Hi,
Something that explains this could be useful in the interprocess documentation.
I don't mention anywhere that upgradable lock is recursive, so this is not going to work if you use it that way.
The difference with interprocess_mutex not being recursive and upgradable_mutex not being recursive is that if you try to lock interprocess_mutex recursively you will get a deadlock *every time*, whereas locking the upgradable_mutex recursively (lock_shareable) will work *most* of the time. This is the reason I think that this might be worth a mention in the docs. It took me a fair while to work out that this was what caused me some rare deadlocks, and having a mention in the docs may help others.
I really would like to implement option 1 or 2, but I still don't see an easy solution. Sorry!
Yes, that was what I was afraid of. I had a look at the code, but didn't really have time/patience to delve deeply into it. I was hoping that there was some easy way of doing this that was beyond my understanding of the implementation. I thought of changing the internal mutex into a recursive_mutex, but I couldn't easily work out what would happen if I did that... Anyway, if there is no easy way to "fix" this, I will stick with making sure that I don't lock recursively... Which is obviously the correct solution with the current behaviour. Lars