GitLab

* improve performance of sample_neighbors

* some more improve

* test script

* benchmarks

* multi process

* update more tests

* WIP

* adding two API for state saving

* add create from state

* upd test

* missing file

* wip: pickle/unpickle

* more c apis

* find the problem of empty data array

* add null array; pickling speed is bad

* still bad perf

* still bad perf

* wip

* fix the pickle speed test; now everything looks good

* minor fix

* bugfix

* some lint fix

* address comments

* more fix

* fix lint

* add utest for random.choice

* add utest for dgl.rand_graph

* fix cpp utests

* try fix ci

* fix bug in TF backend

* upd choice docstring

* address comments

* upd

* try fix compile

* add comment