[libcxx-commits] [PATCH] D67086: Implement syncstream (p0053)

Zoe Carver via Phabricator via libcxx-commits libcxx-commits at lists.llvm.org
Wed Sep 11 09:21:38 PDT 2019

zoecarver marked an inline comment as done.
zoecarver added inline comments.

Comment at: libcxx/include/syncstream:208
+template <class _CharT, class _Traits, class _Allocator>
+    typename basic_syncbuf<_CharT, _Traits, _Allocator>::streambuf_type*,
mclow.lists wrote:
> Why `unordered_map` as opposed to `map`? Does `std::hash< streambuf_type*>` have some behavior that you want?  [ Note: `unordered_map` might be the right choice. But you should say //why// it is the right choice somewhere. ]
The pointer specialization of `std::hash` should help with memory usage. Unordered map has a find complexity of O(1) which is the real reason I think it should be used. This stream should be CPU performant above all else, with hundreds of threads trying to access an element, I think the benefit of find speed outweighs the slight increase in memory consumption. Do you agree?

  rG LLVM Github Monorepo



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