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https://issues.apache.org/jira/browse/HDFS-12203?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16102195#comment-16102195
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Manoj Govindassamy commented on HDFS-12203:
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Adding [~yzhangal], [~jojochuang], [~daryn] for more discussion.
> INodeAttributesProvider#getAttributes() support for default/passthrough mode
> ----------------------------------------------------------------------------
>
> Key: HDFS-12203
> URL: https://issues.apache.org/jira/browse/HDFS-12203
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Manoj Govindassamy
> Assignee: Manoj Govindassamy
>
> {{INodeAttributeProvider}}
> {noformat}
> ..
> public abstract INodeAttributes getAttributes(String[] pathElements,
> INodeAttributes inode);
> public INodeAttributes getAttributes(byte[][] components, INodeAttributes
> inode) {
> String[] elements = new String[components.length];
> for (int i = 0; i < elements.length; i++) {
> elements[i] = DFSUtil.bytes2String(components[i]);
> }
> return getAttributes(elements, inode);
> }
> {noformat}
> The abstract method {{INodeAttributesProvider#getAttributes()}} currently
> takes in INode path elements and the INode. Many a times, the provider falls
> back to the local INode attributes. But, there isn't a way for the caller to
> tell the provider to fall back to local attribute on demand. Below is one
> such usecase, where the caller of getAttributes() wants to use the local
> attributes instead of the one coming from the external provider.
> Assume the external attributes provider takes care of providing custom
> ACLFeature for some specific directories and all its descendants (like
> Sentry) and fallsback to the default INode ACLFeature for all other
> files/directories. And lets assume that the external provider also has its
> meta data properly replicated to another site.
> An operation like snapshot diff iterates over the children of given snapshot
> pair and generates the diff list. In order to generate the diff list, files
> are compared which involves their metadata comparisons. Once HDFS-12201 is
> fixed, metadata comparisons will compare the attributes from external
> providers as well. Given that external attributes can be ignored as they are
> taken care by other means, Snapshot diff wants the meta data comparison to
> ignore the features coming from external attribute provider and fall back to
> the local INode features. This on-demand fall-back or passthrough mode for
> INodeAttributesProvider will help to avoid the huge performance, or memory
> over consumption problems arising out of the external provider plugins.
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