[PATCH] D33977: [libcxx][WIP] Experimental support for a scheduler for use in the parallel stl algorithms

[Erik Pilkington via Phabricator via cfe-commits]

erik.pilkington created this revision.
Herald added a reviewer: EricWF.

This patch adds a simple work-stealing scheduler meant for use as a fallback implementation for the C++17 parallel stl algorithms. This scheme follows a very simple fork/join API that should be easy to map onto different underlying concurrency implementations if they are available. This should be suitable for implementing par & par_unseq on top of.

I also tried this out with a lock-free deque[0]. This provides a modest performance improvement, and might be worth implementing. For the sake of doing this incrementally this patch just contains a locking deque.

Please see the recent thread on cfe-dev for context: http://lists.llvm.org/pipermail/cfe-dev/2017-May/053841.html

I'm still pretty new to libc++ and to parallel stuff, so please feel free to tear this patch apart!
Thanks for taking a look,
Erik

[0]: https://pdfs.semanticscholar.org/3771/77bb82105c35e6e26ebad1698a20688473bd.pdf


https://reviews.llvm.org/D33977

Files:
  include/experimental/execution
  src/experimental/execution.cpp
  test/libcxx/experimental/execution/fork_join.pass.cpp

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