5 Jul
2004
5 Jul
'04
9:43 p.m.
Howard Hinnant wrote:
I'm not following that x==y always holds. If two threads concurrently hold a read lock, and concurrently try to obtain a write lock, only one thread will get the write lock, the other will block. Assuming the one thread that got the write lock changes x, then the thread that blocked will fire its assert when it finally unblocks and gets the write lock.
What am I missing?
As I understand it, if two threads hold a read lock, no thread can obtain a write lock. Write lock == exclusive access. This corresponds to the POSIX memory model where write accesses must be exclusive, but read accesses can be shared with other read accesses. But I may be wrong. ;-)