Initial commit for dataset op python

Added signature to barrier

Adde compiling barrier code

Rebasing, fixed new compile errors

Final fix for make_unique

Added pybind API for barrier

Fixed pyfunc invocation

python interface - sync_wait

!1 sync_wait python interface
* python interface - sync_wait

fix test

update test

update test

Added new test case

add test case

test for shuffle + batch

Added two-sync test case

Restrited that no shuffle after sync

Added sync to pipeline info

block first databuffer as well

Intelligently get batch size

Fix default case

Lock Pair shares among all iterators

Added fix for empty character

Fixed up test case formatting

Fix end of epoch in sync_wait

Fixing CI

Merge pull request !377 from h.farahat/end_iterator

Merge pull request !183 from JunhanHu/cpp_sampler

Signed-off-by: leonwanghui <leon.wanghui@huawei.com>