The wakePend flag currently has undefined behavior as multiple threads
read and write to it without a consistent locking mechanism. This
switches writes and reads to use C++11's release-consume ordering
when available. Without this patch, we have undefined behavior - which
is illegal with C++11.

The release-consume ordering is sufficient to guarantee atomicity
and the ordering of wakePend writes; other than that, it's a very
weak memory model. In practice, this is a guarantee already provided
by all interesting architectures (it only generates different assembler
on DEC Alpha).

Fixes #167

You can merge this Pull Request by running

  git pull https://github.com/bbockelm/xrootd fix-wakepend-loads

Or view, comment on, or merge it at:

  https://github.com/xrootd/xrootd/pull/170

Commit Summary

File Changes

Patch Links:

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