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From "Mingliang Liu (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-9027) Refactor o.a.h.hdfs.DataStreamer::isLazyPersist() method
Date Tue, 08 Sep 2015 19:51:45 GMT

     [ https://issues.apache.org/jira/browse/HDFS-9027?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Mingliang Liu updated HDFS-9027:
    Summary: Refactor o.a.h.hdfs.DataStreamer::isLazyPersist() method  (was: Refactor o.a.h.hdfs.DataStreamer$isLazyPersist()

> Refactor o.a.h.hdfs.DataStreamer::isLazyPersist() method
> --------------------------------------------------------
>                 Key: HDFS-9027
>                 URL: https://issues.apache.org/jira/browse/HDFS-9027
>             Project: Hadoop HDFS
>          Issue Type: Task
>            Reporter: Mingliang Liu
>            Assignee: Mingliang Liu
>         Attachments: HDFS-9027.000.patch
> In method {{isLazyPersist()}}, the {{org.apache.hadoop.hdfs.DataStreamer}} class checks
whether the HDFS file is lazy persist. It does two things:
> 1. Create a class-wide _static_ {{BlockStoragePolicySuite}} object, which builds an array
of {{BlockStoragePolicy}} internally
> 2. Get a block storage policy object from the {{blockStoragePolicySuite}} by policy name
> This has two side effects:
> 1. Takes time to iterate the pre-built block storage policy array in order to find the
_same_ policy every time whose id matters only (as we need to compare the file status policy
id with lazy persist policy id)
> 2. {{DataStreamer}} class imports {{BlockStoragePolicySuite}}. The former should be moved
to {{hadoop-hdfs-client}} module, while the latter can stay in {{hadoop-hdfs}} module.
> Actually, we have the block storage policy IDs, which can be used to compare with HDFS
file status' policy id, as following:
> {code}
> static boolean isLazyPersist(HdfsFileStatus stat) {
>     return stat.getStoragePolicy() == HdfsConstants.MEMORY_STORAGE_POLICY_ID;
> }
> {code}
> This way, we only need to move the block storage policies' IDs from {{HdfsServerConstant}}
({{hadoop-hdfs}} module) to {{HdfsConstants}} ({{hadoop-hdfs-client}} module).
> Another reason we should move those block storage policy IDs is that the block storage
policy names were moved to {{HdfsConstants}} already.

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