Marc M. Adkins wrote:
This definitely looks better based on the part I have reviewed. It doesn't appear to me that the old code will ever allow multiple readers.I've re-coded the Windows rwlock based on the OS/2 algorithm implemented by Brian Havard. My test program doesn't show starvation with this algorithm. I'm assuming that the code is stable and works correctly on OS/2, and it's essentially the same code here, plus it passes all the tests I know how to do so I'm submitting the code for review.
Somewhat to my surprise the performance test program that comes with APR seems to show an increase in speed of 30% - 50%. Possibly because the old code had two mutex waits for a read lock and the new code has one.
I was initially surprised because the new code has tests on return values and an extra level of subroutine calling not present in the old code. Not to mention additional functionality: tryrdlock and trywrlock are both working now and starvation should be prevented. When does more functionality ever mean faster?
I'm attaching the two changed files, which were essentially rewritten. So far as I can tell, the 2.1 code is still the same in CVS, so just replacing the files in their entirety should be sufficient. I can do diffs if that is better. I don't personally have CVS write access.
mma
+1 with some coding style cleanups (which I'll do if I commit this code tomorrow).
Bill
