Mailing-List: contact hdfs-issues-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
Date: Thu, 9 Mar 2017 02:01:38 +0000 (UTC)
From: "SammiChen (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.12934082.1453805032000.18093.1489024898180@Atlassian.JIRA>
In-Reply-To: <JIRA.12934082.1453805032000@Atlassian.JIRA>
References: <JIRA.12934082.1453805032000@Atlassian.JIRA> <JIRA.12934082.1453805032731@jira-lw-us.apache.org>
Subject: [jira] [Updated] (HDFS-9705) Refine the behaviour of
 getFileChecksum when length = 0
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
archived-at: Thu, 09 Mar 2017 02:01:42 -0000


     [ https://issues.apache.org/jira/browse/HDFS-9705?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

SammiChen updated HDFS-9705:
----------------------------
    Attachment:     (was: HDFS-9705-v7.patch)

> Refine the behaviour of getFileChecksum when length = 0
> -------------------------------------------------------
>
>                 Key: HDFS-9705
>                 URL: https://issues.apache.org/jira/browse/HDFS-9705
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>            Reporter: Kai Zheng
>            Assignee: Kai Zheng
>            Priority: Minor
>         Attachments: HDFS-9705-v1.patch, HDFS-9705-v2.patch, HDFS-9705-v3.patch, HDFS-9705-v4.patch, HDFS-9705-v5.patch, HDFS-9705-v6.patch, HDFS-9705-v7.patch
>
>
> {{FileSystem#getFileChecksum}} may accept {{length}} parameter and 0 is a valid value. Currently it will return {{null}} when length is 0, in the following code block:
> {code}
>     //compute file MD5
>     final MD5Hash fileMD5 = MD5Hash.digest(md5out.getData());
>     switch (crcType) {
>     case CRC32:
>       return new MD5MD5CRC32GzipFileChecksum(bytesPerCRC,
>           crcPerBlock, fileMD5);
>     case CRC32C:
>       return new MD5MD5CRC32CastagnoliFileChecksum(bytesPerCRC,
>           crcPerBlock, fileMD5);
>     default:
>       // If there is no block allocated for the file,
>       // return one with the magic entry that matches what previous
>       // hdfs versions return.
>       if (locatedblocks.size() == 0) {
>         return new MD5MD5CRC32GzipFileChecksum(0, 0, fileMD5);
>       }
>       // we should never get here since the validity was checked
>       // when getCrcType() was called above.
>       return null;
>     }
> {code}
> The comment says "we should never get here since the validity was checked" but it does. As we're using the MD5-MD5-X approach, and {{EMPTY--CONTENT}} actually is a valid case in which the MD5 value is {{d41d8cd98f00b204e9800998ecf8427e}}, so suggest we return a reasonable value other than null. At least some useful information in the returned value can be seen, like values from block checksum header.


--
This message was sent by Atlassian JIRA
(v6.3.15#6346)

---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-issues-unsubscribe@hadoop.apache.org
For additional commands, e-mail: hdfs-issues-help@hadoop.apache.org