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From "Chris Nauroth (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-12635) Adding Append API support for WASB
Date Mon, 11 Jan 2016 22:47:40 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-12635?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15092854#comment-15092854
] 

Chris Nauroth commented on HADOOP-12635:
----------------------------------------

[~dchickabasapa], thank you for incorporating the feedback.

I'm finding it challenging to follow the logic of whether or not the test-and-set succeeds
based on the {{updatePossible}} flag.  Instead of tracking it in a flag, I'm wondering if
the whole logic could be simplified to the following, which wouldn't require a flag tracked
in another variable.  Let me know your thoughts.

{code}
        // If there is prior lease metadata, and that least timeout has not yet expired, then
testCondition must match lease condition.
        if (metadata.containsKey(APPEND_LEASE) &&
            currentTime - Long.parseLong(metadata.get(APPEND_LEASE_LAST_MODIFIED)) <= BlockBlobAppendStream.APPEND_LEASE_TIMEOUT
&&
            !metadata.get(APPEND_LEASE).equals(Boolean.toString(testCondition))) {
          return false;
        }
        // Do metadata update here.
        return true;
{code}

I am assuming that {{uploadMetadata}} is atomic, so that we will never have a case where metadata
exists containing {{append_lease}}, but not {{append_lease_last_modified}}.  If that operation
is not in fact atomic, please let me know.

After addressing that, please feel free to click the Submit Patch button for a pre-commit
run.

> Adding Append API support for WASB
> ----------------------------------
>
>                 Key: HADOOP-12635
>                 URL: https://issues.apache.org/jira/browse/HADOOP-12635
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: azure
>    Affects Versions: 2.7.1
>            Reporter: Dushyanth
>            Assignee: Dushyanth
>         Attachments: Append API.docx, HADOOP-12635.001.patch, HADOOP-12635.002.patch
>
>
> Currently the WASB implementation of the HDFS interface does not support Append API.
This JIRA is added to design and implement the Append API support to WASB. The intended support
for Append would only support a single writer.  



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