Package org.alfresco.repo.thumbnail.conditions

Class NodeEligibleForRethumbnailingEvaluator

  • All Implemented Interfaces:
    ActionConditionEvaluator, org.springframework.beans.factory.Aware, org.springframework.beans.factory.BeanNameAware
    public class NodeEligibleForRethumbnailingEvaluator
extends ActionConditionEvaluatorAbstractBase
    This action evaluator is specifically created for the Thumbnail Service. It is used to evaluate whether a ThumbnailDefinition should be executed - based on previous failed thumbnail attempts for that definition on that source node, as well as some configuration data.

    The behaviour is as follows:

    • All content nodes are eligible for thumbnailing initially. Of course thumbnails can only ever be attempted for those content mime types that have at least one registered and active ContentTransformer.
    • If the first attempt to produce a thumbnail for a node fails, then it may be retried up to a maximum of system.thumbnail.retryCount times.
    • These initial retries to produce a thumbnail will occur not more often than every system.thumbnail.retryPeriod seconds and will use which ever content transformers the content service gives.
    • If a thumbnail is not successfully produced for a node after these attempts then it is considered to be a 'difficult' piece of content with respect to thumbnailing and the assumption is that a thumbnail may never be available for it. However, in order to allow for the possibility of software upgrades or similiar, which may make the content thumbnailable at a later date, further attempts will be made, but at a much reduced frequency.
    • Difficult pieces of content will not be attempted more often than every system.thumbnail.quietPeriod seconds.
    • The attempts to thumbnail difficult pieces of content can be disabled by setting system.thumbnail.quietPeriodRetriesEnabled to false.
    At all times, thumbnails will be attempted when a user navigates to a page which needs to show the relevant thumbnail (lazy production).
    Since:
    3.5.0
    Author:
    Neil Mc Erlean.