[
https://issues.apache.org/jira/browse/ZOOKEEPER-1001?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13009233#comment-13009233
]
dhruba borthakur commented on ZOOKEEPER-1001:
---------------------------------------------
Thanks for the picture, Flavio. I like Option 2. The folowing two comments are
for Option 2:
1. It would be nice to have the two parameters that Option 2 uses (the time or
size after which ZK is updated) be configurable.
2. The diagram shows that the App1 periodically informs ZK about the last
committed seqid. Can this interaction be handled by the BK client itself
(instead of the App). For example,BookKeeper.java can have the following API:
{quote}
public long createLedger(...., boolean updateZk)
{quite}
If updateZk is true, then the BookKeeper client itself will udpate zk with the
last committed transaction at some given periodicity. This is similar in some
sense to filesystems where the file-metadata becomes globally visible/readable
after some time (even though the writer is continuing to write to the file).
> Read from open ledger
> ---------------------
>
> Key: ZOOKEEPER-1001
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1001
> Project: ZooKeeper
> Issue Type: New Feature
> Components: contrib-bookkeeper
> Reporter: Flavio Junqueira
> Attachments: zk-1001-design-doc.pdf, zk-1001-design-doc.pdf
>
>
> The BookKeeper client currently does not allow a client to read from an open
> ledger. That is, if the creator of a ledger is still writing to it (and the
> ledger is not closed), then an attempt to open the same ledger for reading
> will execute the code to recover the ledger, assuming that the ledger has not
> been correctly closed.
> It seems that there are applications that do require the ability to read from
> a ledger while it is being written to, and the main goal of this jira is to
> discuss possible implementations of this feature.
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
