Add a new transaction OP (collection hint) to ObjectStore.
Signed-off-by: Guang Yang (yguang@yahoo-inc.com)
Implement the collection hint transaction, add a new transation type as expected number of objects.
Signed-off-by: Guang Yang (yguang@yahoo-inc.com)
Add tests for collection hint.
Signed-off-by: Guang Yang (yguang@yahoo-inc.com)