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https://issues.apache.org/jira/browse/HDFS-12977?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16372125#comment-16372125
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Plamen Jeliazkov commented on HDFS-12977:
-----------------------------------------
Attached new patch.
I created two new interfaces in order to keep common and hdfs as separate
modules:
TransactionIdProvider and TransactionIdObserver – names are subject to change
per review of course, but their names should suggest their function. The gist
is that the FSNamesystem implements the TransactionIdProvider and the DFSClient
implements the TransactionIdObserver. With some additional changes to RpcEngine
I was able to make it so that via Server constructor I can pass a
TransactionIdProvider and via Client I can pass a TransactionIdObserver.
This makes it so we do not need to add a ton of try/finally across
NameNodeRpcServer.
I am not really happy with the code in Client currently; if anyone can provide
some guidance on how I can better pass an object into its constructor I would
greatly appreciate it.
Regarding (1) I was also able to pass in HdfsServerConstants.INVALID_TXID by
delegating it to the TransactionIdProvider via a method
"getInvalidTransactionId" that is used to initialize the RpcResponse
transactionId until it gets a valid txid.
> Add stateId to RPC headers.
> ---------------------------
>
> Key: HDFS-12977
> URL: https://issues.apache.org/jira/browse/HDFS-12977
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ipc, namenode
> Reporter: Konstantin Shvachko
> Assignee: Plamen Jeliazkov
> Priority: Major
> Attachments: HDFS_12977.trunk.001.patch, HDFS_12977.trunk.002.patch
>
>
> stateId is a new field in the RPC headers of NameNode proto calls.
> stateId is the journal transaction Id, which represents LastSeenId for the
> clients and LastWrittenId for NameNodes. See more in [reads from Standby
> design
> doc|https://issues.apache.org/jira/secure/attachment/12902925/ConsistentReadsFromStandbyNode.pdf].
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