indexing working with mapdb
cache size locally
append a random UUID to map name

avoid collision with dimension name
Merge branch 'offheap-incremental-index' into mapdb-branch
TimeAndDims optimise to store indexes
Merge branch 'offheap-incremental-index' into mapdb-branch
use putIfAbsent instead of get and put

use putIfAbsent instead of get and put. reduce no. of calls to mapdb
decreases latency.
use hash map and in memory sort during index generation

use hash map and in memory sort during index generation
add custom serializer

add custom serializers
Merge branch 'offheap-incremental-index' into mapdb-branch
make OffheapIncrementalIndex tuneable
Merge branch 'offheap-incremental-index' into mapdb-branch
review comments + mapdb deadlock fix
make ingestOffheap tuneable
fix merge conflicts
separate offheapIncrementalIndex implementation
license header
Merge pull request #752 from metamx/mapdb-branch

Offheap dimensions