[thread-safety] make Pool subclasses return ownership
[thread-safety] make Pool subclasses return ownership

Reviewed By: peterogithub

Differential Revision: D5452925

fbshipit-source-id: f450ce6

ropas/infer,ropas/infer,jvillard/infer,blzq/infer,ropas/infer,facebook/infer,facebook/infer,blzq/infer,jvillard/infer,facebook/infer,facebook/infer,ropas/infer,blzq/infer,jvillard/infer,facebook/infer,blzq/infer,ropas/infer,facebook/infer,jvillard/infer,blzq/infer,ropas/infer,jvillard/infer,blzq/infer,jvillard/infer,jvillard/infer,facebook/infer