempts.
> Due to #2, everytime the queue status is delivered to the UI, the attempt would again increase. Similar would be the case of MBean invocations.
> This needs to be addressed. Notably, "Sling Jobs" based queue doesn't suffer from this issue because it relies on retry-counts as maintained by Sling Job Execution Engine.
> [0] https://github.com/apache/sling-org-apache-sling-distribution-core/blob/deb3d2ae33c4f4678c8503091a9fffdbb141e569/src/main/java/org/apache/sling/distribution/agent/impl/ForwardDistributionAgentFactory.java#L258-L262
> [1] https://github.com/apache/sling-org-apache-sling-distribution-core/blob/deb3d2ae33c4f4678c8503091a9fffdbb141e569/src/main/java/org/apache/sling/distribution/queue/impl/simple/SimpleDistributionQueue.java
> [2] https://github.com/apache/sling-org-apache-sling-distribution-core/blob/deb3d2ae33c4f4678c8503091a9fffdbb141e569/src/main/java/org/apache/sling/distribution/queue/impl/simple/SimpleDistributionQueue.java#L110-L112
> [3] https://github.com/apache/sling-org-apache-sling-distribution-core/blob/deb3d2ae33c4f4678c8503091a9fffdbb141e569/src/main/java/org/apache/sling/distribution/monitor/DistributionQueueHealthCheck.java#L113
> [4] https://github.com/apache/sling-org-apache-sling-distribution-core/blob/deb3d2ae33c4f4678c8503091a9fffdbb141e569/src/main/java/org/apache/sling/distribution/resources/impl/ExtendedDistributionServiceResourceProvider.java#L158
> [5] https://github.com/apache/sling-org-apache-sling-distribution-core/blob/deb3d2ae33c4f4678c8503091a9fffdbb141e569/src/main/java/org/apache/sling/distribution/monitor/impl/DistributionQueueMBeanImpl.java#L62-L91



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