On Sun, 18 Aug 2013, Loic Dachary wrote:
> Hi Ceph,
>
> I've implemented a draft of the Erasure Code plugin loader in the context of
> http://tracker.ceph.com/issues/5878. It has a trivial unit test and an
> example plugin. It would be great if someone could do a quick review. The
> general idea is that the erasure code pool calls something like:
>
> ErasureCodePlugin::factory(&erasure_code, "example", parameters)
>
> as shown at
>
> https://github.com/ceph/ceph/blob/5a2b1d66ae17b78addc14fee68c73985412f3c8c/src/test/osd/TestErasureCode.cc#L28
>
> to get an object implementing the interface
>
> https://github.com/ceph/ceph/blob/5a2b1d66ae17b78addc14fee68c73985412f3c8c/src/osd/ErasureCodeInterface.h
>
> which matches the proposal described at
>
> https://github.com/dachary/ceph/blob/wip-4929/doc/dev/osd_internals/erasure-code.rst#erasure-code-library-abstract-api
>
> The draft is at
>
> https://github.com/ceph/ceph/commit/5a2b1d66ae17b78addc14fee68c73985412f3c8c
>
> Thanks in advance :-)
I haven't been following this discussion too closely, but taking a look
now, the first 3 make sense, but
virtual map<int, bufferptr> decode(const set<int> &want_to_read, const
map<int, bufferptr> &chunks) = 0;
it seems like this one should be more like
virtual int decode(const map<int, bufferptr> &chunks, bufferlist *out);
As in, you'd decode the chunks you have to get the actual data. If you
want to get (missing) chunks for recovery, you'd do
minimum_to_decode(...); // see what we need
<fetch those chunks from other nodes>
decode(...); // reconstruct original buffer
encode(...); // encode missing chunks from original data
sage
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