test-shared-cache:
  Initial draft for the unit test of "common/shared_cache.hpp".

Signed-off-by: Cheng Cheng <ccheng.leo@gmail.com>
               Loic Dachary <loic@dachary.org>
test-shared-cache:
  Add test for "lower_bound" method.
  Add multithread tests for "lookup" and "lower_bound" methods.

Signed-off-by: Cheng Cheng <ccheng.leo@gmail.com>
               Loic Dachary <loic@dachary.org>
Merge pull request #2597 from cchengleo/wip-test-shared-cache

test shared cache

Reviewed-by: Loic Dachary <loic-201408@dachary.org>