On Tue, Apr 16, 2013 at 9:44 PM, Jeff King [off-list ref] wrote:

On Tue, Apr 16, 2013 at 04:13:56PM +0200, Johannes Sixt wrote:

quoted

quoted

I'm not clear on what you are suggesting. That we protect only the main
thread from recursion, or that we drop the check entirely? Or that we
implement thread-local storage for this case without using pthread_once?

Anything(*) that does not require pthread_once. A pthread_once
implementation on Windows would be tricky and voluminous and and on top of
it very likely to be done differently for gcc and MSVC. I don't like to go
there if we can avoid it.

This seems to have been settled as a "we don't need to go there"
already, but just in case; here's an implementation of
PTHREAD_MUTEX_INITIALIZER using double-checked locks, and it would
probably be repurposable to do pthread_once if needed:

https://github.com/kusma/git/commit/c2d7190ed64652c3ac8ea1f2800ff8e7d0b6c01e

Yes, it's not pretty, it's error-prone; the best thing would be not to do it.