pytorch

c19adfff - [DataLoader] Introduce ConcatMapDataPipe functional datapipe (#61010)

[DataLoader] Introduce ConcatMapDataPipe functional datapipe (#61010) Summary: As part of https://github.com/pytorch/pytorch/issues/57031, this PR adds the ConcatMapDataPipe functional datapipe for the MapDataPipe class. We may need to discuss how to treat the datapipes with no valid length. For now, I just use them as if they have infinite length and the `__getitem__` could not go pass them. Thank you for your time on reviewing this~ cc ejguan Pull Request resolved: https://github.com/pytorch/pytorch/pull/61010 Reviewed By: soulitzer Differential Revision: D29587679 Pulled By: ejguan fbshipit-source-id: 5eb97fa727209bec6c534520057c64a78000626e