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From Ted Yu <yuzhih...@gmail.com>
Subject Re: hiding default ctor of HTD
Date Sat, 23 Jul 2011 05:48:32 GMT
The scope of changes is bigger than I thought initially.

The introduction of this method:
  public static Writable newInstance(DataInput dataInput)
would probably lead to an abstract class which is called, e.g.
WritableWithoutDefaultCtor.

      if(Writable.class.isAssignableFrom(instanceClass)){

if(WritableWithoutDefaultCtor.class.isAssignableFrom(instanceClass)){

HTD would be the first beneficiary.

On Fri, Jul 22, 2011 at 10:03 PM, Stack <stack@duboce.net> wrote:

> You are fixing it for HTD only?  Not all Writables?
> St>Ack
>
> On Fri, Jul 22, 2011 at 9:50 PM, Ted Yu <yuzhihong@gmail.com> wrote:
> > Looks like I need to enhance the following code in HbaseObjectWritable
> (line
> > 575):
> >        Writable writable = WritableFactories.newInstance(instanceClass,
> > conf);
> >
> > If HTableDescriptor has the following method where T is HTableDescriptor:
> > public <T> T newInstance(DataInput dataInput)
> >
> > HbaseObjectWritable.readObject() would be able to create an HTD instance
> > without relying on its default ctor.
> >
> > On Fri, Jul 22, 2011 at 9:31 PM, Stack <stack@duboce.net> wrote:
> >
> >> Try your proposal.  I don't think it will work.  It'll fail over in
> >> RPC where expectation is that there is a null/default constructor on
> >> every Writable.
> >> St.Ack
> >>
> >> On Fri, Jul 22, 2011 at 9:24 PM, Ted Yu <yuzhihong@gmail.com> wrote:
> >> > My proposal below would make default HTableDescriptor ctor package
> >> private.
> >> >
> >> > If there is no object, I will log a new JIRA.
> >> >
> >> > On Fri, Jul 22, 2011 at 4:27 PM, Ted Yu (JIRA) <jira@apache.org>
> wrote:
> >> >
> >> >>
> >> >>    [
> >> >>
> >>
> https://issues.apache.org/jira/browse/HBASE-4127?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13069840#comment-13069840
> >> ]
> >> >>
> >> >> Ted Yu commented on HBASE-4127:
> >> >> -------------------------------
> >> >>
> >> >> +1 on the patch.
> >> >>
> >> >> Long term, we should hide this ctor, HTableDescriptor().
> >> >> Its existence is to support the following pattern:
> >> >> {code}
> >> >>      hTableDescriptor = new HTableDescriptor();
> >> >>      hTableDescriptor.readFields(fsDataInputStream);
> >> >> {code}
> >> >> I think we should replace this ctor with the following:
> >> >> {code}
> >> >> public HTableDescriptor getTableDescriptor(DataInputStream
> >> dataInputStream)
> >> >> {code}
> >> >>
> >> >> > HBaseAdmin : Don't modify table's name away
> >> >> > -------------------------------------------
> >> >> >
> >> >> >                 Key: HBASE-4127
> >> >> >                 URL:
> https://issues.apache.org/jira/browse/HBASE-4127
> >> >> >             Project: HBase
> >> >> >          Issue Type: Bug
> >> >> >          Components: client, master
> >> >> >    Affects Versions: 0.92.0
> >> >> >            Reporter: Nicolas Spiegelberg
> >> >> >            Assignee: Nicolas Spiegelberg
> >> >> >            Priority: Blocker
> >> >> >         Attachments: HBASE-4127.patch
> >> >> >
> >> >> >
> >> >> > One of the developers was using the default constructor for
> >> >> HTableDescriptor, which is sadly a bad constructor that should never
> be
> >> >> used. It made the tablename empty in META & caused an ERROR cycle
as
> >> region
> >> >> onlining kept failing. We should have never let this happen. Don't
do
> >> table
> >> >> modifications if the HTableDescriptor name doesn't match the table
> name
> >> >> passed in.
> >> >>
> >> >> --
> >> >> This message is automatically generated by JIRA.
> >> >> For more information on JIRA, see:
> >> http://www.atlassian.com/software/jira
> >> >>
> >> >>
> >> >>
> >> >
> >>
> >
>

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