[infinispan-dev] Multi get API

[William Burns]

I am nearing completion of the new multi get command [1], allowing for
more efficient retrieval of multiple keys at the same time.  Thanks
again to Radim for a lot of the initial work.

In doing so though I want to make sure I get feedback on how we want
the API to actually look, since this is much more difficult to change
down the line.

There are a few things in particular I wanted to discuss.

1. The actual name of the method.  The main suggestions I have seen
are getAll or getMany.  I do like the naming of the former, however it
seems a bit misleading (remember API is getAll(Set) since we are
really getting a subset.  So I am thinking the possibilities at this
point are getAllOf, getAllFor or getMany.  I am leaning maybe towards
the last one (getMany).  I am open to any suggestions though.

2. What should the return value be for this method.  Currently this
returns a Map<K, V> which makes sense when we retain these values in
the local transactional context and is pretty nice and clean for end
users.

The other idea is to use a streaming API possibly returning an
Iterable<CacheEntry<K, V>>.  The streaming return value doesn't seem
as intuitive to me, but opens us up for more efficient usage
especially when there may be a lot of keys passed in (also results can
be processed concurrently while retrieval is still occurring).

I would lean towards returning the Map<K, V> value, however the next
point could change that.

3. Where this method should live.  Right now this method is on the
BasicCache interface which is a parent of both Cache (embedded) and
RemoteCache (remote).  Unfortunately for remote clients to be as
efficient as possible we really need a Streaming API so that we don't
have multiple copies of data in memory at multiple places at the same
time.  For that reason I suggest we use the streaminig API for both or
have a different API for remote vs embedded.

Let me know what you guys think.

Cheers,

 - Will

[1] https://issues.jboss.org/browse/ISPN-2183