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From "Nanda kumar (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDDS-271) Create a block iterator to iterate blocks in a container
Date Thu, 26 Jul 2018 13:49:00 GMT

    [ https://issues.apache.org/jira/browse/HDDS-271?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16558327#comment-16558327

Nanda kumar commented on HDDS-271:

As this is an iterator we can throw NoSuchElementException if the iteration has no more element
instead of returning null.

If {{hasNext}} returns true we should be able to return the next block on {{nextBlock}} call.
Consider a case where we have two blocks [key1:block1, #deleting#key2:block2]. For the first
{{hasNext}} call we will return {{true}} and the {{nextBlock}} call will return key1:block1.
For the second {{hasNext}} call we will return {{true}} but the {{nextBlock}} call will return
{{null}}. This will create inconsistent behavior in code wherever the iterator is used. We
cannot fully rely on {{hasNext}} call anymore.

> Create a block iterator to iterate blocks in a container
> --------------------------------------------------------
>                 Key: HDDS-271
>                 URL: https://issues.apache.org/jira/browse/HDDS-271
>             Project: Hadoop Distributed Data Store
>          Issue Type: Improvement
>            Reporter: Bharat Viswanadham
>            Assignee: Bharat Viswanadham
>            Priority: Major
>             Fix For: 0.2.1
>         Attachments: HDDS-271.00.patch, HDDS-271.01.patch, HDDS-271.02.patch, HDDS-271.03.patch
> Create a block iterator to scan all blocks in a container.
> This one will be useful during implementation of container scanner.

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